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17 pages, 3237 KiB

Open AccessArticle

Acrylated Chitosan Nanoparticles with Enhanced Mucoadhesion

by Shaked Eliyahu¹, Anat Aharon^2,3 and Havazelet Bianco-Peled^1,4,*

¹ The Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel

² Bruce Rappaport Faculty of Medicine, Technion—Israel Institute of Technology, Haifa 3200003, Israel

³ Department of Hematology and Bone Marrow Transplantation, Rambam Health Care Campus, Haifa 3109601, Israel

⁴ Department of Chemical Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel

Polymers 2018, 10(2), 106; https://doi.org/10.3390/polym10020106 - 23 Jan 2018

Cited by 29 | Viewed by 6638

Abstract

The aim of this study was to investigate the effect of acrylate modification on the mucoadhesion of chitosan at the nanoscale. Nanoparticles were fabricated from acrylated chitosan (ACS) via ionic gelation with tripolyphosphate and were characterized in terms of size, zeta potential, stability, [...] Read more.

The aim of this study was to investigate the effect of acrylate modification on the mucoadhesion of chitosan at the nanoscale. Nanoparticles were fabricated from acrylated chitosan (ACS) via ionic gelation with tripolyphosphate and were characterized in terms of size, zeta potential, stability, and nanoparticle yield. Chitosan (CS) nanoparticles, serving as a control, were fabricated using the same procedure. The mucoadhesion of the nanoparticles was evaluated using the flow-through method after different incubation periods. The retention percentages of ACS nanoparticles were found to be significantly higher than those of CS nanoparticles, for all studied time intervals. An additional indication for the increased mucoadhesion of ACS nanoparticles was the increase in particle size obtained from the mucin particle method, in which mucin and nanoparticles are mixed at different ratios. NMR data verified the presence of free acrylate groups on the ACS nanoparticles. Thus, the improved mucoadhesion could be due to a Michael-type addition reaction between the nanoparticles and thiol groups present in mucin glycoprotein, in addition to entanglements and hydrogen bonding. Overall, ACS nanoparticles exhibit enhanced mucoadhesion properties as compared to CS nanoparticles and could be used as vehicles for drug delivery systems. Full article

(This article belongs to the Special Issue Advances in Mucoadhesive Polymers and Formulations for Transmucosal Drug Delivery)

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24 pages, 8798 KiB

Open AccessArticle

Demonstrating the Influence of Physical Aging on the Functional Properties of Shape-Memory Polymers

by Ehsan Ghobadi^1,*

, Mohamed Elsayed^2,3, Reinhard Krause-Rehberg² and Holger Steeb^1,4

¹ Institute of Mechanics (CE), University of Stuttgart, 70565 Stuttgart, Germany

² Faculty of Natural Sciences II-Chemistry, Physics and Mathematics, Martin-Luther-University Halle, 06120 Halle, Germany

³ Department of Physics, Faculty of Science, Minia University, 61519 Minia, Egypt

⁴ SimTech, University of Stuttgart, 70565 Stuttgart, Germany

Polymers 2018, 10(2), 107; https://doi.org/10.3390/polym10020107 - 23 Jan 2018

Cited by 5 | Viewed by 5574

Abstract

Polymers that allow the adjustment of Shape-Memory properties by the variation of physical parameters during programming are advantageous compared with their counterparts requiring synthesis of new material. Here, we explored the influence of hydrolytic (physical) aging on the Shape-Memory properties of the polyetherurethane [...] Read more.

Polymers that allow the adjustment of Shape-Memory properties by the variation of physical parameters during programming are advantageous compared with their counterparts requiring synthesis of new material. Here, we explored the influence of hydrolytic (physical) aging on the Shape-Memory properties of the polyetherurethane system Estane, programmed in repeated thermomechanical cycles under torsional load. We were able to demonstrate that physical aging occurred through water adsorption influencing the existing free volume of the samples as well as the functional properties of Estane. Dynamic Mechanical Thermal Analysis determined the glass transition temperatures of dry and hydrolytically aged samples. According to our results, Estane takes up to 3 wt % water for two weeks (at an ambient temperature of θ = 20 °C). The glass transition temperatures of dry samples decreased within this period from 55 to 48 °C as a consequence of a plasticization effect. Next, for both samples, six subsequent thermomechanical cycles under torsional loading conditions were performed. We were able to confirm that hydrolytically aged samples showed higher shape recovery ratios of R_r ≥ 97%, although dry samples revealed better shape fixity values of about 98%. Moreover, it was observed that the shape fixity ratio of both dry and hydrolytically (physically) aged samples remained almost unchanged even after six successive cycles. Besides this, the shape recovery ratio values of the aged samples were nearly unaltered, although the shape recovery values of the dry samples increased from R_r = 81% in the first cycle to 96% at the end of six repeated cycles. Further, the evolution of the free volume as a function of temperature was studied using Positron Annihilation Lifetime Spectroscopy. It was shown that the uptake of two other organic solvents (acetone and ethanol) resulted in much higher specific free volume inside the samples and, consequently, a softening effect was observed. We anticipate that the presented approach will assist in defining design criteria for self-sufficiently moving scaffolds within a knowledge-based development process. Full article

(This article belongs to the Special Issue Shape Memory Polymers)

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13 pages, 3230 KiB

Open AccessArticle

Electrosprayed Core–Shell Composite Microbeads Based on Pectin-Arabinoxylans for Insulin Carrying: Aggregation and Size Dispersion Control

by Agustín Rascón-Chu^1,*

, Jonathan A. Díaz-Baca¹, Elizabeth Carvajal-Millan¹

, Elías Pérez-López²

, Arland T. Hotchkiss³, Humberto González-Ríos¹

, Rene Balandrán-Quintana¹ and Alma C. Campa-Mada¹

¹ Research Center for Food and Development, CIAD, A.C., Carretera a La Victoria Km. 0.6, Hermosillo, Sonora 83304, Mexico

² Institute of Physics, Autonomous University of San Luis Potosí, Álvaro Obregón #64, San Luis Potosí SLP 78000, Mexico

³ Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndoor, PA 19038, USA

Polymers 2018, 10(2), 108; https://doi.org/10.3390/polym10020108 - 23 Jan 2018

Cited by 22 | Viewed by 6103

Abstract

Aggregation and coalescence are major drawbacks that contribute to polydispersity in microparticles and nanoparticles fabricated from diverse biopolymers. This study presents the evaluation of a novel method for the direct, electrospray-induced fabrication of small, CaCl₂/ethanol-hardened low methoxy pectin/arabinoxylans composite microbeads. The [...] Read more.

Aggregation and coalescence are major drawbacks that contribute to polydispersity in microparticles and nanoparticles fabricated from diverse biopolymers. This study presents the evaluation of a novel method for the direct, electrospray-induced fabrication of small, CaCl₂/ethanol-hardened low methoxy pectin/arabinoxylans composite microbeads. The electrospray method was evaluated to control particle size by adjusting voltage, flux, and crosslinking solution content of CaCl₂/ethanol. A bead diameter of 1µm was set as reference to test the capability of this method. Insulin was chosen as a model carried molecule. Statistical analysis was a central composite rotatable design (CCRD) with a factorial arrangement of 2⁴. The variables studied were magnitude and particle size dispersion. For the determination of these variables, light diffraction techniques, scanning electron microscopy, transmission electron microscopy, and confocal laser scanning microscopy were used. Major interaction was found for ethanol and CaCl₂ as well as flow and voltage. Stable spherical structures of core–shell beads were obtained with neither aggregation nor coalescence for all treatments where ethanol was included in the crosslinking solution, and the average diameter within 1 ± 0.024 μm for 11 KV, 75% ethanol with 11% CaCl₂, and flow of 0.97 mL/h. Full article

(This article belongs to the Special Issue Core-Shell Structured Polymers)

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12 pages, 7065 KiB

Open AccessArticle

Collagen-Coated Poly(lactide-co-glycolide)/Hydroxyapatite Scaffold Incorporated with DGEA Peptide for Synergistic Repair of Skull Defect

by Ming Bi¹, Hui Han², Shujun Dong³, Ying Zhang^4,*, Weiguo Xu⁵, Bitao Zhu⁵, Jingyun Wang¹, Yanmin Zhou^1,* and Jianxun Ding^5,*

¹ Department of General Dentistry, School and Hospital of Stomatology, Jilin University, Changchun 130021, China

² Department of Thyroid Surgery, The First Hospital of Jilin University, Changchun 130021, China

³ VIP Integrated Department, School and Hospital of Stomatology, Jilin University, Changchun 130021, China

⁴ Department of Orthopedics, Zhongshan Hospital Affiliated to Xiamen University, Xiamin 361004, China

⁵ Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China

Polymers 2018, 10(2), 109; https://doi.org/10.3390/polym10020109 - 24 Jan 2018

Cited by 26 | Viewed by 5840

Abstract

The treatment of large-area bone defects remains a challenge; however, various strategies have been developed to improve the performances of scaffolds in bone tissue engineering. In this study, poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) scaffold was coated with Asp-Gly-Glu-Ala (DGEA)-incorporated collagen for the repair of [...] Read more.

The treatment of large-area bone defects remains a challenge; however, various strategies have been developed to improve the performances of scaffolds in bone tissue engineering. In this study, poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) scaffold was coated with Asp-Gly-Glu-Ala (DGEA)-incorporated collagen for the repair of rat skull defect. Our results indicated that the mechanical strength and hydrophilicity of the PLGA/HA scaffold were clearly improved and conducive to cell adhesion and proliferation. The collagen-coated scaffold with DGEA significantly promoted the repair of skull defect. These findings indicated that a combination of collagen coating and DGEA improved scaffold properties for bone regeneration, thereby providing a new potential strategy for scaffold design. Full article

(This article belongs to the Special Issue Polymer Scaffolds for Biomedical Application)

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13 pages, 3173 KiB

Open AccessArticle

Epitaxial Crystallization Behavior of Poly(butylene adipate) on Orientated Poly(butylene succinate) Substrate

by Haijun Wang^1,2,*, Zhijin Gao^1,2, Xi Yang¹, Kun Liu¹, Min Zhang³, Xihuai Qiang¹ and Xuechuan Wang¹

¹ College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China

² National Demonstration Center for Experimental Light Chemistry Engineering Education, Shaanxi University of Science and Technology, Xi’an 710021, China

³ School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China

Polymers 2018, 10(2), 110; https://doi.org/10.3390/polym10020110 - 24 Jan 2018

Cited by 16 | Viewed by 6005

Abstract

The crystallization behavior of poly(butylene adipate) (PBA) in the sheared PBS/PBA blend, as well as on highly orientated poly(butylene succinate) (PBS) substrate, was studied by means of DSC, POM, Raman microscopy, and XRD. The results showed that the pre-existing orientated PBS crystals exhibit [...] Read more.

The crystallization behavior of poly(butylene adipate) (PBA) in the sheared PBS/PBA blend, as well as on highly orientated poly(butylene succinate) (PBS) substrate, was studied by means of DSC, POM, Raman microscopy, and XRD. The results showed that the pre-existing orientated PBS crystals exhibit a very strong nucleation ability toward PBA as reflected by the increased crystallization temperature and the occurrence of heteroepitaxy and transcrystallization of PBA on the PBS substrate. The epitaxial crystallization of PBA on the PBS substrate results in the formation of α-form PBA crystals in any crystallization conditions. Full article

(This article belongs to the Special Issue Biodegradable and Biobased Polyesters)

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12 pages, 4483 KiB

Open AccessArticle

Enhanced Solubilization of Fluoranthene by Hydroxypropyl β-Cyclodextrin Oligomer for Bioremediation

by Kyeong Hui Park¹, Jae Min Choi²

, Eunae Cho² and Seunho Jung^2,*

¹ Department of Systems Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Center for Biotechnology Research in UBITA (CBRU), Konkuk University, Seoul 05029, Korea

² Center for Biotechnology Research in UBITA (CBRU), Institute for Ubiquitous Information Technology and Applications (UBITA), Konkuk University, Seoul 05029, Korea

Polymers 2018, 10(2), 111; https://doi.org/10.3390/polym10020111 - 24 Jan 2018

Cited by 10 | Viewed by 6166

Abstract

Fluoranthene (FT) is a polycyclic aromatic hydrocarbon (PAH), consisting of naphthalene and benzene rings connected by a five-member ring. It is widespread in the environment. The hydrophobicity of FT limits its availability for biological uptake and degradation. In this study, hydroxypropyl β-cyclodextrin oligomers [...] Read more.

Fluoranthene (FT) is a polycyclic aromatic hydrocarbon (PAH), consisting of naphthalene and benzene rings connected by a five-member ring. It is widespread in the environment. The hydrophobicity of FT limits its availability for biological uptake and degradation. In this study, hydroxypropyl β-cyclodextrin oligomers (HP-β-CD-ol) were synthesized with epichlorohydrin (EP), while the solubility enhancement of FT by HP-β-CD-ol was investigated in water. The synthesized HP-β-CD-ol was characterized by MALDI-TOF mass spectrometry (MS), ¹H NMR, and ¹³C NMR spectroscopy. The solubility of FT increased 178-fold due to the complex formation with HP-β-CD oligomers. The inclusion complexes of FT/HP-β-CD-ol were analyzed using Fourier-Transform Infrared (FT-IR), Differential Scanning Calorimetry (DSC), Scanning Electron Microscope (SEM), and Nuclear Overhauser Effect Spectroscopy Nuclear magnetic resonance (NOESY NMR) spectroscopy. On the basis of these results, HP-β-CD-ol is recommended as a potential solubilizer for the development of PAH removal systems. Full article

(This article belongs to the Special Issue Polysaccharides)

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13 pages, 7181 KiB

Open AccessArticle

Novel Biological Hydrogel: Swelling Behaviors Study in Salt Solutions with Different Ionic Valence Number

by Yu Wang^1,*

, Guidong He², Zheng Li^2,3,*

, Jiachuan Hua², Maoqi Wu², Jixian Gong², Jianfei Zhang², Li-tong Ban¹ and Liang Huang¹

¹ College of Agronomy and Resources Environment, Tianjin Agricultural University, Tianjin 300384, China

² Key Laboratory of Advanced Textile Composites (Tianjin Polytechnic University), Ministry of Education; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China

³ Key Laboratory of Science & Technology of Eco-Textile, Donghua University, Shanghai 201620, China

Polymers 2018, 10(2), 112; https://doi.org/10.3390/polym10020112 - 24 Jan 2018

Cited by 28 | Viewed by 6352

Abstract

In this paper, poly γ-glutamic acid/ε-polylysine (γ-PGA/ε-PL) hydrogels were successful prepared. The γ-PGA/ε-PL hydrogels could be used to remove Na⁺, Ca²⁺, and Cr³⁺ from aqueous solution and were characterized by scanning electron microscopy. The performance of hydrogels were [...] Read more.

In this paper, poly γ-glutamic acid/ε-polylysine (γ-PGA/ε-PL) hydrogels were successful prepared. The γ-PGA/ε-PL hydrogels could be used to remove Na⁺, Ca²⁺, and Cr³⁺ from aqueous solution and were characterized by scanning electron microscopy. The performance of hydrogels were estimated under different ionic concentration, temperature, and pH. The results showed that the ionic concentration and the pH significantly influenced the swelling capacity of γ-PGA/ε-PL hydrogels. The swelling capacities of γ-PGA/ε-PL hydrogels were decreased with the increase of the ionic concentration. However, the swelling capacity of the γ-PGA/ε-PL hydrogel was increased with the increase of the pH. The swelling kinetics indicated that γ-PGA/ε-PL hydrogels presented a more limited swelling degree in metal ion solutions with higher ionic valence numbers than in ion solutions with lower ionic valence numbers. However, the swelling kinetics of γ-PGA/ε-PL hydrogels showed that they proposed a satisfactory description in NaCl and CaCl₂ solutions. The adsorption process was fitted with a pseudo-second-order rate equation model. Moreover, the desorption kinetics of γ-PGA/ε-PL hydrogels showed that they could release most of the adsorption ions. Considering the biocompatibility, biodegradability, and ionic-sensitive properties, we propose that these γ-PGA/ε-PL hydrogels have high potential to be used in environmental protection, medical treatment, and other related fields. Full article

(This article belongs to the Special Issue Hydrogels in Tissue Engineering and Regenerative Medicine)

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11 pages, 1666 KiB

Open AccessArticle

Adsorption of Anionic Polyacrylamide onto Coal and Kaolinite Calculated from the Extended DLVO Theory Using the van Oss-Chaudhury-Good Theory

by Wenjie Zou^1,2,*

, Jinglin Zhao¹ and Chunbao Sun¹

¹ Civil and Resource Engineering School, University of Science and Technology Beijing, Beijing 100083, China

² Key Laboratory of Coal Processing and Efficient Utilization, Ministry of Education, Xuzhou 221116, China

Polymers 2018, 10(2), 113; https://doi.org/10.3390/polym10020113 - 25 Jan 2018

Cited by 34 | Viewed by 4916

Abstract

The dispersion behavior of particles is of great significance in selective flocculation flotation. The interfacial interaction between coal and the main impurity mineral (kaolinite) particles with the effect of an anionic polyacrylamide (PAM A401) was explored by the extended Derjagin–Landau–Verwey–Overbeek (DLVO) theory. The [...] Read more.

The dispersion behavior of particles is of great significance in selective flocculation flotation. The interfacial interaction between coal and the main impurity mineral (kaolinite) particles with the effect of an anionic polyacrylamide (PAM A401) was explored by the extended Derjagin–Landau–Verwey–Overbeek (DLVO) theory. The involved surface free energy components of fine mineral particles were estimated using the van Oss-Chaudhury-Good theory and Washburn equation. After adsorption of PAM A401, the range and absolute value of the hydrophobic interaction V_HA of the coal particles decreased, the electrostatic repulsive potential increased, and the total potential energy changed from −1.66 × 10⁵ to −4.03 × 10⁴ kT at the separation distance of 5 nm. For interactions between the kaolinite and coal particles after PAM A401 adsorption, the electrostatic repulsive potential increased and the hydrophilic repulsive potential energy decreased. The energy barrier at the separation distance of 0.2 nm decreased from 2.78 × 10⁴ to 2.29 × 10⁴ kT. The total potential energy between the kaolinite and coal particles after PAM A401 adsorption was still repulsive, and the range of the repulsive interaction increased from ~0.05 to 47 nm to ~0.05 to 50 nm. The total potential energy of the coal particles after PAM A401 adsorption was still attractive. This behavior of coal and kaolinite particles with the effect of PAM A401 indicates the possibility of enhanced fine coal separation by the method of selective flocculation flotation. Full article

(This article belongs to the Special Issue Polymer-Clay (Nano)Composites)

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16 pages, 5617 KiB

Open AccessArticle

Shape Memory Behavior of PET Foams

by Loredana Santo^*

, Denise Bellisario

and Fabrizio Quadrini

Department of Industrial Engineering, University of Rome “Tor Vergata”, Via del Politecnico 1, 00133 Rome, Italy

Polymers 2018, 10(2), 115; https://doi.org/10.3390/polym10020115 - 25 Jan 2018

Cited by 19 | Viewed by 6819

Abstract

Shape memory properties of PET (polyethylene-terephthalate) foams have been evaluated for two different foam densities. Samples were subjected to multiple memory-recovery cycles along three different directions to measure the effect of foam anisotropy on static mechanical and shape memory properties. The memory cycle [...] Read more.

Shape memory properties of PET (polyethylene-terephthalate) foams have been evaluated for two different foam densities. Samples were subjected to multiple memory-recovery cycles along three different directions to measure the effect of foam anisotropy on static mechanical and shape memory properties. The memory cycle was performed by uniaxial compression tests at room temperature. Despite these severe conditions, PET foams demonstrated very good shape memory behavior with shape recovery always higher than 90%. Due to cycling, the mechanical performance of foam samples is partially reduced, mainly along the extrusion direction of the foam panels. Despite this loss of static performance, shape memory properties are only partially affected by thermo-mechanical cycles. The maximum reduction is 10% for shape fixity and 3% for shape recovery. The experimental results are particularly interesting considering that compression tests were undertaken at room temperature. Indeed, PET foams seem to be optimal candidates for self-repairing structures. Full article

(This article belongs to the Special Issue Shape Memory Polymers)

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13 pages, 3373 KiB

Open AccessArticle

A New Route for Preparation of Hydrophobic Silica Nanoparticles Using a Mixture of Poly(dimethylsiloxane) and Diethyl Carbonate

by Iryna Protsak^1,2,3, Evgeniy Pakhlov², Valentyn Tertykh², Zi-Chun Le^1,* and Wen Dong³

¹ College of Science, Zhejiang University of Technology, Hangzhou 310023, China

² Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine, 03164 Kyiv, Ukraine

³ College of Environment, Zhejiang University of Technology, Hangzhou 310023, China

Polymers 2018, 10(2), 116; https://doi.org/10.3390/polym10020116 - 26 Jan 2018

Cited by 29 | Viewed by 10375

Abstract

Organosilicon layers chemically anchored on silica surfaces show high carbon content, good thermal and chemical stability and find numerous applications as fillers in polymer systems, thickeners in dispersing media, and as the stationary phases and carriers in chromatography. Methyl-terminated poly(dimethylsiloxanes) (PDMSs) are typically [...] Read more.

Organosilicon layers chemically anchored on silica surfaces show high carbon content, good thermal and chemical stability and find numerous applications as fillers in polymer systems, thickeners in dispersing media, and as the stationary phases and carriers in chromatography. Methyl-terminated poly(dimethylsiloxanes) (PDMSs) are typically considered to be inert and not suitable for surface modification because of the absence of readily hydrolyzable groups. Therefore, in this paper, we report a new approach for surface modification of silica (SiO₂) nanoparticles with poly(dimethylsiloxanes) with different lengths of polymer chains (PDMS-20, PDMS-50, PDMS-100) in the presence of diethyl carbonate (DEC) as initiator of siloxane bond splitting. Infrared spectroscopy (IR), elemental analysis (CHN), transmission electron microscopy (TEM), atomic force microscopy (AFM), rotational viscosity and contact angle of wetting were employed for the characterization of the raw fumed silica and modified silica nanoparticles. Elemental analysis data revealed that the carbon content in the grafted layer is higher than 8 wt % for all modified silicas, but it decreases significantly after sample treatment in polar media for silicas which were modified using neat PDMS. The IR spectroscopy data indicated full involvement of free silanol groups in the chemisorption process at a relatively low temperature (220 °C) for all resulting samples. The contact angle studies confirmed hydrophobic surface properties of the obtained materials. The rheology results illustrated that fumed silica modified with mixtures of PDMS-x/DEC exhibited thixotropic behavior in industrial oil (I-40A), and exhibited a fully reversible nanostructure and shorter structure recovery time than nanosilicas modified with neat PDMS. The obtained results from AFM and TEM analysis revealed that the modification of fumed silica with mixtures of PDMS-20/DEC allows obtaining narrow particle size distribution with uniform dispersity and an average particle size of 15–17 nm. The fumed silica nanoparticles chemically modified with mixtures of PDMS-x/DEC have potential applications such as nanofillers of various polymeric systems, thickeners in dispersing media, and additives in coatings. Full article

(This article belongs to the Special Issue Siloxane-Based Polymers)

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23 pages, 3017 KiB

Open AccessArticle

Structural, Mechanical, and Transport Properties of Electron Beam-Irradiated Chitosan Membranes at Different Doses

by Alia Baroudi¹, Carmen García-Payo¹

and Mohamed Khayet^1,2,*

¹ Department of Applied Physics I, Faculty of Physics, University Complutense of Madrid, Avda. Complutense, s/n, 28040 Madrid, Spain

² Madrid Institute for Advanced Studies of Water (IMDEA Water Institute), Avda. Punto Com n° 2, Alcalá de Henares, 28805 Madrid, Spain

Polymers 2018, 10(2), 117; https://doi.org/10.3390/polym10020117 - 26 Jan 2018

Cited by 32 | Viewed by 4730

Abstract

Chitosan powder irradiated by electron beam at different doses, up to 250 kGy, was used to prepare membranes for drug release applications. The irradiation effect on the molecular weight of powder chitosan, the characteristics of the prepared membranes, and their transport of sulfamerazine [...] Read more.

Chitosan powder irradiated by electron beam at different doses, up to 250 kGy, was used to prepare membranes for drug release applications. The irradiation effect on the molecular weight of powder chitosan, the characteristics of the prepared membranes, and their transport of sulfamerazine sodium salt (SULF) were investigated. The effect of the addition of glutaraldehyde (GLA) as a crosslinking agent in the chitosan solution used for the preparation of the membranes was also studied. A decrease in the chitosan molecular weight with the increase in the irradiation dose was observed, while the membranes prepared with the irradiated chitosan at higher dose exhibited lower swelling. However, an opposite behavior was detected when the membranes were prepared with GLA-crosslinked chitosan. A GLA crosslinking agent reduced the crystallinity of the chitosan membranes and the swelling, whereas the water contact angle and SULF transport increased with the increase in the irradiation dose. Full article

(This article belongs to the Collection Polysaccharides)

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11 pages, 4993 KiB

Open AccessArticle

Studies of Interfacial Interaction between Polymer Components on Helical Nanofiber Formation via Co-Electrospinning

by Huihui Wu^1,*

, Shihang Zhao², Wenhua Ding³ and Lei Han²

¹ Pan Tianshou Arts and Design Academy, Ningbo University, Ningbo 315211, China

² School of Materials Science & Chemical Engineering, Ningbo University, Ningbo 315211, China

³ Wu Han Aplus Technology Co., Ltd., Wuhan 430000, China

Polymers 2018, 10(2), 119; https://doi.org/10.3390/polym10020119 - 26 Jan 2018

Cited by 11 | Viewed by 5437

Abstract

Helical fibers in nanoscale have been of increasing interest due to their unique characteristics. To explore the effect of polymer type on helical fiber formation, three polymer systems, Poly(m-phenylene isophthalamide) (Nomex)/polyurethane (TPU), polystyrene (PS)/TPU and polyacrylonitril (PAN)/TPU are used to fabricate [...] Read more.

Helical fibers in nanoscale have been of increasing interest due to their unique characteristics. To explore the effect of polymer type on helical fiber formation, three polymer systems, Poly(m-phenylene isophthalamide) (Nomex)/polyurethane (TPU), polystyrene (PS)/TPU and polyacrylonitril (PAN)/TPU are used to fabricate helical nanofibers via co-electrospinning. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and Zeta potential were employed to investigate the interfacial interaction between the two phases of the polymer system. The larger rigidity differential of Nomex and TPU leads to a larger interfacial interaction. The hydrogen bonds help to increase the interfacial interaction between Nomex and TPU components. The attractive force between the chloride-ions contained in Nomex molecules and the free charges on the solution surface lead to a longitudinal interfacial interaction in the Nomex/TPU system. The analysis results provide the explanation of the experimental results that the Nomex/TPU system has the greatest potential for producing helical nanofibers, while the PS/TPU and PAN/TPU systems cannot fabricate helical fibers effectively. This study based on the interfacial interaction between polymer components provides an insight into the mechanism of helical fiber formation. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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12 pages, 7304 KiB

Open AccessArticle

Nucleation Enhancement in Stereodefective Poly(l-lactide) by Free Volume Expansion Resulting from Low-Temperature Pressure CO₂ Preconditioning

by Qiaofeng Lan^1,*

, Jian Yu^2,*, Jun Zhang² and Jiasong He²

¹ School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China

² Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China

Polymers 2018, 10(2), 120; https://doi.org/10.3390/polym10020120 - 26 Jan 2018

Cited by 3 | Viewed by 4471

Abstract

Nucleation enhancement in a highly stereodefective poly(l-lactide) (PLLA) with an optical purity of 88% by low-temperature pressure (0 and 35 °C under 2 MPa) CO₂ preconditioning was investigated using differential scanning calorimetry (DSC), infrared (IR) spectroscopy, polarized optical microscopy (POM) [...] Read more.

Nucleation enhancement in a highly stereodefective poly(l-lactide) (PLLA) with an optical purity of 88% by low-temperature pressure (0 and 35 °C under 2 MPa) CO₂ preconditioning was investigated using differential scanning calorimetry (DSC), infrared (IR) spectroscopy, polarized optical microscopy (POM) as well as positron annihilation lifetime spectroscopy (PALS). Despite the preconditioning of the melt-quenched films for 2 h, IR results indicated that no trace of mesophase was generated and the samples remained in the glassy state. However, judging from the results of DSC, IR, and POM, when compared to the untreated sample, both the treated ones showed a significantly enhanced crystal nucleation effect, resulting in the corresponding greatly enhanced crystallization kinetics. Moreover, owing to the existence of the retrograde vitrification, the conditions of the previous low-pressure CO₂ conditioning affected the nucleation enhancement effect. When compared to the case of 35 °C, the much lower temperature of 0 °C was more effective for nucleation enhancement. The PALS results indicated that the enlarged free volume, which resulted from the CO₂ conditioning, largely accounted for the formation of locally ordered structures, providing many more potential nucleation sites for forming critical nuclei and thus the resulting enhanced crystallization kinetics in glassy PLLA. The present results have implications in understanding the nucleation enhancement effect, in particular in stereodefective PLLA systems, which possess extremely low crystallization ability and are thus probably too problematic to be evaluated by conventional methods. Full article

(This article belongs to the Special Issue Phase Behavior in Polymers)

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10 pages, 3060 KiB

Open AccessArticle

Improving Photovoltaic Properties of P3HT:IC₆₀BA through the Incorporation of Small Molecules

by Binrui Xu^1,†

, Gopalan Sai-Anand^2,3,†

, Anantha-Iyengar Gopalan⁴

, Qiquan Qiao⁵ and Shin-Won Kang^1,*

¹ School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Korea

² Global Innovative Center for Advanced Nanomaterials, Faculty of Engineering and Built Environment, University of Newcastle, Callaghan, NSW 2298, Australia

³ Future Industries Institute, Division of Information Technology, Engineering and Environment, University of South Australia, Mawson Lakes, SA 5095, Australia

⁴ Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu 41566, Korea

⁵ Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University, Brookings, SD 570007, USA

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 121; https://doi.org/10.3390/polym10020121 - 26 Jan 2018

Cited by 24 | Viewed by 8231

Abstract

We investigated the role of a functional solid additive, 2,3-dihydroxypyridine (DHP), in influencing the optoelectronic, morphological, structural and photovoltaic properties of bulk-heterojunction-based polymer solar cells (BHJ PSCs) fabricated using poly(3-hexylthiophene): indene-C₆₀ bisadduct (P3HT:IC₆₀BA) photoactive medium. A dramatic increase in the [...] Read more.

We investigated the role of a functional solid additive, 2,3-dihydroxypyridine (DHP), in influencing the optoelectronic, morphological, structural and photovoltaic properties of bulk-heterojunction-based polymer solar cells (BHJ PSCs) fabricated using poly(3-hexylthiophene): indene-C₆₀ bisadduct (P3HT:IC₆₀BA) photoactive medium. A dramatic increase in the power conversion efficiency (~20%) was witnessed for the BHJ PSCs treated with DHP compared to the pristine devices. A plausible explanation describing the alignment of pyridine moieties of DHP with the indene side groups of IC₆₀BA is presented with a view to improving the performance of the BHJ PSCs via improved crystalline order and hydrophobicity changes. Full article

(This article belongs to the Special Issue Polymers for Energy Applications)

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13 pages, 3896 KiB

Open AccessArticle

The Dispersion of Pulp-Fiber in High-Density Polyethylene via Different Fabrication Processes

by Xiaohui Yang¹

, Guangzhao Wang¹, Menghe Miao²

, Jinquan Yue¹

, Jianxiu Hao¹ and Weihong Wang^1,*

¹ Key Lab of Bio-based Material Science Technology of Education Ministry, Northeast Forestry University, Harbin 150040, China

² CSIRO Manufacturing, 75 Pigdons Road, Waurn Ponds, VIC 3216, Australia

Polymers 2018, 10(2), 122; https://doi.org/10.3390/polym10020122 - 26 Jan 2018

Cited by 12 | Viewed by 5953

Abstract

In this study, a pulp beating machine was used to premix the pulp fibers with high density polyethylene (HDPE) particles in water. The wet or pre-dried pulp fiber/HDPE mixture was then melt-compounded by a twin screw extruder. For further improving the dispersion of [...] Read more.

In this study, a pulp beating machine was used to premix the pulp fibers with high density polyethylene (HDPE) particles in water. The wet or pre-dried pulp fiber/HDPE mixture was then melt-compounded by a twin screw extruder. For further improving the dispersion of pulp fiber, some mixture was forced to pass through the twin-screw extruder twice. The resulting mixture was compression molded to the composite. The fiber distribution was observed by the aid of an optic and scanning electron microscope. The mechanical and rheological properties and creep resistance of the composites were characterized. Test results demonstrate that when the wet pulp fiber/HDPE mixture was subjected to pre-pressing and oven drying prior to extrusion compounding, the resulting composites exhibited homogeneous fiber distribution, superior flexural property, creep-resistance, and high storage modulus. Particularly, its flexural strength and modulus were 57% and 222% higher, respectively, than that of the neat HDPE, while the composites prepared without pre-dried were 19% and 100% higher, respectively. Drying the wet mixture in advance is more effective than re-passing through the extruder for improving the fiber dispersion and composite performance. Full article

(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)

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17 pages, 4124 KiB

Open AccessArticle

Ionic Liquid-Based Thermoplastic Solid Electrolytes Processed by Solvent-Free Procedures

by Francisco González, Víctor Gregorio, Aitor Rubio, Leoncio Garrido

, Nuria García^*

and Pilar Tiemblo^*

Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain

Polymers 2018, 10(2), 124; https://doi.org/10.3390/polym10020124 - 26 Jan 2018

Cited by 21 | Viewed by 5614

Abstract

A series of thermoplastic polymer electrolytes have been prepared employing poly(ethylene oxide) (PEO) as a polymer matrix, bis(trifluoromethane sulfonimide) (LiTFSI), and different room-temperature ionic liquids (RTIL) with bis(fluorosulfonyl)imide (FSI) or TFSI anions. This formulation makes them safe and non-flammable. The electrolytes have been [...] Read more.

A series of thermoplastic polymer electrolytes have been prepared employing poly(ethylene oxide) (PEO) as a polymer matrix, bis(trifluoromethane sulfonimide) (LiTFSI), and different room-temperature ionic liquids (RTIL) with bis(fluorosulfonyl)imide (FSI) or TFSI anions. This formulation makes them safe and non-flammable. The electrolytes have been processed in the absence of solvents by melt compounding at 120 °C, using sepiolite modified with d-α-tocoferol-polyethyleneglycol 1000 succinate (TPGS-S) as a physical cross-linker of PEO. Several concentrations of RTILs, lithium salt, and TPGS-S have been tested in order to obtain the highest ionic conductivity (σ) without losing electrolytes’ mechanical stability. The materials’ rheology and ionic conductivity have been extensively characterized. The excellent crosslinking ability of TPGS-S makes the electrolytes behave as thermoplastic materials, even those with the highest liquid concentration. The electrolytes with the highest concentrations of FSI anion present a σ over 10⁻³ S·cm⁻¹ at 25 °C and close to 10⁻² S·cm⁻¹ at 70 °C, and notably behave as solids at temperatures up to 90 °C despite over 65 wt % of their formulation being liquid. The electrolytes thus obtained are safe solid thermoplastics prepared by industrially scalable procedures and are suitable for energy storage devices, proving the adequacy of polymer-based materials as solid electrolytes for batteries or supercapacitors. Full article

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11 pages, 2568 KiB

Open AccessArticle

Effect of Curing Rate on the Microstructure and Macroscopic Properties of Epoxy Fiberglass Composites

by Ammar Patel¹, Oleksandr Kravchenko² and Ica Manas-Zloczower^1,*

¹ Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA

² Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA 23529, USA

Polymers 2018, 10(2), 125; https://doi.org/10.3390/polym10020125 - 27 Jan 2018

Cited by 32 | Viewed by 7492

Abstract

Curing rates of an epoxy amine system were varied via different curing cycles, and glass-fiber epoxy composites were prepared using the same protocol, with the aim of investigating the correlation between microstructure and composite properties. It was found that the fast curing cycle [...] Read more.

Curing rates of an epoxy amine system were varied via different curing cycles, and glass-fiber epoxy composites were prepared using the same protocol, with the aim of investigating the correlation between microstructure and composite properties. It was found that the fast curing cycle resulted in a non-homogenous network, with a larger percentage of a softer phase. Homogenized composite properties, namely storage modulus and quasi-static intra-laminar shear strength, remained unaffected by the change in resin microstructure. However, fatigue tests revealed a significant reduction in fatigue life for composites cured at fast curing rates, while composites with curing cycles that allowed a pre-cure until the critical gel point, were unaffected by the rate of reaction. This result was explained by the increased role of epoxy microstructure on damage initiation and propagation in the matrix during fatigue life. Therefore, local non-homogeneities in the epoxy matrix, corresponding to regions with variable crosslink density, can play a significant role in limiting the fatigue life of composites and must be considered in the manufacturing of large scale components, where temperature gradients and significant exotherms are expected. Full article

(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)

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11 pages, 1940 KiB

Open AccessArticle

Preparation, Characterization, and Performance Evaluation of Polysulfone Hollow Fiber Membrane with PEBAX or PDMS Coating for Oxygen Enhancement Process

by Kok Chung Chong^1,*

, Soon Onn Lai¹, Woei Jye Lau^2,*

, Hui San Thiam¹, Ahmad Fauzi Ismail² and Rosyiela Azwa Roslan²

¹ Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Kajang 43300, Malaysia

² Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia

Polymers 2018, 10(2), 126; https://doi.org/10.3390/polym10020126 - 28 Jan 2018

Cited by 44 | Viewed by 7188

Abstract

Air pollution is a widely discussed topic amongst the academic and industrial spheres as it can bring adverse effects to human health and economic loss. As humans spend most of their time at the office and at home, good indoor air quality with [...] Read more.

Air pollution is a widely discussed topic amongst the academic and industrial spheres as it can bring adverse effects to human health and economic loss. As humans spend most of their time at the office and at home, good indoor air quality with enriched oxygen concentration is particularly important. In this study, polysulfone (PSF) hollow fiber membranes fabricated by dry-jet wet phase inversion method were coated by a layer of polydimethylsiloxane (PDMS) or poly(ether block amide) (PEBAX) at different concentrations and used to evaluate their performance in gas separation for oxygen enrichment. The surface-coated membranes were characterized using SEM and EDX to determine the coating layer thickness and surface chemical properties, respectively. Results from the gas permeation study revealed that the PSF membrane coated with PDMS offered higher permeance and selectivity compared to the membrane coated with PEBAX. The best performing PDMS-coated membrane demonstrated oxygen and nitrogen gas permeance of 18.31 and 4.01 GPU, respectively with oxygen/nitrogen selectivity of 4.56. Meanwhile, the PEBAX-coated membrane only showed 12.23 and 3.11 GPU for oxygen and nitrogen gas, respectively with a selectivity of 3.94. It can be concluded the PDMS coating is more promising for PSF hollow fiber membrane compared to the PEBAX coating for the oxygen enrichment process. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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13 pages, 5080 KiB

Open AccessArticle

Inverted Organic Solar Cells with Low-Temperature Al-Doped-ZnO Electron Transport Layer Processed from Aqueous Solution

by Qianni Zhang^1,2, Ruizhi Peng^1,2, Chunfu Zhang^1,2,*

, Dazheng Chen^1,*, Zhenhua Lin¹, Jingjing Chang^1,2, Jincheng Zhang^1,2 and Yue Hao¹

¹ Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of Microelectronics, Xidian University, Xi’an 710071, China

² Shaanxi Joint Key Laboratory of Graphene, Xidian University, Xi’an 710071, China

Polymers 2018, 10(2), 127; https://doi.org/10.3390/polym10020127 - 28 Jan 2018

Cited by 26 | Viewed by 8631

Abstract

The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL) at a low temperature in inverted organic solar cells (OSCs). However, to dope the ZnO film processed from the Zn-ammine complex solutions is [...] Read more.

The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL) at a low temperature in inverted organic solar cells (OSCs). However, to dope the ZnO film processed from the Zn-ammine complex solutions is difficult since the introduction of metal ions into the Zn-ammine complex is a nontrivial process as ammonium hydroxide tends to precipitate metal salts due to acid-base neutralization reactions. In this paper, we investigate the inverted OSCs with Al-doped-ZnO ETL made by immersion of metallic Al into the Zn-ammine precursor solution. The effects of ZnO layer with different immersion time of Al on film properties and solar cell performance have been studied. The results show that, with the Al-doped-ZnO ETL, an improvement of the device performance could be obtained compared with the device with the un-doped ZnO ETL. The improved device performance is attributed to the enhancement of charge carrier mobility leading to a decreased charge carrier recombination and improved charge collection efficiency. The fabricated thin film transistors with the same ZnO or AZO films confirm the improved electrical characteristics of the Al doped ZnO film. Full article

(This article belongs to the Special Issue Polymer Solar Cells)

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16 pages, 11297 KiB

Open AccessArticle

Influence of Ethylene Glycol Methacrylate to the Hydration and Transition Behaviors of Thermo-Responsive Interpenetrating Polymeric Network Hydrogels

by Bing Li^1,2

, Qi Zhong^1,2, Dapeng Li³, Ke Xu^1,2, Lu Zhang^1,2 and Jiping Wang^1,2,*

¹ Key Laboratory of Advanced Textile Materials & Manufacturing Technology, Ministry of Education; Engineering Research Center for Eco-Dyeing & Finishing of Textiles, Ministry of Education; National Base for International Science and Technology Cooperation in Textiles and Consumer-Goods Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China

² Silk Institute, College of Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 310018, China

³ Department of Bioengineering, University of Massachusetts Dartmouth, North Dartmouth, MA 02747, USA

Polymers 2018, 10(2), 128; https://doi.org/10.3390/polym10020128 - 29 Jan 2018

Cited by 17 | Viewed by 5674

Abstract

The influence of ethylene glycol methacrylate (EGMA) to the hydration and transition behaviors of thermo-responsive interpenetrating polymeric network (IPN) hydrogels containing sodium alginate, N-isopropylacrylamide (NIPAAm), and EGMA were investigated. The molar ratios of NIPAAm and EGMA were varied from 20:0 to 19.5:0.5 [...] Read more.

The influence of ethylene glycol methacrylate (EGMA) to the hydration and transition behaviors of thermo-responsive interpenetrating polymeric network (IPN) hydrogels containing sodium alginate, N-isopropylacrylamide (NIPAAm), and EGMA were investigated. The molar ratios of NIPAAm and EGMA were varied from 20:0 to 19.5:0.5 and 18.5:1.5 in the thermo-responsive alginate-Ca²⁺/P(NIPAAm-co-EGMA) IPN hydrogels. Due to the more hydrophilicity and high flexibility of EGMA, the IPN hydrogels exhibited higher lower critical solution temperature (LCST) and lower glass transition temperature (T_g) when the ratio of EGMA increases. The swelling/deswelling kinetics of the IPN hydrogels could be controlled by adjusting the NIPAAm/EGMA molar ratio. A faster water uptake rate and a slower water loss rate could be realized by increase the amount of EGMA in the IPN hydrogel (the shrinking rate constant was decreased from 0.01207 to 0.01195 and 0.01055 with the changing of NIPAAm/EGMA ratio from 20:0, 19.5:0.5 to 18.5:1.5). By using 2-Isopropylthioxanthone (ITX) as a photo initiator, the obtained alginate-Ca²⁺/P(NIPAAm-co-EGMA₃₆₀) IPN hydrogels were successfully immobilized on cotton fabrics. The surface and cross section of the hydrogel were probed by scanning electron microscopy (SEM). They all exhibited a porous structure, and the pore size was increased with the amount of EGMA. Moreover, the LCST values of the fabric-grafted hydrogels were close to those of the pure IPN hydrogels. Their thermal sensitivity remained unchanged. The cotton fabrics grafted with hydrogel turned out to be much softer with the continuous increase of EGMA amount. Therefore, compared with alginate-Ca²⁺/PNIPAAm hydrogel, alginate-Ca²⁺/P(NIPAAm-co-EGMA₃₆₀) hydrogel is a more promising candidate for wound dressing in the field of biomedical textile. Full article

(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)

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19 pages, 18122 KiB

Open AccessArticle

Permeability and Selectivity of PPO/Graphene Composites as Mixed Matrix Membranes for CO₂ Capture and Gas Separation

by Riccardo Rea¹

, Simone Ligi², Meganne Christian³, Vittorio Morandi³

, Marco Giacinti Baschetti¹

and Maria Grazia De Angelis^1,*

¹ Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali (DICAM), Università di Bologna, Via Terracini 28, 40131 Bologna, Italy

² Graphene XT s.r.l., 40131 Bologna, Italy

³ CNR-IMM Section of Bologna, via Gobetti, 101-40129 Bologna, Italy

Polymers 2018, 10(2), 129; https://doi.org/10.3390/polym10020129 - 29 Jan 2018

Cited by 45 | Viewed by 8285

Abstract

We fabricated novel composite (mixed matrix) membranes based on a permeable glassy polymer, Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), and variable loadings of few-layer graphene, to test their potential in gas separation and CO₂ capture applications. The permeability, selectivity and diffusivity of different gases as [...] Read more.

We fabricated novel composite (mixed matrix) membranes based on a permeable glassy polymer, Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), and variable loadings of few-layer graphene, to test their potential in gas separation and CO₂ capture applications. The permeability, selectivity and diffusivity of different gases as a function of graphene loading, from 0.3 to 15 wt %, was measured at 35 and 65 °C. Samples with small loadings of graphene show a higher permeability and He/CO₂ selectivity than pure PPO, due to a favorable effect of the nanofillers on the polymer morphology. Higher amounts of graphene lower the permeability of the polymer, due to the prevailing effect of increased tortuosity of the gas molecules in the membrane. Graphene also allows dramatically reducing the increase of permeability with temperature, acting as a “stabilizer” for the polymer matrix. Such effect reduces the temperature-induced loss of size-selectivity for He/N₂ and CO₂/N₂, and enhances the temperature-induced increase of selectivity for He/CO₂. The study confirms that, as observed in the case of other graphene-based mixed matrix glassy membranes, the optimal concentration of graphene in the polymer is below 1 wt %. Below such threshold, the morphology of the nanoscopic filler added in solution affects positively the glassy chains packing, enhancing permeability and selectivity, and improving the selectivity of the membrane at increasing temperatures. These results suggest that small additions of graphene to polymers can enhance their permselectivity and stabilize their properties. Full article

(This article belongs to the Special Issue Graphene-Polymer Composites)

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14 pages, 1777 KiB

Open AccessArticle

Thermal and Calorimetric Evaluations of Polyacrylonitrile Containing Covalently-Bound Phosphonate Groups

by Svetlana Tretsiakova-McNally^1,*

and Paul Joseph²

¹ Belfast School of Architecture and the Built Environment, Ulster University, Newtownabbey BT37 0QB, Northern Ireland, UK

² Centre for Environmental Safety and Risk Engineering, Victoria University, P.O. Box 14428, Melbourne, VIC 8001, Australia

Polymers 2018, 10(2), 131; https://doi.org/10.3390/polym10020131 - 30 Jan 2018

Cited by 25 | Viewed by 5587

Abstract

One of the effective ways to enhance flame retardance of polyacrylonitrile (PAN) is through a reactive route, primarily developed in our laboratories, which involved chemical modification reactions utilising phosphorus-containing comonomers. In the present study, diethyl(acryloyloxymethyl)phosphonate (DEAMP) and diethyl(1-acryloyloxyethyl)phosphonate (DE1AEP) were synthesised and copolymerised [...] Read more.

One of the effective ways to enhance flame retardance of polyacrylonitrile (PAN) is through a reactive route, primarily developed in our laboratories, which involved chemical modification reactions utilising phosphorus-containing comonomers. In the present study, diethyl(acryloyloxymethyl)phosphonate (DEAMP) and diethyl(1-acryloyloxyethyl)phosphonate (DE1AEP) were synthesised and copolymerised with acrylonitrile (AN), under radical initiation in an inert atmosphere, in aqueous slurries. The thermal degradation and combustion characteristics as well as the extent of flame retardation were mainly assessed with the aid of various thermo-analytical and calorimetric techniques. It was found that the incorporation of phosphonate groups in polymeric chains of PAN resulted in improved flame-retardant characteristics. Furthermore, it was observed that the actual chemical environment of the phosphorus atom in the acrylic phosphonate modifying groups has little effect on the overall thermal degradation and combustion behaviours of the modified PAN systems. It was also observed that the predominant mode of flame retardance occurred in the condensed phase. Full article

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15 pages, 1361 KiB

Open AccessArticle

Statistical Design of Experimental and Bootstrap Neural Network Modelling Approach for Thermoseparating Aqueous Two-Phase Extraction of Polyhydroxyalkanoates

by Yoong Kit Leong¹, Chih-Kai Chang², Senthil Kumar Arumugasamy³, John Chi-Wei Lan^2,*

, Hwei-San Loh⁴

, Dinie Muhammad⁵ and Pau Loke Show^1,*

¹ Bioseparation Research Group, Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia

² Biorefinery and Bioprocess Engineering Laboratory, Department of Chemical Engineering and Materials Science, Yuan Ze University, No. 135 Yuan-Tung Road, Chung-Li, Tao-Yuan 32003, Taiwan

³ Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia

⁴ School of Biosciences, Faculty of Science, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia

⁵ School of Chemical Engineering, University Sains Malaysia, Engineering Campus, Seri Ampangan, 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang, Malaysia

Polymers 2018, 10(2), 132; https://doi.org/10.3390/polym10020132 - 30 Jan 2018

Cited by 7 | Viewed by 5239

Abstract

At present, polyhydroxyalkanoates (PHAs) have been considered as a promising alternative to conventional plastics due to their diverse variability in structure and rapid biodegradation. To ensure cost competitiveness in the market, thermoseparating aqueous two-phase extraction (ATPE) with the advantages of being mild and [...] Read more.

At present, polyhydroxyalkanoates (PHAs) have been considered as a promising alternative to conventional plastics due to their diverse variability in structure and rapid biodegradation. To ensure cost competitiveness in the market, thermoseparating aqueous two-phase extraction (ATPE) with the advantages of being mild and environmental-friendly was suggested as the primary isolation and purification tool for PHAs. Utilizing two-level full factorial design, this work studied the influence and interaction between four independent variables on the partitioning behavior of PHAs. Based on the experimental results, feed forward neural network (FFNN) was used to develop an empirical model of PHAs based on the ATPE thermoseparating input-output parameter. In this case, bootstrap resampling technique was used to generate more data. At the conditions of 15 wt % phosphate salt, 18 wt % ethylene oxide–propylene oxide (EOPO), and pH 10 without the addition of NaCl, the purification and recovery of PHAs achieved a highest yield of 93.9%. Overall, the statistical analysis demonstrated that the phosphate concentration and thermoseparating polymer concentration were the most significant parameters due to their individual influence and synergistic interaction between them on all the response variables. The final results of the FFNN model showed the ability of the model to seamlessly generalize the relationship between the input–output of the process. Full article

(This article belongs to the Special Issue Polymers for Bioseparations)

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13 pages, 4974 KiB

Open AccessArticle

Preparation and Characterization of Graphene Oxide-Modified Sapium sebiferum Oil-Based Polyurethane Composites with Improved Thermal and Mechanical Properties

by Guiying Wu^†, Xiaoling Xu^†, Xin He and Yunjun Yan^*

¹ Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 133; https://doi.org/10.3390/polym10020133 - 30 Jan 2018

Cited by 37 | Viewed by 6539

Abstract

Bio-based polyurethane (PU) composites with superior thermal and mechanical properties have received wide attention. This is due to the recent rapid developments in the PU industry. In the work reported here, novel nano-composites with graphene oxide (GO)-modified Sapium sebiferum oil (SSO)-based PU has [...] Read more.

Bio-based polyurethane (PU) composites with superior thermal and mechanical properties have received wide attention. This is due to the recent rapid developments in the PU industry. In the work reported here, novel nano-composites with graphene oxide (GO)-modified Sapium sebiferum oil (SSO)-based PU has been synthesized via in situ polymerization. GO, prepared using the improved Hummers method from natural graphene (NG), and SSO-based polyol with a hydroxyl value of 211 mg KOH/g, prepared by lipase hydrolysis, were used as raw materials. The microstructures and properties of GO and the nano-composites were both characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile tests. The results showed that GO with its nano-sheet structure possessed a significant number of oxygen-containing functional groups at the surface. The nano-composites containing 1 wt % GO in the PU matrix (PU1) exhibited excellent comprehensive properties. Compared with those for pure PU, the glass transition temperature (T_g) and initial decomposition temperature (IDT) of the PU1 were enhanced by 14.1 and 31.8 °C, respectively. In addition, the tensile strength and Young’s modulus of the PU1 were also improved by 126% and 102%, respectively, compared to the pure PU. The significant improvement in both the thermal stability and mechanical properties for PU/GO composites was attributed to the homogeneous dispersion and good compatibility of GO with the PU matrix. The improvement in the properties upon the addition of GO may be attributable to the strong interfacial interaction between the reinforcing agent and the PU matrix. Full article

(This article belongs to the Special Issue Bio-Based Resins and Crosslinked Polymers from Renewable Resources)

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14 pages, 2260 KiB

Open AccessArticle

The Influence of the Morphology and Mechanical Properties of Polymer Inclusion Membranes (PIMs) on Zinc Ion Separation from Aqueous Solutions

by Katarzyna Witt^1,*

, Elzbieta Radzyminska-Lenarcik^1,*, Artur Kosciuszko², Magdalena Gierszewska³

and Kamil Ziuziakowski^4,5

¹ Faculty of Chemical Technology and Engineering, UTP University of Sciences and Technology, PL 85326 Bydgoszcz, Poland

² Faculty of Mechanical Engineering, UTP University of Sciences and Technology, PL 85796 Bydgoszcz, Poland

³ Faculty of Chemistry, Nicolaus Copernicus University in Torun, PL 87100 Torun, Poland

⁴ Faculty of Chemistry, Adam Mickiewicz University in Poznan, PL 61614 Poznan, Poland

⁵ Przedsiebiorstwo Wielobranzowe GALKOR Sp. z o.o., PL 86010 Koronowo, Poland

Polymers 2018, 10(2), 134; https://doi.org/10.3390/polym10020134 - 30 Jan 2018

Cited by 33 | Viewed by 5108

Abstract

The transport of Zn(II) ions across polymer inclusion membranes (PIMs) with acetylacetone (ACAC) or di(2-ethylhexyl)phosphoric acid (D₂EHPA) as carriers was studied. Polymeric membranes consisting of polyvinylchloride (PVC) as the support, bis(2-ethylhexyl)adipate (DAO) as plasticizer, and ACAC or D₂EHPA [...] Read more.

The transport of Zn(II) ions across polymer inclusion membranes (PIMs) with acetylacetone (ACAC) or di(2-ethylhexyl)phosphoric acid (D₂EHPA) as carriers was studied. Polymeric membranes consisting of polyvinylchloride (PVC) as the support, bis(2-ethylhexyl)adipate (DAO) as plasticizer, and ACAC or D₂EHPA as ion carriers were investigated. The highest recovery factors for Zn(II) ions were observed in the case of a membrane containing 20% acac (99.6%) and 60% D₂EHPA (56.3%). The prepared PIMs were examined using atomic force microscopy (AFM) techniques. Their mechanical properties were also determined. The influence of membrane morphology and mechanical properties on the zinc transport process was discussed. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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12 pages, 5374 KiB

Open AccessArticle

Paper Electrodes Coated with Partially-Exfoliated Graphite and Polypyrrole for High-Performance Flexible Supercapacitors

by Leping Huang¹, Weida Rao¹, Lingling Fan², Jie Xu^1,*, Zikui Bai¹, Weilin Xu^1,2 and Haifeng Bao^1,*

¹ State Key Laboratory for Hubei New Textile Materials and Advanced Processing Technology, School of Materials Science & Engineering, Wuhan Textile University, Wuhan 430200, China

² School of Textile Science & Engineering, Wuhan Textile University, Wuhan 430200, China

Polymers 2018, 10(2), 135; https://doi.org/10.3390/polym10020135 - 31 Jan 2018

Cited by 34 | Viewed by 6669

Abstract

Flexible paper electrodes for supercapacitors were prepared with partially-exfoliated graphite and polypyrrole as the active materials. Graphite was coated on paper with pencil drawing and then electrochemically exfoliated using the cyclic voltammetry (CV) technique to obtain the exfoliated graphite (EG)-coated paper (EG-paper). Polypyrrole [...] Read more.

Flexible paper electrodes for supercapacitors were prepared with partially-exfoliated graphite and polypyrrole as the active materials. Graphite was coated on paper with pencil drawing and then electrochemically exfoliated using the cyclic voltammetry (CV) technique to obtain the exfoliated graphite (EG)-coated paper (EG-paper). Polypyrrole (PPy) doped with β-naphthalene sulfonate anions was deposited on EG-paper through in-situ polymerization, leading to the formation of PPy-EG-paper. The as-prepared PPy-EG-paper showed a high electrical conductivity of 10.0 S·cm⁻¹ and could be directly used as supercapacitor electrodes. The PPy-EG-paper electrodes gave a remarkably larger specific capacitance of 2148 F∙g⁻¹ at a current density of 0.8 mA∙cm⁻², compared to PPy-graphite-paper (848 F∙g⁻¹). The capacitance value of PPy-EG-paper could be preserved by 80.4% after 1000 charge/discharge cycles. In addition, the PPy-EG-paper electrodes demonstrated a good rate capability and a high energy density of 110.3 Wh∙kg⁻¹ at a power density of 121.9 W∙kg⁻¹. This work will pave the way for the discovery of efficient paper-based electrode materials. Full article

(This article belongs to the Special Issue Soft Materials and Systems)

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12 pages, 5498 KiB

Open AccessArticle

PNIPAM-MAPOSS Hybrid Hydrogels with Excellent Swelling Behavior and Enhanced Mechanical Performance: Preparation and Drug Release of 5-Fluorouracil

by Peihong Li, Xiaoman Hou, Lijie Qu, Xueyan Dai and Chunling Zhang^*

Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Changchun 130022, China

Polymers 2018, 10(2), 137; https://doi.org/10.3390/polym10020137 - 31 Jan 2018

Cited by 40 | Viewed by 7129

Abstract

Poly(N-isopropylacrylamide) (PNIPAM) is a widely-studied polymers due to its excellent temperature sensitivity. PNIPAM-MAPOSS hybrid hydrogel, based on the introduction of acrylolsobutyl polyhedral oligomeric silsesquioxane (MAPOSS) into the PNIPAM matrix in the presence of polyethylene glycol, was prepared via radical polymerization. The [...] Read more.

Poly(N-isopropylacrylamide) (PNIPAM) is a widely-studied polymers due to its excellent temperature sensitivity. PNIPAM-MAPOSS hybrid hydrogel, based on the introduction of acrylolsobutyl polyhedral oligomeric silsesquioxane (MAPOSS) into the PNIPAM matrix in the presence of polyethylene glycol, was prepared via radical polymerization. The modified hydrogels exhibited a thick, heterogeneous porous structure. PEG was used as a pore-forming agent to adjust the pore size. MAPOSS reduced the swelling ratios of gels, and decreased the LCST, causing the hydrogels to shrink at lower temperatures. However, its hydrophobicity helped to improve the temperature response rate. The incorporation of rigid MAPOSS into the polymer network greatly increased the compressive modulus of the hydrogel. It is worth noting that, by adjusting the amount of MAPOSS and PEG, the hydrogel could have both ideal mechanical properties and swelling behavior. In addition, hydrogel containing 8.33 wt % MAPOSS could achieve stable and sustained drug release. Thus, the prepared PNIPAM-MAPOSS hybrid hydrogel can serve as drug carrier for 5-fluorouracil and may have potential application in other biomedical fields. Full article

(This article belongs to the Special Issue Siloxane-Based Polymers)

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14 pages, 1910 KiB

Open AccessArticle

Assessment of Axial Behavior of Circular HPFRCC Members Externally Confined with FRP Sheets

by Ugur Demir^*, Yusuf Sahinkaya, Medine Ispir and Alper Ilki

Civil Engineering Faculty, Istanbul Technical University, Maslak, Istanbul 34469, Turkey

Polymers 2018, 10(2), 138; https://doi.org/10.3390/polym10020138 - 31 Jan 2018

Cited by 4 | Viewed by 4685

Abstract

The aim of this paper is to identify the axial behavior characteristics of FRP (fiber reinforced polymer) confined circular HPFRCC (high performance fiber reinforced cementitious composite) members under compression. The test program comprised of 24 circular specimens with an average compressive strength of [...] Read more.

The aim of this paper is to identify the axial behavior characteristics of FRP (fiber reinforced polymer) confined circular HPFRCC (high performance fiber reinforced cementitious composite) members under compression. The test program comprised of 24 circular specimens with an average compressive strength of 102.7 MPa, including 21 carbon FRP (CFRP) confined (2, 4, 6, 8 and 10 layers) and three unconfined specimens. Transverse confinement generated by external FRP sheets resulted with a remarkable enhancement in axial strength and deformability, which is extremely important to resist seismic actions. The higher was the thickness of FRP confinement, the larger was the ultimate strain (ε_cu) and peak compressive strength (f′_cc) of externally confined HPFRCC. When compared to FRP confined conventional concrete, different axial and lateral deformation characteristics were seen in FRP jacketed HPFRCC members. Higher strength and steel fiber presence in HPFRCC limited the lateral deformations which resulted with reduced strain efficiency with respect to conventional concrete. After presenting the experimental work, performance and accuracy of several available models proposed for predicting the axial behavior of FRP jacketed concrete were evaluated in a comparative manner. Full article

(This article belongs to the Special Issue Selected Papers from "SMAR 2017")

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13 pages, 2321 KiB

Open AccessArticle

PLA Melt Stabilization by High-Surface-Area Graphite and Carbon Black

by Luciana D’Urso¹, Maria Rosaria Acocella¹

, Gaetano Guerra¹, Valentina Iozzino², Felice De Santis²

and Roberto Pantani^2,*

¹ Department of Chemistry and Biology, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy

² Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy

Polymers 2018, 10(2), 139; https://doi.org/10.3390/polym10020139 - 1 Feb 2018

Cited by 30 | Viewed by 5358

Abstract

Small amounts of carbon nanofillers, specifically high-surface-area graphite (HSAG) and more effectively carbon black (CB), are able to solve the well-known problem of degradation (molecular weight reduction) during melt processing, for the most relevant biodegradable polymer, namely poly(lactic acid), PLA. This behavior is [...] Read more.

Small amounts of carbon nanofillers, specifically high-surface-area graphite (HSAG) and more effectively carbon black (CB), are able to solve the well-known problem of degradation (molecular weight reduction) during melt processing, for the most relevant biodegradable polymer, namely poly(lactic acid), PLA. This behavior is shown by rheological measurements (melt viscosity during extrusion experiments and time sweep-complex viscosity) combined with gel permeation chromatography (GPC) experiments. PLA’s molecular weight, which is heavily reduced during melt extrusion of the neat polymer, can remain essentially unaltered by simple compounding with only 0.1 wt % of CB. At temperatures close to polymer melting by compounding with graphitic fillers, the observed stabilization of PLA melt could be rationalized by scavenging traces of water, which reduces hydrolysis of polyester bonds. Thermogravimetric analyses (TGA) indicate that the same carbon fillers, on the contrary, slightly destabilize PLA toward decomposition reactions, leading to the loss of volatile byproducts, which occur at temperatures higher than 300 °C, i.e., far from melt processing conditions. Full article

(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)

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17 pages, 7136 KiB

Open AccessArticle

Surface Hydrophilicity of Poly(l-Lactide) Acid Polymer Film Changes the Human Adult Adipose Stem Cell Architecture

by Chiara Argentati^1,†, Francesco Morena^1,†, Pia Montanucci²

, Marco Rallini³, Giuseppe Basta², Nicolino Calabrese⁴, Riccardo Calafiore²

, Marino Cordellini⁵, Carla Emiliani¹, Ilaria Armentano⁶ and Sabata Martino^1,*

¹ Department of Chemistry, Biology and Biotechnologies, Biochemistry and Molecular Biology Unit, University of Perugia, Via del Giochetto, 06126 Perugia, Italy

² Section of Cardiovascular, Endocrine and Metabolic Clinical Physiology, Laboratory for Endocrine Cell Transplants and Biohybrid Organs, Department of Medicine, University of Perugia, 06126 Perugia, Italy

³ Civil and Environmental Engineering Department, UdR INSTM, University of Perugia, 05100 Terni, Italy

⁴ Private Dental Practice, 06134 Perugia, Italy

⁵ Plastic and Reconstructive Surgery Unit, 06024 ASL 1 Umbria, Italy

⁶ Department of Ecological and Biological Sciences, Tuscia University, 01100 Viterbo, Italy

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 140; https://doi.org/10.3390/polym10020140 - 1 Feb 2018

Cited by 28 | Viewed by 6414

Abstract

Current knowledge indicates that the molecular cross-talk between stem cells and biomaterials guides the stem cells’ fate within a tissue engineering system. In this work, we have explored the effects of the interaction between the poly(l-lactide) acid (PLLA) polymer film and [...] Read more.

Current knowledge indicates that the molecular cross-talk between stem cells and biomaterials guides the stem cells’ fate within a tissue engineering system. In this work, we have explored the effects of the interaction between the poly(l-lactide) acid (PLLA) polymer film and human adult adipose stem cells (hASCs), focusing on the events correlating the materials’ surface characteristics and the cells’ plasma membrane. hASCs were seeded on films of pristine PLLA polymer and on a PLLA surface modified by the radiofrequency plasma method under oxygen flow (PLLA+O₂). Comparative experiments were performed using human bone-marrow mesenchymal stem cells (hBM-MSCs) and human umbilical matrix stem cells (hUCMSCs). After treatment with oxygen-plasma, the surface of PLLA films became hydrophilic, whereas the bulk properties were not affected. hASCs cultured on pristine PLLA polymer films acquired a spheroid conformation. On the contrary, hASCs seeded on PLLA+O₂ film surface maintained the fibroblast-like morphology typically observed on tissue culture polystyrene. This suggests that the surface hydrophilicity is involved in the acquisition of the spheroid conformation. Noteworthy, the oxygen treatment had no effects on hBM-MSC and hUCMSC cultures and both stem cells maintained the same shape observed on PLLA films. This different behavior suggests that the biomaterial-interaction is stem cell specific. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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25 pages, 6987 KiB

Open AccessArticle

Site-Specific DBCO Modification of DEC205 Antibody for Polymer Conjugation

by Simone Beck^1,2, Jennifer Schultze³, Hans-Joachim Räder³, Regina Holm¹, Meike Schinnerer⁴, Matthias Barz¹

, Kaloian Koynov³

and Rudolf Zentel^1,*

¹ Institute of Organic Chemistry, Johannes-Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany

² Graduate School Materials Science in Mainz, Staudingerweg 9, D-55128 Mainz, Germany

³ Max-Planck-Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany

⁴ Institute of Physical Chemistry, Jakob Welder Weg 11, D-55128 Mainz, Germany

Polymers 2018, 10(2), 141; https://doi.org/10.3390/polym10020141 - 2 Feb 2018

Cited by 17 | Viewed by 13957

Abstract

The design of multifunctional polymer-based vectors, forming pDNA vaccines, offers great potential in cancer immune therapy. The transfection of dendritic immune cells (DCs) with tumour antigen-encoding pDNA leads to an activation of the immune system to combat tumour cells. In this work, we [...] Read more.

The design of multifunctional polymer-based vectors, forming pDNA vaccines, offers great potential in cancer immune therapy. The transfection of dendritic immune cells (DCs) with tumour antigen-encoding pDNA leads to an activation of the immune system to combat tumour cells. In this work, we investigated the chemical attachment of DEC205 antibodies (aDEC205) as DC-targeting structures to polyplexes of P(Lys)-b-P(HPMA). The conjugation of a synthetic block copolymer and a biomacromolecule with various functionalities (aDEC205) requires bioorthogonal techniques to avoid side reactions. Click chemistry and in particular the strain-promoted alkyne-azide cycloaddition (SPAAC) can provide the required bioorthogonality. With regard to a SPAAC of both components, we firstly synthesized two different azide-containing block copolymers, P(Lys)-b-P(HPMA)-N₃(stat) and P(Lys)-b-P(HPMA)-N₃(end), for pDNA complexation. In addition, the site-specific incorporation of ring-strained dibenzocyclooctyne (DBCO) moieties to the DEC205 antibody was achieved by an enzymatic strategy using bacterial transglutaminase (BTG). The chemical accessibility of DBCO molecules within aDEC205 as well as the accessibility of azide-functionalities on the polyplex’ surface were investigated by various SPAAC experiments and characterized by fluorescence correlation spectroscopy (FCS). Full article

(This article belongs to the Special Issue Polymers for Therapy and Diagnostics)

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15 pages, 4930 KiB

Open AccessArticle

Study on the Nanomechanical and Nanotribological Behaviors of PEEK and CFRPEEK for Biomedical Applications

by Jian Song¹, Hongyu Shi¹, Zhenhua Liao², Song Wang², Yuhong Liu^1,*, Weiqiang Liu^1,2,* and Zhongxiao Peng³

¹ State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China

² Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China

³ School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, NSW 2052, Australia

Polymers 2018, 10(2), 142; https://doi.org/10.3390/polym10020142 - 2 Feb 2018

Cited by 23 | Viewed by 5024

Abstract

This study was to investigate the nanomechanical and nanotribological properties of polyether ether ketone (PEEK)-based composites for biomedical applications and to gain a fundamental understanding of the effects of carbon fibers in carbon-fiber-reinforced PEEK (CFRPEEK) on the mechanical properties and wear performance in [...] Read more.

This study was to investigate the nanomechanical and nanotribological properties of polyether ether ketone (PEEK)-based composites for biomedical applications and to gain a fundamental understanding of the effects of carbon fibers in carbon-fiber-reinforced PEEK (CFRPEEK) on the mechanical properties and wear performance in a microscale. Nanoindentation tests with a Berkovich indenter and nanoscratch experiments with a diamond stylus were performed on PEEK and CFRPEEK samples. The nanowear features and mechanisms of the tested samples were analyzed using 3D white-light interfering profilometry and scanning electron microscopy (SEM). The obtained results indicated that the reinforced carbon fibers increased the nanohardness and elastic modulus and decreased the friction coefficient and wear rate of PEEK. Different to many existing studies where a constant load was used in a nanoscratch test and the normal load was a key factor influencing the scratch performances of the tested specimens, stick–slip phenomena were observed on both PEEK and CFRPEEK in the nanoscratch tests with load increasing progressively. In constant load conditions, it was found that the major nanowear mechanisms of PEEK are adhesion, abrasion, and plastic deformation, while the nanowear mechanisms of CFRPEEK are dominated by severe adhesive wear, abrasive wear and mild fatigue. CFRPEEK has demonstrated superior nanomechanical and nanotribological performances, and hence can be considered a potential candidate for biomedical applications. Full article

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17 pages, 2953 KiB

Open AccessArticle

Vacuum Thermoforming Process: An Approach to Modeling and Optimization Using Artificial Neural Networks

by Wanderson De Oliveira Leite^1,*, Juan Carlos Campos Rubio², Francisco Mata Cabrera³, Angeles Carrasco⁴

and Issam Hanafi⁵

¹ Departamento de Mecânica, Instituto Federal de Educação, Ciência e Tecnologia de Minas Gerias—Campus Betim, Rua Itaguaçu, No. 595, São Caetano, 32677-780 Betim, Brazil

² Escola de Engenharia, Departamento de Engenharia Mecânica, Universidade Federal de Minas Gerais, Av. Pres. Antônio Carlos, No. 6627, Pampulha, 31270-901 Belo Horizonte, Brazil

³ Escuela de Ingeniería Minera e Industrial de Almadén, Departamento Mecánica Aplicada e Ingeniería de Proyectos, Universidad de Castilla-La Mancha, Plaza Manuel Meca No. 1, 13400 Ciudad Real, Spain

⁴ Escuela de Ingeniería Minera e Industrial de Almadén, Departamento de Filología Moderna, Universidad de Castilla-La Mancha, Plaza Manuel Meca No. 1, 13400 Ciudad Real, Spain

⁵ Ecole Nationale des Sciences Appliquées d’Al Hoceima (ENSAH), Département of Civil and Environmental Engineering, 32000 Al Hoceima, Morocco

Polymers 2018, 10(2), 143; https://doi.org/10.3390/polym10020143 - 2 Feb 2018

Cited by 29 | Viewed by 9034

Abstract

In the vacuum thermoforming process, the group effects of the processing parameters, when related to the minimizing of the product deviations set, have conflicting and non-linear values which make their mathematical modelling complex and multi-objective. Therefore, this work developed models of prediction and [...] Read more.

In the vacuum thermoforming process, the group effects of the processing parameters, when related to the minimizing of the product deviations set, have conflicting and non-linear values which make their mathematical modelling complex and multi-objective. Therefore, this work developed models of prediction and optimization using artificial neural networks (ANN), having the processing parameters set as the networks’ inputs and the deviations group as the outputs and, furthermore, an objective function of deviation minimization. For the ANN data, samples were produced in experimental tests of a product standard in polystyrene, through a fractional factorial design (2^k-p). Preliminary computational studies were carried out with various ANN structures and configurations with the test data until reaching satisfactory models and, afterwards, multi-criteria optimization models were developed. The validation tests were developed with the models’ predictions and solutions showed that the estimates for them have prediction errors within the limit of values found in the samples produced. Thus, it was demonstrated that, within certain limits, the ANN models are valid to model the vacuum thermoforming process using multiple parameters for the input and objective, by means of reduced data quantity. Full article

(This article belongs to the Special Issue Model-Based Polymer Processing)

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13 pages, 9719 KiB

Open AccessArticle

Preparation and Characterization of Porous Core-Shell Fibers for Slow Release of Tea Polyphenols

by Yaru Wang and Lan Xu^*

National Engineering Laboratory for Modern Silk, College of Textile and Engineering, Soochow University, 199 Ren-ai Road, Suzhou 215123, China

Polymers 2018, 10(2), 144; https://doi.org/10.3390/polym10020144 - 2 Feb 2018

Cited by 31 | Viewed by 7087

Abstract

This study focused on the fabrication, characterization, and release properties of electrospun tea polyphenol (TPP) loaded porous core-shell structured fibers. The morphology, structure and properties of the electrospun TPP loaded porous core-shell fibers were investigated by a combination of Fourier transformation infrared spectroscopy [...] Read more.

This study focused on the fabrication, characterization, and release properties of electrospun tea polyphenol (TPP) loaded porous core-shell structured fibers. The morphology, structure and properties of the electrospun TPP loaded porous core-shell fibers were investigated by a combination of Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM), contact angle (CA) measurements, transmission electron microscopy (TEM), etc. In addition, the cumulative drug release rate of TPP loaded porous core-shell fibers was determined by ultraviolet (UV) spectrophotometer, and the release mechanism was investigated using Fickian diffusion equation, which would provide the theoretical basis for future study. The results showed TPP loaded porous core-shell structured fibers were successfully prepared by coaxial electrospinning, and the porous structure of the core-shell fibers could further enlarge the specific surface area, enhance the hydrophobic properties, and improve the drug release properties. Full article

(This article belongs to the Special Issue Electrospinning of Nanofibres)

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14 pages, 6226 KiB

Open AccessArticle

Preloading Effect on Strengthening Efficiency of RC Beams Strengthened with Non- and Pretensioned NSM Strips

by Renata Kotynia^*

and Marta Przygocka

Department of Concrete Structures, Lodz University of Technology, 90-924 Lodz, Poland

Polymers 2018, 10(2), 145; https://doi.org/10.3390/polym10020145 - 3 Feb 2018

Cited by 5 | Viewed by 4030

Abstract

The near surface mounted (NSM) technique has been shown to be one of the most promising methods for upgrading reinforced concrete (RC) structures. Many tests carried out on RC members strengthened in flexure with NSM fiber-reinforced polymer (FRP) systems have demonstrated greater strengthening [...] Read more.

The near surface mounted (NSM) technique has been shown to be one of the most promising methods for upgrading reinforced concrete (RC) structures. Many tests carried out on RC members strengthened in flexure with NSM fiber-reinforced polymer (FRP) systems have demonstrated greater strengthening efficiency than the use of externally-bonded (EB) FRP laminates. Strengthening with simultaneous pretensioning of the FRP results in improvements in the serviceability limit state (SLS) conditions, including the increased cracking moment and decreased deflections. The objective of the reported experimental program, which consisted of two series of RC beams strengthened in flexure with NSM CFRP strips, was to investigate the influence of a number of parameters on the strengthening efficiency. The test program focused on an analysis of the effects of preloading on the strengthening efficiency which has been investigated very rarely despite being one of the most important parameters to be taken into account in strengthening design. Two preloading levels were considered: the beam self-weight only, which corresponded to stresses on the internal longitudinal reinforcement of 25% and 14% of the yield stress (depending on a steel reinforcement ratio), and the self-weight with the additional superimposed load, corresponding to 60% of the yield strength of the unstrengthened beam and a deflection equal to the allowable deflection at the SLS. The influence of the longitudinal steel reinforcement ratio was also considered in this study. To reflect the variability seen in existing structures, test specimens were varied by using different steel bar diameters. Finally, the impact of the composite reinforcement ratio and the number of pretensioned FRP strips was considered. Specimens were divided into two series based on their strengthening configuration: series “A” were strengthened with one pretensioned and two non-pretensioned carbon FRP (CFRP) strips, while series “B” were strengthened with two pretensioned strips. Experimental tests illustrated promising results at ultimate and serviceability limit state conditions. A significant gain of the load bearing capacity, in the range between 56% and 135% compared to the unstrengthened beams, was obtained. Tensile rupture of the NSM CFRP strips was achieved, confirming full utilization of the material. Full article

(This article belongs to the Special Issue Selected Papers from "SMAR 2017")

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17 pages, 42107 KiB

Open AccessArticle

Color Attributes of Colored-Yarn Mixed Woven Fabrics Made of Raw-White Warps and Multicolored Wefts and Based on Weft-Backed Structures

by Tao Hua^*

, Lau Yiu Tang, Wing Yan Chiu and Xiao Tian

Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Polymers 2018, 10(2), 146; https://doi.org/10.3390/polym10020146 - 5 Feb 2018

Cited by 8 | Viewed by 5259

Abstract

This paper reports the development of colored-yarn mixed woven fabrics by using raw white warps and multicolored-wefts, as well as a study of the influential factors on the color attributes of the resultant fabrics. Weft yarns in six colors, together with the white [...] Read more.

This paper reports the development of colored-yarn mixed woven fabrics by using raw white warps and multicolored-wefts, as well as a study of the influential factors on the color attributes of the resultant fabrics. Weft yarns in six colors, together with the white warp yarns, were used to create a series of fabric colors. Two types of new weft-backed structures were designed to assign the desired wefts for color mixing, as well as to reduce the white warp floats on the surface and thus, the lightness of the fabric. The effects of the proportion of yarn color components, weft density, and the introduction of black weft floats on the color attributes of fabrics, were investigated. The results show that through varying the proportion of mixing yarn color components, via fabric structure, a series of mixed red-blue and green-yellow colors for fabrics are created, respectively. Colored yarn mixed fabric presents a lowered lightness after a middle regulating layer is introduced into the structure. Compared to fabrics with a lower density, higher density fabrics possess lower lightness, higher redness and blueness in the blue-red fabrics, and higher greenness and yellowness in the yellow-green fabric. The lightness of fabric lowers after adding black yarn. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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14 pages, 4610 KiB

Open AccessArticle

An Investigation and Comparison of the Blending of LDPE and PP with Different Intrinsic Viscosities of PET

by Shi-Chang Chen, Li-Hao Zhang, Guo Zhang, Guo-Cai Zhong, Jian Li, Xian-Ming Zhang^* and Wen-Xing Chen

National Engineering Laboratory for Textile Fiber Materials and Processing Technology (Zhejiang), Zhejiang Sci-Tech University, Hangzhou 310018, China

Polymers 2018, 10(2), 147; https://doi.org/10.3390/polym10020147 - 5 Feb 2018

Cited by 28 | Viewed by 6725

Abstract

The blending of aliphatic polyolefins and aromatic poly(ethylene terephthalate) (PET) based on different intrinsic viscosities (IV) was conducted in a torque rheometer. The comparison of blend components in terms of low density polythene (LDPE) and polypropylene (PP) in blending with PET was investigated, [...] Read more.

The blending of aliphatic polyolefins and aromatic poly(ethylene terephthalate) (PET) based on different intrinsic viscosities (IV) was conducted in a torque rheometer. The comparison of blend components in terms of low density polythene (LDPE) and polypropylene (PP) in blending with PET was investigated, and the effects of the IV and proportion of PET on polymer blends are discussed in detail. Polymer blends with or without compatibilizer were examined by using a differential scanning calorimeter, thermogravimetric analyzer, rotary rheometer, field-emission scanning electron microscopy and a universal testing machine. It was found that the blending led to an increase in processability and a decrease in thermal stability for blends. The morphological analysis revealed that the incompatibility of blends was aggravated by a higher IV of PET, while this situation could be improved by the addition of compatibilizer. Results showed that there was an opposite effect for the tensile strength and the elongation at break of the polymer blend in the presence of a compatibilizer, wherein the influence of IV of PET was complicated. Full article

(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)

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16 pages, 7993 KiB

Open AccessArticle

Evolution of Filament-Shaped Porous Structure in Polycarbonate by Stretching under Carbon Dioxide

by Tomoaki Taguchi, Tomoe Hatakeyama, Ramu Miike and Hiromu Saito^*

Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588, Japan

Polymers 2018, 10(2), 148; https://doi.org/10.3390/polym10020148 - 5 Feb 2018

Cited by 1 | Viewed by 4277

Abstract

We found that a filament-shaped porous structure with periodic distance was obtained in polycarbonate for optical disk grade (OD-PC) film by stretching under compressed carbon dioxide (CO₂). The evolution of the characteristic porous structure was investigated by in situ observation during [...] Read more.

We found that a filament-shaped porous structure with periodic distance was obtained in polycarbonate for optical disk grade (OD-PC) film by stretching under compressed carbon dioxide (CO₂). The evolution of the characteristic porous structure was investigated by in situ observation during the stretching under compressed CO₂ and the optical microscopic observation of the stretched specimen. The voids were obtained under high CO₂ pressure as in the case of elevated temperature, suggesting that the evolution of the voids was caused by crazing due to chain disentanglement by accelerated molecular motion owing to the plasticization effect of CO₂. The filament-shaped voids were initiated at around the yielding point and increased continuously by nucleation in the matrix around the surface of the pre-existing voids. The shape of the voids did not change to an ellipsoidal one during stretching due to suppression of the craze opening by the hydrostatic pressure effect. The stretching of the CO₂-absorbed depressurized OD-PC revealed that the initiation of the voids was not only caused by the plasticization effect, but the hydrostatic pressure effect was also required. Full article

(This article belongs to the Special Issue Green Plasticizers for Polymers)

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21 pages, 2810 KiB

Open AccessArticle

Proteins as Nano-Carriers for Bioactive Compounds. The Case of 7S and 11S Soy Globulins and Folic Acid Complexation

by María Emilia Ochnio^1,†, Jimena H. Martínez^2,†, Mariana C. Allievi², Marcos Palavecino², Karina D. Martínez^3,* and Oscar E. Pérez^1,*

¹ Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Intendente Güiraldes, s/n, Ciudad Universitaria, Buenos Aires CP 1428, Argentina

² Consejo Nacional de Investigación Científica y Técnicas de la República Argentina IQUIBICEN-CONICET, Universidad de Buenos Aires, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Intendente Güiraldes, s/n, Ciudad Universitaria, Buenos Aires CP 1428, Argentina

³ Consejo Nacional de Investigación Científica y Técnicas de la República Argentina, CONICET, Universidad de Buenos Aires, Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Intendente Güiraldes, s/n, Ciudad Universitaria, Buenos Aires CP 1428, Argentina

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 149; https://doi.org/10.3390/polym10020149 - 5 Feb 2018

Cited by 41 | Viewed by 5225

Abstract

Isolated 7S and 11S globulins obtained from defeated soy flour were complexated with folic acid (FA) in order to generate nano-carriers for this important vitamin in human nutrition. Fluorescence spectroscopy and dynamic light scattering were applied to follow the nano-complexes formation and for [...] Read more.

Isolated 7S and 11S globulins obtained from defeated soy flour were complexated with folic acid (FA) in order to generate nano-carriers for this important vitamin in human nutrition. Fluorescence spectroscopy and dynamic light scattering were applied to follow the nano-complexes formation and for their characterization. Fluorescence experimental data were modeled by the Stern-Volmer and a modified double logarithm approach. The results obtained confirmed static quenching. The number of binding sites on the protein molecule was ~1. The values obtained for the binding constants suggest a high affinity between proteins and FA. Particle size distribution allowed to study the protein aggregation phenomenon induced by FA bound to the native proteins. Z-average manifested a clear trend to protein aggregation. 11S-FA nano-complexes resulted in more polydispersity. ζ-potential of FA nano-complexes did not show a remarkable change after FA complexation. The biological activity of nano-complexes loaded with FA was explored in terms of their capacity to enhance the biomass formation of Lactobacillus casei BL23. The results concerning to nano-complexes inclusion in culture media showed higher bacterial growth. Such a result was attributed to the entry of the acid by the specific receptors concomitantly by the peptide receptors. These findings have technological impact for the use of globulins-FA based nano-complexes in nutraceutical, pharmaceutical and food industries. Full article

(This article belongs to the Special Issue Protein Biopolymer)

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22 pages, 16947 KiB

Open AccessArticle

Facile Synthesis, Characterization of Poly-2-mercapto-1,3,4-thiadiazole Nanoparticles for Rapid Removal of Mercury and Silver Ions from Aqueous Solutions

by Shaojun Huang^1,*, Chengzhang Ma², Chao Li², Chungang Min¹, Ping Du¹, Yi Xia¹, Chaofen Yang¹ and Qiuling Huang¹

¹ Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093, China

² School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China

Polymers 2018, 10(2), 150; https://doi.org/10.3390/polym10020150 - 6 Feb 2018

Cited by 16 | Viewed by 4791

Abstract

Industrial pollution by heavy metal ions such as Hg²⁺ and Ag⁺ is a universal problem owing to the toxicity of heavy metals. In this study, a novel nano-adsorbent, i.e., poly-2-mercapto-1,3,4-thiadiazole (PTT), was synthesized and used to selectively adsorb mercury and silver [...] Read more.

Industrial pollution by heavy metal ions such as Hg²⁺ and Ag⁺ is a universal problem owing to the toxicity of heavy metals. In this study, a novel nano-adsorbent, i.e., poly-2-mercapto-1,3,4-thiadiazole (PTT), was synthesized and used to selectively adsorb mercury and silver ions from aqueous solutions. PTT nanoparticles were synthesized via chemical oxidative dehydrogenation polymerization under mild conditions. Oxidant species, medium, monomer concentration, oxidant/monomer molar ratio, and polymerization temperature were optimized to obtain optimum yields. The molecular structure and morphology of the nanoparticles were analyzed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), matrix-assisted laser desorption/ionization/time-of-flight (MALDI/TOF) mass and X-ray photoelectron (XPS) spectroscopies, wide-angle X-ray diffraction (WAXD), theoretical calculations and transmission electron microscopy (TEM), respectively. It was found that the polymerization of 2-mercapto-1,3,4-thiodiazole occurs through head-to-tail coupling between the S(2) and C(5) positions. The PTT nanoparticles having a peculiar synergic combination of four kinds of active groups, S–, –SH, N–N, and =N– with a small particle size of 30–200 nm exhibit ultrarapid initial adsorption rates of 1500 mg(Hg)·g⁻¹·h⁻¹ and 5364 mg(Ag)·g⁻¹·h⁻¹ and high adsorption capacities of up to 186.9 mg(Hg)·g⁻¹ and 193.1 mg(Ag)·g⁻¹, becoming ultrafast chelate nanosorbents with high adsorption capacities. Kinetic study indicates that the adsorption of Hg²⁺ and Ag⁺ follows the pseudo-second-order model, suggesting a chemical adsorption as the rate-limiting step during the adsorption process. The Hg²⁺ and Ag⁺-loaded PTT nanoparticles could be effectively regenerated with 0.1 mol·L⁻¹ EDTA or 1 mol·L⁻¹ HNO₃ without significantly losing their adsorption capacities even after five adsorption–desorption cycles. With these impressive properties, PTT nanoparticles are very promising materials in the fields of water-treatment and precious metals recovery. Full article

(This article belongs to the Special Issue Polymer-Based Nano-Sorbent Materials)

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13 pages, 2712 KiB

Open AccessArticle

Sortase-Mediated Ligation of Purely Artificial Building Blocks

by Xiaolin Dai^1,2,‡, Diana M. Mate^3,†,‡, Ulrich Glebe^1,2,‡, Tayebeh Mirzaei Garakani^3,4, Andrea Körner³, Ulrich Schwaneberg^3,4,* and Alexander Böker^1,2,*

¹ Fraunhofer Institute for Applied Polymer Research IAP, Geiselbergstr. 69, 14476 Potsdam-Golm, Germany

² Lehrstuhl für Polymermaterialien und Polymertechnologie, University of Potsdam, 14476 Potsdam-Golm, Germany

³ DWI—Leibniz Institute for Interactive Materials e.V., Forckenbeckstr. 50, 52056 Aachen, Germany

⁴ Institute of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany

^† Current address: Center of Molecular Biology “Severo Ochoa”, Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain.

^‡ These authors contributed equally to this work.

Polymers 2018, 10(2), 151; https://doi.org/10.3390/polym10020151 - 6 Feb 2018

Cited by 12 | Viewed by 6987

Abstract

Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica [...] Read more.

Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica nanoparticles (NPs), poly(ethylene glycol) and poly(N-isopropyl acrylamide) are chosen as synthetic building blocks. As a proof of concept, NP–polymer, NP–NP, and polymer–polymer structures are formed by SrtA catalysis. Therefore, the building blocks are equipped with the recognition sequence needed for SrtA reaction—the conserved peptide LPETG—and a pentaglycine motif. The successful formation of the reaction products is shown by means of transmission electron microscopy (TEM), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS), and dynamic light scattering (DLS). The sortase catalyzed linkage of artificial building blocks sets the stage for the development of a new approach to link synthetic structures in cases where their synthesis by established chemical methods is complicated. Full article

(This article belongs to the Special Issue Polymer Hybrid Materials)

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14 pages, 10940 KiB

Open AccessArticle

Effect of Load on the Thermal Expansion Behavior of T700 Carbon Fiber Bundles

by Guoliang Geng^1,*, Xiaofei Ma^2,*, Hongbin Geng¹ and Yiyong Wu¹

¹ School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

² CAST-Xi’an Institute of Space Radio Technology, Xi’an 710100, China

Polymers 2018, 10(2), 152; https://doi.org/10.3390/polym10020152 - 6 Feb 2018

Cited by 5 | Viewed by 5819

Abstract

T700 carbon fiber bundles (CFBs) are the primary material used for manufacturing cable-net in a deployable antenna. In this paper, the relationships between the coefficient of thermal expansion (CTE) of T700 CFBs and the experimental load were investigated. The microstructure of T700 CFBs [...] Read more.

T700 carbon fiber bundles (CFBs) are the primary material used for manufacturing cable-net in a deployable antenna. In this paper, the relationships between the coefficient of thermal expansion (CTE) of T700 CFBs and the experimental load were investigated. The microstructure of T700 CFBs was analyzed with Raman spectra and XRD before and after the thermomechanical test. The measured results indicated that the T700 CFBs that were parallel to the axis had negative expansion characteristics when in a temperature range of −150–+150 °C. The thermal strain that occurred during the heating and the cooling thermal cycles had an unclosed curve that served as the loop. When the thermal cycles were the same, the position of the strain loop and the length of the sample exhibited regular change. The average of the CTEs decreased as the experimental load increased. The microstructural analysis suggested that the degree of structural order and the degree of orientation along the fiber axis improved with the experimental load increase. The change of microstructure parameters could be the primary cause of the negative CTE’s variation within the T700 CFBs. The experimental results provide some guidelines for improving the cable-net material selection. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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11 pages, 3567 KiB

Open AccessArticle

Silk Fibroin/Polyvinyl Pyrrolidone Interpenetrating Polymer Network Hydrogels

by Dajiang Kuang¹, Feng Wu¹, Zhuping Yin¹, Tian Zhu¹, Tieling Xing¹, Subhas C. Kundu²

and Shenzhou Lu^1,*

¹ National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, China

² 3Bs Research Group, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, University of Minho, AvePark, Barco, 4805-017 Guimaraes, Portugal

Polymers 2018, 10(2), 153; https://doi.org/10.3390/polym10020153 - 6 Feb 2018

Cited by 33 | Viewed by 7344

Abstract

Silk fibroin hydrogel is an ideal model as biomaterial matrix due to its excellent biocompatibility and used in the field of medical polymer materials. Nevertheless, native fibroin hydrogels show poor transparency and resilience. To settle these drawbacks, an interpenetrating network (IPN) of hydrogels [...] Read more.

Silk fibroin hydrogel is an ideal model as biomaterial matrix due to its excellent biocompatibility and used in the field of medical polymer materials. Nevertheless, native fibroin hydrogels show poor transparency and resilience. To settle these drawbacks, an interpenetrating network (IPN) of hydrogels are synthesized with changing ratios of silk fibroin/N-Vinyl-2-pyrrolidonemixtures that crosslink by H₂O₂ and horseradish peroxidase. Interpenetrating polymer network structure can shorten the gel time and the pure fibroin solution gel time for more than a week. This is mainly due to conformation from the random coil to the β-sheet structure changes of fibroin. Moreover, the light transmittance of IPN hydrogel can be as high as more than 97% and maintain a level of 90% within a week. The hydrogel, which mainly consists of random coil, the apertures inside can be up to 200 μm. Elastic modulus increases during the process of gelation. The gel has nearly 95% resilience under the compression of 70% eventually, which is much higher than native fibroin gel. The results suggest that the present IPN hydrogels have excellent mechanical properties and excellent transparency. Full article

(This article belongs to the Special Issue Protein Biopolymer)

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17 pages, 4484 KiB

Open AccessArticle

Preparation and Properties of High Solid Content and Low Viscosity Waterborne Polyurethane—Acrylate Emulsion with a Reactive Emulsifier

by Zhewen Zhu

, Ruiqi Li, Chaoying Zhang and Shuling Gong^*

College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China

Polymers 2018, 10(2), 154; https://doi.org/10.3390/polym10020154 - 6 Feb 2018

Cited by 52 | Viewed by 8394

Abstract

High solid content waterborne polyurethane-acrylate (WPUA) emulsions have been successfully synthesized in two steps. Firstly, we prepared a waterborne polyurethane emulsion, then reacted it with acrylate monomer by emulsion polymerization using the semi-continuous seeded method. The effects of the type and amount of [...] Read more.

High solid content waterborne polyurethane-acrylate (WPUA) emulsions have been successfully synthesized in two steps. Firstly, we prepared a waterborne polyurethane emulsion, then reacted it with acrylate monomer by emulsion polymerization using the semi-continuous seeded method. The effects of the type and amount of emulsifier, the amount of dimethylolpropionic acid (DMPA), the choice of capping group, the ratio of PU/PA, and the method of adding a water-soluble monomer to the properties of the composite emulsion were investigated. The reactive emulsifier replaced the traditional emulsifier and there were no metal ions introduced to the reaction, whether by the emulsifier or the initiator. Through a variety of tests, we proved that the prepared emulsion has the advantages of small particle size, narrow distribution, good stability, good performance of the film, and solid content of 46%. Full article

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11 pages, 2001 KiB

Open AccessArticle

Catechol End-Functionalized Polylactide by Organocatalyzed Ring-Opening Polymerization

by Naroa Sadaba^1,2, Maitane Salsamendi¹, Nerea Casado¹

, Ester Zuza²

, Jone Muñoz², Jose-Ramon Sarasua²

, David Mecerreyes^1,3

, Daniele Mantione¹

, Christophe Detrembleur⁴ and Haritz Sardon^1,3,*

¹ POLYMAT, University of the Basque Country UPV/EHU, Joxe Maria Korta Center, Avenida Tolosa 72, 20018 Donostia/SanSebastian, Spain

² Department of Mining-Metallurgy Engineering and Materials Science, POLYMAT, University of the Basque Country UPV/EHU, School of Engineering, Alameda de Urquijo s/n, 48013 Bilbao, Spain

³ IKERBASQUE Basque Foundation for Science, Maria Diaz de Haro 3, E-48011 Bilbao, Spain

⁴ Center for Education and Research on Macromolecules (CERM), CESAM Research Unit, University of Liège (ULg), Sart Tilman B6a, Liège, Belgium

Polymers 2018, 10(2), 155; https://doi.org/10.3390/polym10020155 - 6 Feb 2018

Cited by 15 | Viewed by 6774

Abstract

There is a great interest in incorporating catechol moieties into polymers in a controlled manner due to their interesting properties, such as the promotion of adhesion, redox activity or bioactivity. One possibility is to incorporate the catechol as end-group in a polymer chain [...] Read more.

There is a great interest in incorporating catechol moieties into polymers in a controlled manner due to their interesting properties, such as the promotion of adhesion, redox activity or bioactivity. One possibility is to incorporate the catechol as end-group in a polymer chain using a functional initiator by means of controlled polymerization strategies. Nevertheless, the instability of catechol moieties under oxygen and basic pH requires tedious protection and deprotection steps to perform the polymerization in a controlled fashion. In the present work, we explore the organocatalyzed synthesis of catechol end-functional, semi-telechelic polylactide (PLLA) using non-protected dopamine, catechol molecule containing a primary amine, as initiator. NMR and SEC-IR results showed that in the presence of a weak organic base such as triethylamine, the ring-opening polymerization (ROP) of lactide takes place in a controlled manner without need of protecting the cathechol units. To further confirm the end-group fidelity the catechol containing PLLA was characterized by Cyclic Voltammetry and MALDI-TOF confirming the absence of side reaction during the polymerization. In order to exploit the potential of catechol moieties, catechol end-group of PLLA was oxidized to quinone and further reacted with aliphatic amines. In addition, we also confirmed the ability of catechol functionalized PLLA to reduce metal ions to metal nanoparticles to obtain well distributed silver nanoparticles. It is expected that this new route of preparing catechol-PLLA polymers without protection will increase the accessibility of catechol containing biodegradable polymers by ROP. Full article

(This article belongs to the Special Issue New Developments in Ring-Opening Polymerization)

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13 pages, 2956 KiB

Open AccessArticle

Compression Creep and Thermal Ratcheting Behavior of High Density Polyethylene (HDPE)

by Rahul Palaniappan Kanthabhabha Jeya^*

and Abdel-Hakim Bouzid

Department of Mechanical engineering, École de Technologie Supérieure, 1100 Notre Dame O, Montréal, QC H3C1K3, Canada

Polymers 2018, 10(2), 156; https://doi.org/10.3390/polym10020156 - 7 Feb 2018

Cited by 22 | Viewed by 9569

Abstract

The characterization of thermal ratcheting behavior of high density polyethylene (HDPE) material coupled with compressive creep is presented. The research explores the adverse influence of thermal cycling on HDPE material properties under the effect of compressive load, number of thermal cycles, creep time [...] Read more.

The characterization of thermal ratcheting behavior of high density polyethylene (HDPE) material coupled with compressive creep is presented. The research explores the adverse influence of thermal cycling on HDPE material properties under the effect of compressive load, number of thermal cycles, creep time period, and thermal ratcheting temperature range. The compressive creep analysis of HDPE shows that the magnitude of creep strain increases with increase in magnitude of applied load and temperature, respectively. The creep strain value increased by 7 and 28 times between least and maximum applied temperature and load conditions, respectively. The creep modulus decreases with increase in compressive load and temperature conditions. The cumulative deformation is evident in the HDPE material, causing a reduction in the thickness of the sample under thermal ratcheting. The loss of thickness increases with increase in the number of thermal cycles, while showing no sign of saturation. The thermal ratcheting strain (TRS) is influenced dominantly by the applied load condition. In addition, the TRS decreases with increase in creep time period, which is cited to the extended damage induced due creep. The results highlight the need for improved design standard with inclusion of thermal ratcheting phenomenon for HDPE structures particularly HDPE bolted flange joint. Full article

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19 pages, 4218 KiB

Open AccessArticle

Effects of Cyclodextrins (β and γ) and l-Arginine on Stability and Functional Properties of Mucoadhesive Buccal Films Loaded with Omeprazole for Pediatric Patients

by Sajjad Khan and Joshua Boateng^*

Department of Pharmaceutical, Chemical and Environmental Sciences, Faculty of Engineering and Science, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK

Polymers 2018, 10(2), 157; https://doi.org/10.3390/polym10020157 - 7 Feb 2018

Cited by 23 | Viewed by 5514

Abstract

Omeprazole (OME) is employed for treating ulcer in children, but is unstable and exhibits first pass metabolism via the oral route. This study aimed to stabilize OME within mucoadhesive metolose (MET) films by combining cyclodextrins (CD) and l-arginine (l-arg) as [...] Read more.

Omeprazole (OME) is employed for treating ulcer in children, but is unstable and exhibits first pass metabolism via the oral route. This study aimed to stabilize OME within mucoadhesive metolose (MET) films by combining cyclodextrins (CD) and l-arginine (l-arg) as stabilizing excipients and functionally characterizing for potential delivery via the buccal mucosa of paediatric patients. Polymeric solutions at a concentration of 1% w/w were obtained by dispersing the required weight of metolose in 20% v/v ethanol as solvent at a temperature of 40 °C using polyethylene glycol (PEG 400) (0.5% w/w) as plasticizer. The films were obtained by drying the resulting polymer solutions at in an oven at 40 °C. Textural (tensile and mucoadhesion) properties, physical form (differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy), residual moisture content (thermogravimetric analysis (TGA)) and surface morphology (scanning electron microscopy (SEM)) were investigated. Optimized formulations containing OME, CDs (β or γ) and l-arg (1:1:1) were selected to investigate the stabilization of the drug. The DSC, XRD, and FTIR showed possible molecular dispersion of OME in metolose film matrix. Plasticized MET films containing OME:βCD:l-arg 1:1:1 were optimum in terms of transparency and ease of handling and therefore further functionally characterized (hydration, mucoadhesion, in vitro drug dissolution and long term stability studies). The optimized formulation showed sustained drug release that was modelled by Korsmeyer–Peppas equation, while the OME showed stability under ambient temperature conditions for 28 days. The optimized OME loaded MET films stabilized with βCD and l-arg have potential for use as paediatric mucoadhesive buccal delivery system, which avoids degradation in the stomach acid as well as first pass metabolism in the liver. Full article

(This article belongs to the Special Issue Advances in Mucoadhesive Polymers and Formulations for Transmucosal Drug Delivery)

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22 pages, 16284 KiB

Open AccessArticle

The Effect of Irradiation on Mechanical and Thermal Properties of Selected Types of Polymers

by David Manas^1,2,†, Martin Ovsik^1,2,*

, Ales Mizera²

, Miroslav Manas², Lenka Hylova^1,2, Martin Bednarik¹

and Michal Stanek^1,2

¹ Tomas Bata University in Zlin, Faculty of Technology, Vavreckova 275, 760 01 Zlín, Czech Republic

² Tomas Bata University in Zlin, Faculty of Applied Informatics, CEBIA-Tech, Nad Stranemi 4511, 760 05 Zlin, Czech Republic

^† This article is dedicated, in memoriam, to Assoc. Prof. David Manas.

Polymers 2018, 10(2), 158; https://doi.org/10.3390/polym10020158 - 7 Feb 2018

Cited by 60 | Viewed by 10986

Abstract

This article deals with the influence of electron-beam radiation on the micro-mechanical, thermo-mechanical, and structural properties of selected polymers. In the search for the desired improvement of polymers, it is possible to use, inter alia, one particular possible modification—Namely, crosslinking—Which is a process [...] Read more.

This article deals with the influence of electron-beam radiation on the micro-mechanical, thermo-mechanical, and structural properties of selected polymers. In the search for the desired improvement of polymers, it is possible to use, inter alia, one particular possible modification—Namely, crosslinking—Which is a process during which macromolecular chains start to connect to each other and, thus, create the spatial network in the structure. In the course of the treatment of the ionizing radiation, two actions can occur: crosslinking and scission of macromolecules, or degradation. Both these processes run in parallel. Using the crosslinking technology, standard and technical polymers can acquire the more “expensive” high-tech polymeric material properties and, thus, replace these materials in many applications. The polymers that were tested were selected from across the whole spectra of thermoplastics, ranging from commodity polymers, technical polymers, as well as high-performance polymers. These polymers were irradiated by different doses of beta radiation (33, 66, 99, 132, 165, and 198 kGy). The micro-mechanical and thermo-mechanical properties of these polymers were measured. When considering the results, it is obvious that irradiation acts on each polymer differently but, always when the optimal dose was found, the mechanical properties increased by up to 36%. The changes of micro-mechanical and thermo-mechanical properties were confirmed by structural measurement when the change of the micro-hardness and modulus corresponded to the crystalline phase change as determined by X-ray and gel content. Full article

(This article belongs to the Special Issue Model-Based Polymer Processing)

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16 pages, 5692 KiB

Open AccessArticle

Preparation of 2-Aminothiazole-Functionalized Poly(glycidyl methacrylate) Microspheres and Their Excellent Gold Ion Adsorption Properties

by Chao Xiong¹, Shixing Wang^1,2,*, Libo Zhang^1,2, Ying Li¹, Yang Zhou³ and Jinhui Peng^1,2

¹ Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China

² State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, China

³ School of Textile Science and Engineering, Wuhan Textile University, Wuhan 430200, China

Polymers 2018, 10(2), 159; https://doi.org/10.3390/polym10020159 - 8 Feb 2018

Cited by 43 | Viewed by 4742

Abstract

A new adsorbent(A-PGMA) has been synthesized via functionalizing poly(glycidyl methacrylate) microsphere with 2-aminothiazole and used to adsorb gold ions from aqueous solutions. The adsorbent was characterized by X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), Zeta potential, scanning electron microscope (SEM) and Fourier transform infrared [...] Read more.

A new adsorbent(A-PGMA) has been synthesized via functionalizing poly(glycidyl methacrylate) microsphere with 2-aminothiazole and used to adsorb gold ions from aqueous solutions. The adsorbent was characterized by X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), Zeta potential, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The influence factors such as the pH value of the solution, the initial gold ion concentration and the contact time were examined. Simultaneously, the adsorption process of the gold ion on A-PGMA fitted well with the Langmuir and pseudo-second-order models, respectively. The results showed that the maximum adsorption capacity was 440.54 mg/g and the equilibrium time of adsorption was about 3 h under pH 4. Moreover, the adsorbent has a high reusability after five cycles and good selectivity from coexisting ions, including Zn(II), Mg(II), Cu(II), Ge(IV) and B(III). The adsorption mechanisms of gold ions were ion exchange and chelation between the sulfur and nitrogen groups on the surface of A-PGMA and AuCl₄⁻. Therefore, the adsorbent has a great potential for adsorption of gold ions from aqueous solutions. Full article

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16 pages, 2473 KiB

Open AccessArticle

Production and Characterization of a Clotrimazole Liposphere Gel for Candidiasis Treatment

by Elisabetta Esposito^1,*

, Maddalena Sguizzato¹, Christian Bories²

, Claudio Nastruzzi¹ and Rita Cortesi¹

¹ Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara, Italy

² Antiparasitic Chemotherapy-CNRS 8076, Faculty of Pharmacy, F-92296 Chatenay-Malabry CEDEX, France

Polymers 2018, 10(2), 160; https://doi.org/10.3390/polym10020160 - 8 Feb 2018

Cited by 17 | Viewed by 6016

Abstract

This study describes the design and characterization of a liposphere gel containing clotrimazole for the treatment of Candida albicans. Lipospheres were produced by the melt-dispersion technique, using a lipid phase constituted of stearic triglyceride in a mixture with caprylic/capric triglyceride or an [...] Read more.

This study describes the design and characterization of a liposphere gel containing clotrimazole for the treatment of Candida albicans. Lipospheres were produced by the melt-dispersion technique, using a lipid phase constituted of stearic triglyceride in a mixture with caprylic/capric triglyceride or an alkyl lactate derivative. The latter component was added to improve the action of clotrimazole against candida. The liposphere morphology and dimensional distribution were evaluated by scanning electron microscopy. Clotrimazole release kinetics was investigated by an in vitro dialysis method. An anticandidal activity study was conducted on the lipospheres. To obtain formulations with suitable viscosity for vaginal application, the lipospheres were added to a xanthan gum gel. The rheological properties, spreadability, leakage, and adhesion of the liposphere gel were investigated. Clotrimazole encapsulation was always over 85% w/w. The anticandidal study demonstrated that the encapsulation of clotrimazole in lipospheres increased its activity against Candida albicans, especially in the presence of the alkyl lactate derivative in the liposphere matrix. A dialysis method demonstrated that clotrimazole was slowly released from the liposphere gel and that the alkyl lactate derivative further controlled clotrimazole release. Adhesion and leakage tests indicated a prolonged adhesion of the liposphere gel, suggesting its suitability for vaginal application. Full article

(This article belongs to the Special Issue Advances in Mucoadhesive Polymers and Formulations for Transmucosal Drug Delivery)

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13 pages, 9480 KiB

Open AccessArticle

Time-Resolving Study of Stress-Induced Transformations of Isotactic Polypropylene through Wide Angle X-ray Scattering Measurements

by Finizia Auriemma^1,*

, Claudio De Rosa¹

, Rocco Di Girolamo¹

, Anna Malafronte¹, Miriam Scoti¹, Geoffrey Robert Mitchell²

and Simona Esposito¹

¹ Dipartimento di Scienze Chimiche, Università di Napoli “Federico II”, Complesso Monte Sant’ Angelo, via Cintia, 80126 Napoli, Italy

² CDRSP—Centre for Rapid and Sustainable Product Development, Polytechnic Institute of Leiria, Centro Empresarial da Marinha Grande, 2430-028 Marinha Grande, Portugal

Polymers 2018, 10(2), 162; https://doi.org/10.3390/polym10020162 - 8 Feb 2018

Cited by 27 | Viewed by 5694

Abstract

The development of a highly oriented fiber morphology by effect of tensile deformation of stereodefective isotactic polypropylene (iPP) samples, starting from the unoriented γ form, is studied by following the transformation in real time during stretching through wide angle X-ray scattering (WAXS) measurements. [...] Read more.

The development of a highly oriented fiber morphology by effect of tensile deformation of stereodefective isotactic polypropylene (iPP) samples, starting from the unoriented γ form, is studied by following the transformation in real time during stretching through wide angle X-ray scattering (WAXS) measurements. In the stretching process, after yielding, the initial γ form transforms into the mesomorphic form of iPP through mechanical melting and re-crystallization. The analysis of the scattering invariant measured in the WAXS region highlights that the size of the mesomorphic domains included in the well oriented fiber morphology obtained at high deformations increases through a process which involves the coalescence of the small fragments formed by effect of tensile stress during lamellar destruction with the domain of higher dimensions. Full article

(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)

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13 pages, 5038 KiB

Open AccessArticle

Surface-Engineered Nanocontainers Based on Molecular Self-Assembly and Their Release of Methenamine

by Minghui Zhang^1,2

, Jinben Wang^1,*, Pei Zhang^1,* and Haike Yan¹

¹ Beijing National Laboratory for Molecular Sciences, Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Polymers 2018, 10(2), 163; https://doi.org/10.3390/polym10020163 - 8 Feb 2018

Cited by 3 | Viewed by 4145

Abstract

The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous functional properties. To fabricate controllable assembling nanocomposites for efficiently encapsulating methenamine and releasing them on demand, we functionalized the surface of natural halloysite nanotubes (HNTs) selectively with [...] Read more.

The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous functional properties. To fabricate controllable assembling nanocomposites for efficiently encapsulating methenamine and releasing them on demand, we functionalized the surface of natural halloysite nanotubes (HNTs) selectively with polymerizable gemini surfactant which has peculiar aggregation behavior, aiming at endowing the nanomaterials with self-assembly and stimulative responsiveness characteristics. The micromorphology, grafted components and functional groups were identified using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The created nanocomposites presented various characteristics of methenamine release with differences in the surface composition. It is particularly worth mentioning that the controlled release was more efficient with the increase of geminized monomer proportion, which is reasonably attributed to the fact that the amphiphilic geminized moieties with positive charge and obvious hydrophobic interactions interact with the outer and inner surface in different ways through fabricating polymeric shell as release stoppers at nanotube ends and forming polymer brush into the nanotube lumen for guest immobilization. Meanwhile, the nanocomposites present temperature and salinity responsive characteristics for the release of methenamine. The combination of HNTs with conjugated functional polymers will open pathways for engineering flexible composites which are promising for application in controlled release fields. Full article

(This article belongs to the Special Issue Stimuli Responsive Polymers)

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21 pages, 1910 KiB

Open AccessArticle

Dynamics of a Complex Multilayer Polymer Network: Mechanical Relaxation and Energy Transfer

by Aurel Jurjiu^1,*, Flaviu Turcu¹

and Mircea Galiceanu²

¹ Faculty of Physics, Babes-Bolyai University, Street Mihail Kogalniceanu 1, 400084 Cluj-Napoca, Romania

² Department of Physics, Federal University of Amazonas, 69077-000 Manaus, Brazil

Polymers 2018, 10(2), 164; https://doi.org/10.3390/polym10020164 - 8 Feb 2018

Cited by 4 | Viewed by 3339

Abstract

In this paper, we focus on the mechanical relaxation of a multilayer polymer network built by connecting identical layers that have, as underlying topologies, the dual Sierpinski gasket and the regular dendrimer. Additionally, we analyze the dynamics of dipolar energy transfer over a [...] Read more.

In this paper, we focus on the mechanical relaxation of a multilayer polymer network built by connecting identical layers that have, as underlying topologies, the dual Sierpinski gasket and the regular dendrimer. Additionally, we analyze the dynamics of dipolar energy transfer over a system of chromophores arranged in the form of a multilayer network. Both dynamical processes are studied in the framework of the generalized Gaussian structure (GSS) model. We develop a method whereby the whole eigenvalue spectrum of the connectivity matrix of the multilayer network can be determined iteratively, thereby rendering possible the analysis of the dynamics of networks consisting of a large number of layers. This fact allows us to study in detail the crossover from layer-like behavior to chain-like behavior. Remarkably, we highlight the existence of two bulk-like behaviors. The theoretical findings with respect to the decomposition of the intermediate domain of the relaxation quantities, as well as the chain-like behavior, are well supported by experimental results. Full article

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11 pages, 2027 KiB

Open AccessArticle

Anion-Controlled Architecture and Photochromism of Naphthalene Diimide-Based Coordination Polymers

by Jian-Jun Liu^*, Shu-Biao Xia, Yu-Lian Duan, Teng Liu, Fei-Xiang Cheng and Cheng-Ke Sun

Center for Yunnan-Guizhou Plateau Chemical Functional Materials and Pollution Control, Qujing Normal University, Qujing 655011, China

Polymers 2018, 10(2), 165; https://doi.org/10.3390/polym10020165 - 8 Feb 2018

Cited by 89 | Viewed by 5867

Abstract

Three new cadmium coordination polymers, namely [Cd(NO₃)₂(DPNDI)(CH₃OH)]·CH₃OH (1), [Cd(SCN)₂(DPNDI)] (2), and [Cd(DPNDI)₂(DMF)₂]·2ClO₄ (3) (DPNDI = N,N-di(4-pyridyl)-1,4,5,8-naphthalene diimide, DMF = [...] Read more.

Three new cadmium coordination polymers, namely [Cd(NO₃)₂(DPNDI)(CH₃OH)]·CH₃OH (1), [Cd(SCN)₂(DPNDI)] (2), and [Cd(DPNDI)₂(DMF)₂]·2ClO₄ (3) (DPNDI = N,N-di(4-pyridyl)-1,4,5,8-naphthalene diimide, DMF = N,N-dimethylformamide) have been synthesized by reactions of DPNDI with Cd(NO₃)₂, Cd(SCN)₂, and Cd(ClO₄)₂, respectively. Compound 1 is a one-dimensional coordination polymer with strong lone pair-π interactions between the coordinated NO₃⁻ anions and the imide ring of DPNDI; while 2 is a two-dimensional network with a (4, 4) net topology. In the case of 3, due to the presence of uncoordinated perchlorate counter ions, it exhibits a non-interpenetrated square-grid coordination polymer containing one-dimensional rhomboid channels. The structural diversity in these compounds is attributed to different coordination abilities and geometries of counter anions. Due to the presence of electron-deficient NDI moiety, the photochromic behavior of these compounds was studied. Interestingly, only compounds 1 and 3 exhibit color changes under light irradiation. The influence of the anions on the photochromism process of the NDI-based materials has been discussed. Full article

(This article belongs to the Special Issue Coordination Polymer)

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14 pages, 3678 KiB

Open AccessArticle

Effect of WS₂ Inorganic Nanotubes on Isothermal Crystallization Behavior and Kinetics of Poly(3-Hydroxybutyrate-co-3-hydroxyvalerate)

by Tyler Silverman¹, Mohammed Naffakh^1,*

, Carlos Marco² and Gary Ellis²

¹ Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid (ETSII-UPM), José Gutiérrez Abascal 2, 28006 Madrid, Spain

² Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain

Polymers 2018, 10(2), 166; https://doi.org/10.3390/polym10020166 - 9 Feb 2018

Cited by 9 | Viewed by 4986

Abstract

Nanocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and tungsten disulfide inorganic nanotubes (INT-WS₂) were prepared by blending in solution, and the effects of INT-WS₂ on the isothermal crystallization behavior and kinetics of PHBV were investigated for the first time. The isothermal [...] Read more.

Nanocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and tungsten disulfide inorganic nanotubes (INT-WS₂) were prepared by blending in solution, and the effects of INT-WS₂ on the isothermal crystallization behavior and kinetics of PHBV were investigated for the first time. The isothermal crystallization process was studied in detail using various techniques, with emphasis on the role of INT-WS₂ concentration. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) showed that, in the nucleation-controlled regime, crystallization rates of PHBV in the nanocomposites are influenced by the INT-WS₂ loading. Our results demonstrated that low loadings of INT-WS₂ (0.1–1.0 wt %) increased the crystallization rates of PHBV, reducing the fold surface free energy by up to 24%. This is ascribed to the high nucleation efficiency of INT-WS₂ on the crystallization of PHBV. These observations facilitate a deeper understanding of the structure-property relationships in PHBV biopolymer nanocomposites and are useful for their practical applications. Full article

(This article belongs to the Special Issue Nanoparticle-Reinforced Polymers)

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14 pages, 3708 KiB

Open AccessArticle

Poly(butylene 2,5-thiophenedicarboxylate): An Added Value to the Class of High Gas Barrier Biopolyesters

by Giulia Guidotti¹, Matteo Gigli^2,*

, Michelina Soccio¹, Nadia Lotti^1,*

, Massimo Gazzano³, Valentina Siracusa⁴

and Andrea Munari¹

¹ Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Via Terracini 28, 40131 Bologna, Italy

² Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy

³ Organic Synthesis and Photoreactivity Institute, CNR, Via Gobetti 101, 40129 Bologna, Italy

⁴ Department of Chemical Science, University of Catania, Viale A. Doria 6, 95125 Catania, Italy

Polymers 2018, 10(2), 167; https://doi.org/10.3390/polym10020167 - 9 Feb 2018

Cited by 48 | Viewed by 4962

Abstract

Many efforts are currently devoted to the design and development of high performance bioplastics to replace traditional fossil-based polymers. In response, this contribution presents a new biobased aromatic polyester, i.e., poly(butylene 2,5-thiophenedicarboxylate) (PBTF). Here, PBTF is characterized from the molecular, thermo-mechanical and structural [...] Read more.

Many efforts are currently devoted to the design and development of high performance bioplastics to replace traditional fossil-based polymers. In response, this contribution presents a new biobased aromatic polyester, i.e., poly(butylene 2,5-thiophenedicarboxylate) (PBTF). Here, PBTF is characterized from the molecular, thermo-mechanical and structural point of view. Gas permeability is evaluated at different temperatures, in the range below and above glass transition, providing a full insight into the performances of this material under different operating conditions, and demonstrating the superior gas barrier behavior of PBTF with respect to other polyesters, such as PEF and PET. The combination of calorimetric and diffractometric studies allows for a deep understanding of the structure of PBTF, revealing the presence of a not-induced 2D-ordered phase (meso-phase), responsible for its outstanding gas permeability behavior. The simple synthetic strategy adopted, the exceptional barrier properties, combined with the interesting mechanical characteristics of PBTF open up new scenarios in the world of green and sustainable packaging materials. Full article

(This article belongs to the Special Issue Polymers for Packaging Applications)

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14 pages, 4022 KiB

Open AccessArticle

Crystallization Kinetics of Polyamide 12 during Selective Laser Sintering

by Meng Zhao, Katrin Wudy and Dietmar Drummer^*

Institute of Polymer Technology (LKT), Friedrich-Alexander-University Erlangen-Nuremberg, 91054 Erlangen, Germany

Polymers 2018, 10(2), 168; https://doi.org/10.3390/polym10020168 - 9 Feb 2018

Cited by 86 | Viewed by 8279

Abstract

Selective laser sintering (SLS) of thermoplastic materials is an additive manufacturing process that overcomes the boundary between prototype construction and functional components. This technique also meets the requirements of traditional and established production processes. Crystallization behavior is one of the most critical properties [...] Read more.

Selective laser sintering (SLS) of thermoplastic materials is an additive manufacturing process that overcomes the boundary between prototype construction and functional components. This technique also meets the requirements of traditional and established production processes. Crystallization behavior is one of the most critical properties during the cooling process and needs to be fully understood. Due to the huge influence of crystallization on the mechanical and thermal properties, it is important to investigate this process more closely. A commercial SLS polyamide (PA12) powder was measured with differential scanning calorimetry (DSC) to model a wider temperature range. To model isothermal crystallization between 160 and 168 °C, the Avrami model was used to determine the degree of crystallization. For non-isothermal crystallization between 0.2 and 20 K/min, different models were compared including the Ozawa, Jeziory, and Nakamura equations. Full article

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14 pages, 19483 KiB

Open AccessArticle

Fatigue and Durability of Laminated Carbon Fibre Reinforced Polymer Straps for Bridge Suspenders

by Fabio Baschnagel¹, Rea Härdi^1,2, Zafiris Triantafyllidis³, Urs Meier⁴ and Giovanni Pietro Terrasi^1,3,*

¹ Mechanical Systems Engineering Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland

² Department of Materials, ETH Zuerich, 8093 Zuerich, Switzerland

³ Institute for Infrastructure and Environment, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FG, UK

⁴ Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland

Polymers 2018, 10(2), 169; https://doi.org/10.3390/polym10020169 - 10 Feb 2018

Cited by 21 | Viewed by 6859

Abstract

Steel cables and suspenders in bridges are at high risk of corrosion-fatigue and in some cases of fretting-fatigue in their anchorages. These factors greatly limit the service stresses of a specific cable system and involve expensive protection measures. In order to investigate the [...] Read more.

Steel cables and suspenders in bridges are at high risk of corrosion-fatigue and in some cases of fretting-fatigue in their anchorages. These factors greatly limit the service stresses of a specific cable system and involve expensive protection measures. In order to investigate the above limitations, the fretting fatigue behaviour of pin-loaded carbon fibre reinforced polymer (CFRP) straps was studied as models for corrosion-resistant bridge suspenders. Two types of straps were tested: small model straps with a sacrificial CFRP ply and large full-scale straps. In a first phase, five fully laminated and carbon pin-loaded CFRP model straps were subjected to an ultimate tensile strength test. Thereafter, and in order to assess their durability, 20 model straps were subjected to a fretting fatigue test, which was successfully passed by 4 straps. An S-N curve was generated for a load ratio of 0.1 and a frequency of 10 Hz. In a second phase, one full-scale strap was tested for its ultimate tensile strength and two full-scale straps were fatigue-tested. The influence of fretting fatigue loading on the residual mechanical properties of the straps was also assessed, and although fretting fatigue represented an important limitation for laminated CFRP straps, it could be shown that the investigated CFRP tension members can compete with the well-established steel suspenders. Full article

(This article belongs to the Special Issue Selected Papers from "SMAR 2017")

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14 pages, 7479 KiB

Open AccessArticle

Preparation of Protein Molecular-Imprinted Polysiloxane Membrane Using Calcium Alginate Film as Matrix and Its Application for Cell Culture

by Dong Liu¹, Kongyin Zhao^1,2,*

, Meng Qi², Shuwen Li², Guoqing Xu², Junfu Wei^1,2 and Xiaoling He²

¹ State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387, China

² School of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China

Polymers 2018, 10(2), 170; https://doi.org/10.3390/polym10020170 - 10 Feb 2018

Cited by 27 | Viewed by 5475

Abstract

Bovine serum albumin (BSA) molecular-imprinted polysiloxane (MIP) membrane was prepared by sol-gel technology, using silanes as the functional monomers, BSA as the template and CaAlg hydrogel film as the matrix. The stress-strain curves of wet CaAlg membrane and molecular-imprinted polysiloxane membrane were investigated. [...] Read more.

Bovine serum albumin (BSA) molecular-imprinted polysiloxane (MIP) membrane was prepared by sol-gel technology, using silanes as the functional monomers, BSA as the template and CaAlg hydrogel film as the matrix. The stress-strain curves of wet CaAlg membrane and molecular-imprinted polysiloxane membrane were investigated. We evaluate the adsorption and recognition properties of MIP membrane. Results showed that the adsorption capacity of BSA-imprinted polysiloxane for BSA reached 28.83 mg/g, which was 2.18 times the non-imprinted polysiloxane (NIP) membrane. The adsorption rate was higher than that of the protein-imprinted hydrogel. BSA-imprinted polysiloxane membrane could identify the protein template from competitive proteins such as bovine hemoglobin, ovalbumin and bovine γ-globulin. In order to obtain the biomaterial that can promote cell adhesion and proliferation, fibronectin (FN)-imprinted polysiloxane (FN-MIP) membrane was obtained by using fibronectin as the template, silanes as functional monomers, and CaAlg hydrogel membrane as the substrate or matrix. The FN-MIP adsorbed more FN than NIP. The FN-imprinted polysiloxane membrane was applied to culture mouse fibroblast cells (L929) and the results proved that the FN-MIP had a better effect on cell adhesion than NIP. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers)

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11 pages, 1661 KiB

Open AccessArticle

Hyperbranched Glycopolymers of 2-(α-d-Mannopyranose) Ethyl Methacrylate and N,N’-Methylenebisacrylamide: Synthesis, Characterization and Multivalent Recognitions with Concanavalin A

by Yuangong Zhang¹, Bo Wang², Ye Zhang¹, Ying Zheng¹, Xin Wen^1,*, Libin Bai^1,2 and Yonggang Wu^1,*

¹ College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China

² College of Chemical Engineering and Materials, Handan University, Handan 056005, China

Polymers 2018, 10(2), 171; https://doi.org/10.3390/polym10020171 - 10 Feb 2018

Cited by 7 | Viewed by 4963

Abstract

A series of novel hyperbranched poly[2-(α-d-mannopyranosyloxy) ethyl methacrylate-co-N,N’-methylenebisacrylamide] (HPManEMA-co-MBA) are synthesized via a reversible addition fragmentation polymerization (RAFT). The dosage ratios of linear and branch units are tuned to obtain different degree of [...] Read more.

A series of novel hyperbranched poly[2-(α-d-mannopyranosyloxy) ethyl methacrylate-co-N,N’-methylenebisacrylamide] (HPManEMA-co-MBA) are synthesized via a reversible addition fragmentation polymerization (RAFT). The dosage ratios of linear and branch units are tuned to obtain different degree of branching (DB) in hyperbranched glycopolymers. The DB values are calculated according to the content of nitrogen, which are facilely determined by elemental analysis. The lectin-binding properties of HPManEMA-co-MBA to concanavalin A (ConA) are examined using a turbidimetric assay. The influence of defined DB value and molecular weight of HPManEMA-co-MBA on the clustering rate is studied. Notably, HPManEMA-co-MBAs display a low cytotoxicity in the MTT assay, thus are potential candidates for biomedical applications. Full article

(This article belongs to the Special Issue Hydrophilic Polymers)

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12 pages, 4391 KiB

Open AccessArticle

Microencapsulated Comb-Like Polymeric Solid-Solid Phase Change Materials via In-Situ Polymerization

by Wei Li^*

, Xiaoye Geng, Rui Huang, Jianping Wang, Ning Wang and Xingxiang Zhang

State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Key Laboratory of Advanced Fibers and Energy Storage, School of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China

Polymers 2018, 10(2), 172; https://doi.org/10.3390/polym10020172 - 11 Feb 2018

Cited by 18 | Viewed by 6324

Abstract

To enhance the thermal stability and permeability resistance, a comb-like polymer with crystallizable side chains was fabricated as solid-solid phase change materials (PCMs) inside the cores of microcapsules and nanocapsules prepared via in-situ polymerization. In this study, the effects on the surface morphology [...] Read more.

To enhance the thermal stability and permeability resistance, a comb-like polymer with crystallizable side chains was fabricated as solid-solid phase change materials (PCMs) inside the cores of microcapsules and nanocapsules prepared via in-situ polymerization. In this study, the effects on the surface morphology and microstructure of micro/nanocapsules caused by microencapsulating different types of core materials (i.e., n-hexadecane, ethyl hexadecanoate, hexadecyl acrylate and poly(hexadecyl acrylate)) were systematically studied via field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The confined crystallization behavior of comb-like polymer PCMs cores was investigated via differential scanning calorimeter (DSC). Comparing with low molecular organic PCMs cores, the thermal stability of PCMs microencapsulated comb-like polymer enhanced significantly, and the permeability resistance improved obviously as well. Based on these resultant analysis, the microencapsulated comb-like polymeric PCMs with excellent thermal stability and permeability resistance showed promising foreground in the field of organic solution spun, melt processing and organic coating. Full article

(This article belongs to the Special Issue Tailored Polymer Synthesis by Advanced Polymerization Techniques)

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10 pages, 9142 KiB

Open AccessArticle

Study about Mechanical Property and Machinability of Polyimide

by Shijun Ji¹, Jilong Yang¹, Ji Zhao¹, Yanjuan Hu^2,3,* and Hong Gao^1,*

¹ School of Mechanical Science and Engineering, Jilin University, Changchun 130025, China

² College of Biological and Agricultural Engineering, Jilin University, Changchun 130025, China

³ School of Mechanical and Electrical Engineering, Changchun University of Technology, Changchun 130012, China

Polymers 2018, 10(2), 173; https://doi.org/10.3390/polym10020173 - 11 Feb 2018

Cited by 22 | Viewed by 5561

Abstract

Polyimide (PI) is a kind of polymer material with properties of high heat-resistance and good mechanical strength. As a special engineering material, it has been widely used in the fields of aviation, nanotechnology, etc. PI has been regarded as one of the most [...] Read more.

Polyimide (PI) is a kind of polymer material with properties of high heat-resistance and good mechanical strength. As a special engineering material, it has been widely used in the fields of aviation, nanotechnology, etc. PI has been regarded as one of the most promising engineering plastics in the future. Therefore, further research must be made on its mechanical properties and machinability of the PI, especially in ultra-precision machining. In this paper, both of the mechanical properties and machinability have been studied respectively. Through the nanoindentation experiment, the nanoindentation hardness and elastic modulus of PI are analyzed. Also, the single point diamond turning (SPDT) experiment is conducted to show that the form accuracy and surface roughness of PI surface can reach a submicron degree in peak-to-valley (PV) and a nanometer scale in surface roughness (Ra) respectively. The results demonstrate that the PI possesses good mechanical properties and machinability. Full article

(This article belongs to the Special Issue Mechanics of Emerging Polymers with Unprecedented Networks)

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14 pages, 2755 KiB

Open AccessArticle

Optimizing Circulating Tumor Cells’ Capture Efficiency of Magnetic Nanogels by Transferrin Decoration

by Catalina Biglione^1,2,†, Julian Bergueiro^2,†

, Mazdak Asadian-Birjand², Christoph Weise², Vrushali Khobragade^3,4, Govind Chate⁵, Manoj Dongare^3,4,5, Jayant Khandare^3,4,5, Miriam C. Strumia¹

and Marcelo Calderón^2,*

¹ LAMAP Laboratorio de Materiales Poliméricos, IPQA-CONICET, Departamento de Química, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, X5000HUA Córdoba, Argentina

² Freie Universität Berlin, Institute of Chemistry and Biochemistry, Takustr. 3, 14195 Berlin, Germany

³ Actorius Innovations and Research, B 411, GO Square, Wakad Road, 411057 Pune, India

⁴ Surgical Oncologist, Manik Hospital and Research Center, Aurangabad 431001, India

⁵ MAEER’s Maharashtra Institute of Pharmacy, Kothrud, Pune 411038, Maharashtra, India

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 174; https://doi.org/10.3390/polym10020174 - 11 Feb 2018

Cited by 15 | Viewed by 6664

Abstract

Magnetic nanogels (MNGs) are designed to have all the required features for their use as highly efficient trapping materials in the challenging task of selectively capturing circulating tumor cells (CTCs) from the bloodstream. Advantageously, the discrimination of CTCs from hematological cells, which is [...] Read more.

Magnetic nanogels (MNGs) are designed to have all the required features for their use as highly efficient trapping materials in the challenging task of selectively capturing circulating tumor cells (CTCs) from the bloodstream. Advantageously, the discrimination of CTCs from hematological cells, which is a key factor in the capturing process, can be optimized by finely tuning the polymers used to link the targeting moiety to the MNG. We describe herein the relationship between the capturing efficiency of CTCs with overexpressed transferrin receptors and the different strategies on the polymer used as linker to decorate these MNGs with transferrin (Tf). Heterobifunctional polyethylene glycol (PEG) linkers with different molecular weights were coupled to Tf in different ratios. Optimal values over 80% CTC capture efficiency were obtained when 3 PEG linkers with a length of 8 ethylene glycol (EG) units were used, which reveals the important role of the linker in the design of a CTC-sorting system. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Biointerface)

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13 pages, 1408 KiB

Open AccessArticle

Formulation of Carbopol^®/Poly(2-ethyl-2-oxazoline)s Mucoadhesive Tablets for Buccal Delivery of Hydrocortisone

by Leire Ruiz-Rubio^1,*

, María Luz Alonso²

, Leyre Pérez-Álvarez¹, Rosa Maria Alonso², Jose Luis Vilas¹

and Vitaliy V. Khutoryanskiy^3,*

¹ Macromolecular Chemistry Group (LABQUIMAC), Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country, UPV/EHU, Barrio Sarriena, s/n, 48940 Leioa, Spain

² Analytical Chemistry Department, Faculty of Science and Technology, University of the Basque Country, UPV/EHU, Barrio Sarriena, s/n, 48940 Leioa, Spain

³ School of Pharmacy, University of Reading, Whiteknights, P.O. Box 224, Reading RG6 6AD, UK

Polymers 2018, 10(2), 175; https://doi.org/10.3390/polym10020175 - 11 Feb 2018

Cited by 37 | Viewed by 8536

Abstract

Poly(2-ethyl-2-oxazoline) has become an excellent alternative to the use of poly(ethylene glycol) in pharmaceutical formulations due to its valuable physicochemical and biological properties. This work presents a formulation of poorly-water soluble drug, hydrocortisone, using interpolymer complexes and physical blends of poly(2-ethyl-2-oxazoline)s and two [...] Read more.

Poly(2-ethyl-2-oxazoline) has become an excellent alternative to the use of poly(ethylene glycol) in pharmaceutical formulations due to its valuable physicochemical and biological properties. This work presents a formulation of poorly-water soluble drug, hydrocortisone, using interpolymer complexes and physical blends of poly(2-ethyl-2-oxazoline)s and two Carbopols^® (Carbopol 974 and Carbopol 971) for oromucosal administration. The swelling, hydrocortisone release and mucoadhesive properties of a series of tablet formulations obtained by combination of different Carbopols with poly(2-ethyl-2-oxazoline)s of different molecular weights have been evaluated in vitro. Full article

(This article belongs to the Special Issue Advances in Mucoadhesive Polymers and Formulations for Transmucosal Drug Delivery)

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16 pages, 14587 KiB

Open AccessArticle

Functionalization of Graphene Oxide with Low Molecular Weight Poly (Lactic Acid)

by Mingwei Yuan^1,2, Yike Chen³, Minglong Yuan³

, Hongli Li³, Xiansong Xia^1,2 and Chengdong Xiong^1,*

¹ Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China

² University of Chinese Academy of Sciences, Beijing 100049, China

³ Engineering Research Center of Biopolymer Functional Materials of Yunnan, Yunnan Minzu University, Kunming 650500, China

Polymers 2018, 10(2), 177; https://doi.org/10.3390/polym10020177 - 12 Feb 2018

Cited by 17 | Viewed by 5212

Abstract

In this paper, the hydroxyl groups on the surface of graphene oxide (GO) were used to initiate the ring-opening polymerization of a lactic acid O-carboxyanhydride. GO grafted with poly (l-lactic acid) molecular chains (GO-g-PLLA) was prepared. Lactic acid [...] Read more.

In this paper, the hydroxyl groups on the surface of graphene oxide (GO) were used to initiate the ring-opening polymerization of a lactic acid O-carboxyanhydride. GO grafted with poly (l-lactic acid) molecular chains (GO-g-PLLA) was prepared. Lactic acid O-carboxyanhydride has a higher polymerization activity under mild polymerization conditions. Thus, the functionalization of the polymer chains and obtaining poly (lactic acid) (PLLA) was easily achieved by ring-opening polymerization with 4-dimethylaminopyridine (DMAP) as the catalyst. The results showed that with this method, PLLA can be rapidly grafted to the surface of GO in one step. As a result, the chemical structure of the GO surface was altered, improving its dispersion in organic solvents and in a PLLA matrix, as well as its bonding strength with the PLLA interface. We then prepared GO/PLLA and PLLA/GO-g-PLLA composite materials and investigated the differences in their interfacial properties and mechanical properties. GO-g-PLLA exhibited excellent dispersion in the PLLA matrix and formed excellent interfacial bonds with PLLA through mechanical interlocking, demonstrating a significant enhancement effect compared to PLLA. The water vapor and oxygen permeabilities of the GO-g-PLLA/PLLA composite decreased by 19% and 29%, respectively. Full article

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19 pages, 1831 KiB

Open AccessArticle

Biocompatible Porous Polyester-Ether Hydrogel Scaffolds with Cross-Linker Mediated Biodegradation and Mechanical Properties for Tissue Augmentation

by Berkay Ozcelik¹, Jason Palmer², Katharina Ladewig¹, Paula Facal Marina^3,4

, Geoffrey W. Stevens¹

, Keren Abberton^2,†, Wayne A. Morrison^2,‡, Anton Blencowe^3,4,*

and Greg G. Qiao^1,*

¹ Department of Chemical & Biomolecular Engineering, The University of Melbourne, Parkville, Melbourne, VIC 3010, Australia

² O’Brien Institute Department, St. Vincent’s Institute of Medical Research, Melbourne, VIC 3065, Australia

³ School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia

⁴ Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia

^† Current addresses: Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, Victoria 3052 Australia; The University of Melbourne, Department of Pediatrics, The Royal Children’s Hospital, Parkville, Victoria 3052 Australia.

^‡ Current addresses: Department of Surgery, St Vincent’s Hospital, The University of Melbourne, Parkville, Melbourne, Victoria 3010, Australia; Faculty Health Sciences, Australian Catholic University, Fitzroy, Melbourne, Victoria 3065, Australia.

Polymers 2018, 10(2), 179; https://doi.org/10.3390/polym10020179 - 12 Feb 2018

Cited by 8 | Viewed by 5218

Abstract

Porous polyester-ether hydrogel scaffolds (PEHs) were fabricated using acid chloride/alcohol chemistry and a salt templating approach. The PEHs were produced from readily available and cheap commercial reagents via the reaction of hydroxyl terminated poly(ethylene glycol) (PEG) derivatives with sebacoyl, succinyl, or trimesoyl chloride [...] Read more.

Porous polyester-ether hydrogel scaffolds (PEHs) were fabricated using acid chloride/alcohol chemistry and a salt templating approach. The PEHs were produced from readily available and cheap commercial reagents via the reaction of hydroxyl terminated poly(ethylene glycol) (PEG) derivatives with sebacoyl, succinyl, or trimesoyl chloride to afford ester cross-links between the PEG chains. Through variation of the acid chloride cross-linkers used in the synthesis and the incorporation of a hydrophobic modifier (poly(caprolactone) (PCL)), it was possible to tune the degradation rates and mechanical properties of the resulting hydrogels. Several of the hydrogel formulations displayed exceptional mechanical properties, remaining elastic without fracture at compressive strains of up to 80%, whilst still displaying degradation over a period of weeks to months. A subcutaneous rat model was used to study the scaffolds in vivo and revealed that the PEHs were infiltrated with well vascularised tissue within two weeks and had undergone significant degradation in 16 weeks without any signs of toxicity. Histological evaluation for immune responses revealed that the PEHs incite only a minor inflammatory response that is reduced over 16 weeks with no evidence of adverse effects. Full article

(This article belongs to the Special Issue Hydrogels in Tissue Engineering and Regenerative Medicine)

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9 pages, 1793 KiB

Open AccessArticle

Elucidation of Spatial Distribution of Hydrophobic Aromatic Compounds Encapsulated in Polymer Micelles by Anomalous Small-Angle X-ray Scattering

by Shota Sasaki, Ginpei Machida, Ryosuke Nakanishi, Masaki Kinoshita and Isamu Akiba^*

Department of Chemistry and Biochemistry, The University of Kitakyushu, 1-1 Hibikino, Wakamatsu, Kitakyushu 8080135, Japan

Polymers 2018, 10(2), 180; https://doi.org/10.3390/polym10020180 - 12 Feb 2018

Cited by 7 | Viewed by 4548

Abstract

Spatial distribution of bromobenzene (BrBz) and 4-bromophenol (BrPh) as hydrophobic aromatic compounds incorporated in polymer micelles with vesicular structure consisting of poly(ethylene glycol)-b-poly(tert-butyl methacrylate) (PEG-b-PtBMA) in aqueous solution is investigated by anomalous small-angle X-ray scattering (ASAXS) analyses [...] Read more.

Spatial distribution of bromobenzene (BrBz) and 4-bromophenol (BrPh) as hydrophobic aromatic compounds incorporated in polymer micelles with vesicular structure consisting of poly(ethylene glycol)-b-poly(tert-butyl methacrylate) (PEG-b-PtBMA) in aqueous solution is investigated by anomalous small-angle X-ray scattering (ASAXS) analyses near Br K edge. Small-angle X-ray scattering (SAXS) intensities from PEG-b-PtBMA micelles containing BrBz and BrPh were decreased as the energy of incident X-ray approached to Br K edge corresponding to the energy dependence of anomalous scattering factor of Br. The analysis for the energy dependence of SAXS profiles from the PEG-b-PtBMA micelles containing BrBz revealed that BrBz molecules were located in hydrophobic layer of PEG-b-PtBMA micelles. On the contrary, it was found by ASAXS that BrPh existed not only in the hydrophobic layer but also in the shell layer. Since ASAXS analysis successfully accomplished to visualize the spatial distribution of hydrophobic molecules in polymer micelles, it should be expected to be a powerful tool for characterization of drug delivery vehicles. Full article

(This article belongs to the Special Issue Polymer Micelles)

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14 pages, 2493 KiB

Open AccessArticle

Polycomplexes of Hyaluronic Acid and Borates in a Solid State and Solution: Synthesis, Characterization and Perspectives of Application in Boron Neutron Capture Therapy

by Alexander N. Zelenetskii^1,2,*, Sergey Uspenskii^1,2, Alexander Zaboronok^3,*

, Georgij Cherkaev^1,2, Alexander Shchegolihin⁴, Bryan J. Mathis³

, Mikhail Selyanin¹, Tetsuya Yamamoto⁵ and Akira Matsumura³

¹ R&D Center “Suisselle,” CEI3, rue Galilée 6, 1400 Yverdon-les-Bains, Switzerland

² Institute of Synthetic Polymer Materials, Russian Academy of Sciences, Profsoyuznaya st. 70, 117393 Moscow, Russian

³ Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan

⁴ Institute for Biochemical Physics, Russian Academy of Sciences, Kosygina st. 4, 119334 Moscow, Russian

⁵ Department of Neurosurgery, Graduate School of Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa, Yokohama 236-0004, Japan

Polymers 2018, 10(2), 181; https://doi.org/10.3390/polym10020181 - 13 Feb 2018

Cited by 15 | Viewed by 6340

Abstract

In this report, we propose a new polyborate fragment synthesis strategy along the whole chain of the polysaccharide hyaluronic acid (HA) to produce boron neutron capture therapy (BNCT) compounds. Under high pressure and deformatory solid-state conditions, polymolecular system formation takes place due to [...] Read more.

In this report, we propose a new polyborate fragment synthesis strategy along the whole chain of the polysaccharide hyaluronic acid (HA) to produce boron neutron capture therapy (BNCT) compounds. Under high pressure and deformatory solid-state conditions, polymolecular system formation takes place due to association of phase-specific transition components into a more or less distinct microscopic organization. Fourier transform infrared (FTIR) spectroscopy shows that HA and polyborates form a network of cyclic polychelate complexes. HA acts as a multidentate ligand using carboxylic and hydroxyl proton donor groups to link oxygen atoms in B–O–B bonds and borate-anions B–O(−): O–H···O, O–H···(−)O. With free electron pairs in heteroatoms –O(:)···B, –N(:)···B, HA can act simultaneously as an electron donor. Nuclear magnetic resonance (NMR) with ¹³C and ¹H reveals a preserved complex interaction after both solubilizing and attenuating the HA-polyborate system. Stability of the product in water, low cost, ease of synthesis and scalability of manufacturing indicate that HA-polyborate complexes might have advantages over current chemotherapeutic approaches in creating therapeutic agents for BNCT. Full article

(This article belongs to the Special Issue Polymer Hybrid Materials)

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14 pages, 8091 KiB

Open AccessArticle

Coordination Polymers Based on Phthalic Acid and Aminopyrazine Ligands: On the Importance of N–H···π Interactions

by Anowar Hossain¹, Saikat Kumar Seth^2,*

, Antonio Bauzá³

, Subrata Mukhopadhyay¹ and Antonio Frontera^3,*

¹ Department of Chemistry, Jadavpur University, Kolkata 700032, India

² Department of Physics, Jadavpur University, Kolkata 700032, India

³ Department of Chemistry, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain

Polymers 2018, 10(2), 182; https://doi.org/10.3390/polym10020182 - 13 Feb 2018

Cited by 19 | Viewed by 4832

Abstract

Two new Co(II) and Cu(II) coordination polymers, {Co(HL₁)₂(μ-L₂)(H₂O)₂}_n (1) and {[Cu(HL₁)₂(μ-L₂)H₂O]·H₂O}_n (2) (H₂L₁ = [...] Read more.

Two new Co(II) and Cu(II) coordination polymers, {Co(HL₁)₂(μ-L₂)(H₂O)₂}_n (1) and {[Cu(HL₁)₂(μ-L₂)H₂O]·H₂O}_n (2) (H₂L₁ = Phthalic acid and L₂ = 2-aminopyrazine), have been synthesized by slow evaporation of solvent and characterized by IR spectroscopic, elemental, single-crystal X-ray diffraction and thermal analysis. X-ray results indicate that in both the polymers, phthalate acts as a monodentate ligand and the aminopyrazine ligand is responsible for the formation of the infinite one-dimensional chain structure. The solid-state structures are stabilized through hydrogen bonds and N‒H···π interactions by generating two-dimensional layered structures. Finally, the non-covalent interactions have been studied energetically and using Bader’s theory of atoms in molecules by means of Density Functional Theory (DFT) calculations. The influence of the metal coordination on the strength of the interaction has been studied using molecular electrostatic potential surface calculations. Full article

(This article belongs to the Special Issue Coordination Polymer)

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10 pages, 8153 KiB

Open AccessCommunication

Carbon-Based Nanomaterials from Biopolymer Lignin via Catalytic Thermal Treatment at 700 to 1000 °C

by Xuefeng Zhang¹

, Qiangu Yan², Jinghao Li², I-Wei Chu³, Hossein Toghiani⁴, Zhiyong Cai^2,* and Jilei Zhang^1,*

¹ Department of Sustainable Bioproducts, Mississippi State University, Mississippi State, MS 39762, USA

² U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI 53726, USA

³ Institute of Imaging and Analytical Technology, Mississippi State University, Mississippi State, MS 39762, USA

⁴ Dave C. Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762, USA

Polymers 2018, 10(2), 183; https://doi.org/10.3390/polym10020183 - 13 Feb 2018

Cited by 31 | Viewed by 4893

Abstract

We report the preparation of carbon-based nanomaterials from biopolymer kraft lignin via an iron catalytic thermal treatment process. Both the carbonaceous gases and amorphous carbon (AC) from lignin thermal decomposition were found to have participated in the formation of graphitic-carbon-encapsulated iron nanoparticles (GCEINs). [...] Read more.

We report the preparation of carbon-based nanomaterials from biopolymer kraft lignin via an iron catalytic thermal treatment process. Both the carbonaceous gases and amorphous carbon (AC) from lignin thermal decomposition were found to have participated in the formation of graphitic-carbon-encapsulated iron nanoparticles (GCEINs). GCEINs originating from carbonaceous gases have thick-walled graphitic-carbon layers (10 to 50) and form at a temperature of 700 °C. By contrast, GCEINs from AC usually have thin-walled graphitic-carbon layers (1 to 3) and form at a temperature of at least 800 °C. Iron catalyst nanoparticles started their phase transition from α-Fe to γ-Fe at 700 °C, and then from γ-Fe to Fe₃C at 1000 °C. Furthermore, we derived a formula to calculate the maximum number of graphitic-carbon layers formed on iron nanoparticles via the AC dissolution-precipitation mechanism. Full article

(This article belongs to the Special Issue Lignin Polymers: Structures, Reactions and Applications)

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16 pages, 5041 KiB

Open AccessArticle

Microencapsulation of Phosphorylated Human-Like Collagen-Calcium Chelates for Controlled Delivery and Improved Bioavailability

by Yu Mi^1,2, Zhengfang Liu^1,2, Jianjun Deng^1,2, Huan Lei^1,2, Chenhui Zhu^1,2,*, Daidi Fan^1,2,* and Xingqiang Lv^1,2

¹ Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering, Northwest University, 229 North Taibai Road, Xi’an 710069, Shaanxi, China

² Shaanxi R&D Center of Biomaterials and Fermentation Engineering, School of Chemical Engineering, Northwest University, 229 North Taibai Road, Xi’an 710069, Shaanxi, China

Polymers 2018, 10(2), 185; https://doi.org/10.3390/polym10020185 - 14 Feb 2018

Cited by 12 | Viewed by 4382

Abstract

The bioavailability of Phosphorylated Human-like Collagen-calcium chelates (PHLC-Ca) as calcium supplement is influenced by the extremely low pH and proteolytic enzymes in the gastrointestinal tract. This study addresses these issues by microencapsulation technology using alginate (ALG) and chitosan (CS) as wall materials. The [...] Read more.

The bioavailability of Phosphorylated Human-like Collagen-calcium chelates (PHLC-Ca) as calcium supplement is influenced by the extremely low pH and proteolytic enzymes in the gastrointestinal tract. This study addresses these issues by microencapsulation technology using alginate (ALG) and chitosan (CS) as wall materials. The different ratio of ALG to PHLC-Ca on microcapsules encapsulation efficiency (EE) and loading capacity (LC) was evaluated and 1:1/2 was selected as the optimal proportion. The microcapsules were micron-sized and spherical in shape. PHLC-Ca was successfully entrapped into the matrix of ALG through forming intermolecular hydrogen bonding or other interactions. The confocal laser scanning microscopy (CLSM) indicated that CS was coated on ALG microspheres. The MTT assay exhibited that CS/ALG-(PHLC-Ca) microcapsules extracts were safe to L929. The animal experiment showed that CS/ALG-(PHLC-Ca) microcapsules was superior to treating osteoporosis than PHLC-Ca. These results illustrated that the bioavailability of PHLC-Ca was improved by microencapsulated. Full article

(This article belongs to the Special Issue Polymers for Therapy and Diagnostics)

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16 pages, 3134 KiB

Open AccessArticle

Rheological Behavior of Amino-Functionalized Multi-Walled Carbon Nanotube/Polyacrylonitrile Concentrated Solutions and Crystal Structure of Composite Fibers

by Hailong Zhang^1,2,*

, Ling Quan³, Fengjun Shi¹, Changqing Li², Huanqiang Liu¹ and Lianghua Xu²

¹ School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450045, China

² Key Laboratory of Carbon Fiber and Functional Polymers Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China

³ School of Electric Power, North China University of Water Resources and Electric Power, Zhengzhou 450045, China

Polymers 2018, 10(2), 186; https://doi.org/10.3390/polym10020186 - 14 Feb 2018

Cited by 30 | Viewed by 6669

Abstract

The rheological behavior of amino-functionalized multi-walled carbon nanotubes (amino-CNTs)/polyacrylonitrile (PAN) concentrated solutions in the dimethyl sulphoxide solvent and the effects of the amino-CNTs on the PAN precursor fibers by wet-spinning method were investigated. The amino-CNT/PAN concentrated solutions prepared by in situ solution polymerization [...] Read more.

The rheological behavior of amino-functionalized multi-walled carbon nanotubes (amino-CNTs)/polyacrylonitrile (PAN) concentrated solutions in the dimethyl sulphoxide solvent and the effects of the amino-CNTs on the PAN precursor fibers by wet-spinning method were investigated. The amino-CNT/PAN concentrated solutions prepared by in situ solution polymerization with homogeneous dispersion of amino-CNTs have higher complex viscosity, storage modulus and loss modulus as compared to the control PAN concentrated solutions containing 22% PAN polymer by mass. The composite fibers with amino-CNTs of 1 wt % have lower degree of crystallization, crystal size and crystal region orientation compared to the control PAN precursor fibers. However, the amino-CNT/PAN composite fibers with diameter of about 10.5 μm exhibit higher mechanical properties than the control PAN precursor fibers with diameter of about 8.0 μm. Differential scanning calorimetry analysis demonstrated that the cyclization reaction in composite fibers have broad exothermic temperature range and low exothermic rate. These results indicate that the addition of amino-CNTs into PAN precursor fibers is beneficial to controlling the process of thermal stabilization and obtaining the higher performance of composite fibers. Full article

(This article belongs to the Special Issue Mechanics of Emerging Polymers with Unprecedented Networks)

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11 pages, 4624 KiB

Open AccessArticle

Conjugate of PAMAM Dendrimer, Doxorubicin and Monoclonal Antibody—Trastuzumab: The New Approach of a Well-Known Strategy

by Monika Marcinkowska¹, Ewelina Sobierajska¹, Maciej Stanczyk², Anna Janaszewska¹, Arkadiusz Chworos³

and Barbara Klajnert-Maculewicz^1,4,*

¹ Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland

² Department of Surgical Oncology, Cancer Center, Copernicus Memorial Hospital, 93-509 Lodz, Poland

³ Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-236 Lodz, Poland

⁴ Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, 01069 Dresden, Germany

Polymers 2018, 10(2), 187; https://doi.org/10.3390/polym10020187 - 14 Feb 2018

Cited by 52 | Viewed by 7118

Abstract

The strategy utilizing trastuzumab, a humanized monoclonal antibody against human epidermal growth receptor 2 (HER-2), as a therapeutic agent in HER-2 positive breast cancer therapy seems to have advantage over traditional chemotherapy, especially when given in combination with anticancer drugs. However, the effectiveness [...] Read more.

The strategy utilizing trastuzumab, a humanized monoclonal antibody against human epidermal growth receptor 2 (HER-2), as a therapeutic agent in HER-2 positive breast cancer therapy seems to have advantage over traditional chemotherapy, especially when given in combination with anticancer drugs. However, the effectiveness of single antibody or antibody conjugated with chemotherapeutics is still far from ideal. Antibody–dendrimer conjugates hold the potential to improve the targeting and release of active substance at the tumor site. In the present study, we developed and synthesized PAMAM dendrimer–trastuzumab conjugates carrying doxorubicin (dox) specifically to cells overexpressing HER-2. ¹HNMR, FTIR and RP-HPLC were used to characterize the products and analyze their purity. Toxicity of PAMAM–trastuzumab and PAMAM–dox–trastuzumab conjugates compared with free trastuzumab and doxorubicin towards HER-2 positive (SKBR-3) and negative (MCF-7) human breast cancer cell lines was determined using MTT assay. Furthermore, the cellular uptake and cellular localization were studied by flow cytometry and confocal microscopy, respectively. A cytotoxicity profile of above mentioned compounds indicated that conjugate PAMAM–dox–trastuzumab was more effective when compared to free drug or the conjugate PAMAM–trastuzumab. Moreover, these results reveal that trastuzumab can be used as a targeting agent in PAMAM–dox–trastuzumab conjugate. Therefore PAMAM–dox–trastuzumab conjugate might be an interesting proposition which could lead to improvements in the effectiveness of drug delivery systems for tumors that overexpress HER-2. Full article

(This article belongs to the Special Issue Polymers for Therapy and Diagnostics)

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9 pages, 1408 KiB

Open AccessArticle

Tuning Light Emission towards White Light from a Naphthalenediimide-Based Entangled Metal-Organic Framework by Mixing Aromatic Guest Molecules

by Rebeca Sola-Llano¹

, Virginia Martínez-Martínez^1,*

, Shuhei Furukawa², Yohei Takashima³ and Iñigo López-Arbeloa¹

¹ Departamento de Química Física, Universidad del País Vasco, UPV/EHU, Apartado 644, 48080 Bilbao, Spain

² Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida, Kyoto 606-8501, Japan

³ Department of Nanobiochemistry, Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20 Minatojimaminamimachi, Chuo-ku, Kobe 650-0047, Japan

Polymers 2018, 10(2), 188; https://doi.org/10.3390/polym10020188 - 14 Feb 2018

Cited by 7 | Viewed by 5096

Abstract

Taking advantage of the outstanding properties of a naphthalenediimide-based entangled porous coordination polymer, a simple strategy for the achievement of white light emission is herein presented. The dynamic structural transformation of the [Zn₂(bdc)₂(dpNDI)]_n metal-organic framework enhances the interactions [...] Read more.

Taking advantage of the outstanding properties of a naphthalenediimide-based entangled porous coordination polymer, a simple strategy for the achievement of white light emission is herein presented. The dynamic structural transformation of the [Zn₂(bdc)₂(dpNDI)]_n metal-organic framework enhances the interactions with aryl-guests giving rise to different luminescence colors upon UV (ultraviolet) illumination. Thus, through the rational selection of those small aromatic guest molecules with different electron donor substituents at the appropriate proportion, the emission color was tuned by mixture ratio of guest molecules and even white light emission was achieved. Furthermore, domains in large crystals with a complementary response to linearly polarized light were noticed. Full article

(This article belongs to the Special Issue Polymeric Materials for Optical Applications)

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10 pages, 2052 KiB

Open AccessArticle

α-Cyclodextrins Polyrotaxane Loading Silver Sulfadiazine

by Sa Liu^1,2, Chunting Zhong^1,2, Weiwei Wang^1,2, Yongguang Jia^1,2, Lin Wang^1,2 and Li Ren^1,2,*

¹ School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, China

² National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006, China

Polymers 2018, 10(2), 190; https://doi.org/10.3390/polym10020190 - 14 Feb 2018

Cited by 7 | Viewed by 4227

Abstract

As a drug carrier, polyrotaxane (PR) has been used for targeted delivery and sustained release of drugs, whereas silver sulfadiazine (SD-Ag) is an emerging antibiotic agent. PR was synthesized by the use of α-cyclodextrin (CD) and poly(ethylene glycol) (PEG), and a specific antibacterial [...] Read more.

As a drug carrier, polyrotaxane (PR) has been used for targeted delivery and sustained release of drugs, whereas silver sulfadiazine (SD-Ag) is an emerging antibiotic agent. PR was synthesized by the use of α-cyclodextrin (CD) and poly(ethylene glycol) (PEG), and a specific antibacterial material (PR-(SD-Ag)) was then prepared by loading SD-Ag onto PR with different mass ratios. The loading capacity and the encapsulation efficiency were 90% at a mass ratio of 1:1 of PR and SD-Ag. SD-Ag was released stably and slowly within 6 d in vitro, and its cumulative release reached more than 85%. The mechanism of PR loading SD-Ag might be that SD-Ag attached to the edge of α-CD through hydrogen bonding. PR-(SD-Ag) showed a higher light stability than SD-Ag and held excellent antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Full article

(This article belongs to the Special Issue Host-Guest Polymer Complexes)

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16 pages, 3074 KiB

Open AccessArticle

Comparative Investigation on the Performance of Modified System Poles and Traditional System Poles Obtained from PDC Data for Diagnosing the Ageing Condition of Transformer Polymer Insulation Materials

by Jiefeng Liu^1,2,†

, Hanbo Zheng^1,3,*,†

, Yiyi Zhang^1,4,*,†

, Tianchun Zhou⁵, Jie Zhao², Jiaqi Li², Jingqing Liu² and Jichang Li²

¹ Guangxi Key Laboratory of Power System Optimization and Energy Technology, Guangxi University, Nanning 530004, Guangxi, China

² Shijiazhuang Power Supply Branch of State Grid Electric Power Company, Shijiazhuang 050000, Hebei, China

³ State Grid Henan Electric Power Research Institute, Zhengzhou 450052, Henan, China

⁴ National Demonstration Center for Experimental Electrical Engineering Education, Guangxi University, Nanning 530004, Guangxi, China

⁵ Electric Power Planning & Engineering Institute, Xicheng District, Beijing 100120, China

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 191; https://doi.org/10.3390/polym10020191 - 14 Feb 2018

Cited by 12 | Viewed by 4558

Abstract

The life expectancy of a transformer is largely depended on the service life of transformer polymer insulation materials. Nowadays, several papers have reported that the traditional system poles obtained from polarization and depolarization current (PDC) data can be used to assess the condition [...] Read more.

The life expectancy of a transformer is largely depended on the service life of transformer polymer insulation materials. Nowadays, several papers have reported that the traditional system poles obtained from polarization and depolarization current (PDC) data can be used to assess the condition of transformer insulation systems. However, the traditional system poles technique only provides limited ageing information for transformer polymer insulation. In this paper, the modified system poles obtained from PDC data are proposed to assess the ageing condition of transformer polymer insulation. The aim of the work is to focus on reporting a comparative investigation on the performance of modified system poles and traditional system poles for assessing the ageing condition of a transformer polymer insulation system. In the present work, a series of experiments have been performed under controlled laboratory conditions. The PDC measurement data, degree of polymerization (DP) and moisture content of the oil-immersed polymer pressboard specimens were carefully monitored. It is observed that, compared to the relationships between traditional system poles and DP values, there are better correlations between the modified system poles and DP values, because the modified system poles can obtain much more ageing information on transformer polymer insulation. Therefore, the modified system poles proposed in the paper are more suitable for the diagnosis of the ageing condition of transformer polymer insulation. Full article

(This article belongs to the Special Issue Polymers for Energy Applications)

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9 pages, 2092 KiB

Open AccessArticle

Affinity Capillary Electrochromatography of Molecularly Imprinted Thin Layers Grafted onto Silica Capillaries Using a Surface-Bound Azo-Initiator and Living Polymerization

by Cristina Giovannoli^1,*, Cinzia Passini¹, Fabio Di Nardo¹, Laura Anfossi¹

, Claudio Baggiani¹

and Ian A. Nicholls²

¹ Laboratory of Bioanalytical Chemistry, Department of Chemistry, Via Giuria 7, University of Torino, 10125, Torino, Italy

² Bioorganic & Biophysical Chemistry Laboratory, Centre for Biomaterials Chemistry, Department of Chemistry & Biomedical Sciences, Linnaeus University, SE-39182 Kalmar, Sweden

Polymers 2018, 10(2), 192; https://doi.org/10.3390/polym10020192 - 15 Feb 2018

Cited by 12 | Viewed by 3666

Abstract

Molecularly imprinted thin layers were prepared in silica capillaries by using two different surface polymerization strategies, the first using 4,4′-azobis(4-cyanovaleric acid) as a surface-coupled radical initiator, and the second, S-carboxypropyl-S’-benzyltrithiocarbonate as a reversible addition-fragmentation chain transfer (RAFT) agent in combination with 2,2′-azobisisobutyronitrile as [...] Read more.

Molecularly imprinted thin layers were prepared in silica capillaries by using two different surface polymerization strategies, the first using 4,4′-azobis(4-cyanovaleric acid) as a surface-coupled radical initiator, and the second, S-carboxypropyl-S’-benzyltrithiocarbonate as a reversible addition-fragmentation chain transfer (RAFT) agent in combination with 2,2′-azobisisobutyronitrile as a free radical initiator. The ability to generate imprinted thin layers was tested on two different polymerization systems: (i) a 4-vinylpyridine/ethylene dimethacrylate (4VP-EDMA) in methanol-water solution with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as a template; and (ii) methacrylic acid/ethylene dimethacrylate (MAA-EDMA) in a chloroform solution with warfarin as the template molecule. The binding properties of the imprinted capillaries were studied and compared with those of the corresponding non-imprinted polymer coated capillaries by injecting the template molecule and by measuring its migration times relative to a neutral and non-retained marker. The role of running buffer hydrophobicity on recognition was investigated by studying the influence of varying buffer acetonitrile concentration. The 2,4,5-T-imprinted capillary showed molecular recognition based on a reversed phase mechanism, with a decrease of the template recognition in the presence of higher acetonitrile content; whereas warfarin-imprinted capillaries showed a bell-shaped trend upon varying the acetonitrile percentage, illustrating different mechanisms underlying imprinted polymer-ligand recognition. Importantly, the results demonstrated the validity of affinity capillary electrochromatography (CEC) to screen the binding properties of imprinted layers. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers)

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18 pages, 5418 KiB

Open AccessArticle

Minimizing Freshwater Consumption in the Wash-Off Step in Textile Reactive Dyeing by Catalytic Ozonation with Carbon Aerogel Hosted Bimetallic Catalyst

by Enling Hu

, Songmin Shang^*

, Xiaoming Tao

, Shouxiang Jiang and Ka-Lok Chiu

Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong, China

Polymers 2018, 10(2), 193; https://doi.org/10.3390/polym10020193 - 15 Feb 2018

Cited by 13 | Viewed by 4968

Abstract

In textile reactive dyeing, dyed fabrics have to be rinsed in the wash-off step several times to improve colorfastness. Thus, the multiple rinsing processes drastically increase the freshwater consumption and meanwhile generate massive waste rinsing effluents. This paper addresses an innovative alternative to [...] Read more.

In textile reactive dyeing, dyed fabrics have to be rinsed in the wash-off step several times to improve colorfastness. Thus, the multiple rinsing processes drastically increase the freshwater consumption and meanwhile generate massive waste rinsing effluents. This paper addresses an innovative alternative to recycle the waste effluents to minimize freshwater consumption in the wash-off step. Accordingly, catalytic ozonation with a highly effective catalyst has been applied to remedy the waste rinsing effluents for recycling. The carbon aerogel (CA) hosted bimetallic hybrid material (Ag–Fe₂O₃@CA) was fabricated and used as the catalyst in the degradation of residual dyes in the waste rinsing effluents by ozonation treatments. The results indicate the participation of Ag–Fe₂O₃@CA had strikingly enhanced the removal percentage of chemical oxidation demand by 30%. In addition, it has been validated that waste effluents had been successfully reclaimed after catalytic ozonation with Ag–Fe₂O₃@CA. They could be additionally reused to reduce freshwater consumption in the wash-off step, but without sacrificing the color quality of corresponding fabrics in terms of color difference and colorfastness. This study may be the first to report the feasibility of catalytic ozonation in minimization of freshwater consumption in the wash-off step in textile reactive dyeing. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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16 pages, 3848 KiB

Open AccessArticle

Thermal Stability and Water Content Study of Void-Free Electrospun SPEEK/Cloisite Membrane for Direct Methanol Fuel Cell Application

by Nuha Awang^1,2, Juhana Jaafar^1,2,* and Ahmad Fauzi Ismail^1,2,*

¹ Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor Bahru, Malaysia

² Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor Bahru, Malaysia

Polymers 2018, 10(2), 194; https://doi.org/10.3390/polym10020194 - 15 Feb 2018

Cited by 33 | Viewed by 4954

Abstract

Void-free electrospun SPEEK/Cloisite15A^® densed (SP/e-spunCL) membranes are prepared. Different loadings of Cloisite15A^® (0.10, 0.15, 0.20, 0.25 and 0.30 wt %) are incorporated into electrospun fibers. The physico-chemical characteristics (methanol permeability, water uptake and proton conductivity) of the membranes are observed. Thermal [...] Read more.

Void-free electrospun SPEEK/Cloisite15A^® densed (SP/e-spunCL) membranes are prepared. Different loadings of Cloisite15A^® (0.10, 0.15, 0.20, 0.25 and 0.30 wt %) are incorporated into electrospun fibers. The physico-chemical characteristics (methanol permeability, water uptake and proton conductivity) of the membranes are observed. Thermal stability of all membranes is observed using Thermal Gravimetry Analysis (TGA). The thrree stages of degradation range between 163.1 and 613.1 °C. Differential Scanning Calorimetry (DSC) is used to study the wettability of the membranes. SP/e-spunCL15 shows the lowest freezing bound water of 15.27%, which contributed to the lowest methanol permeability. The non-freezing bound water that proportionally increased with proton conductivity of SP/e-spunCL15 membrane is the highest, 10.60%. It is suggested that the electrospinning as the fabricating method has successfully exfoliated the Cloisite in the membrane surface structure, contributing to the decrease of methanol permeability, while the retained water has led to the enhancement of proton conductivity. This new fabrication method of SP/e-spunCL membrane is said to be a desirable polymer electrolyte membrane for future application in direct methanol fuel cell field. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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12 pages, 8415 KiB

Open AccessArticle

Investigation of Mechanical Properties of Silicone/Phosphor Composite Used in Light Emitting Diodes Package

by Yongjun Pan¹

, Fulong Zhu^1,*, Jiajie Fan²

, Jiaquan Tao¹, Xinxin Lin¹, Fengren Wang¹ and Lang Shi¹

¹ Institute of Microsystems, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China

² School of Mechanical and Electrical Engineering, Hohai University, 200 Jinling Bei Road, Changzhou 213022, China

Polymers 2018, 10(2), 195; https://doi.org/10.3390/polym10020195 - 15 Feb 2018

Cited by 22 | Viewed by 5833

Abstract

Mass fraction of phosphor in silicone and aging time play important roles in the optics and mechanical performance of the silicone that is used in the light emitting diode (LED) package. In this paper, the mechanical properties of silicone/phosphor composites are investigated experimentally [...] Read more.

Mass fraction of phosphor in silicone and aging time play important roles in the optics and mechanical performance of the silicone that is used in the light emitting diode (LED) package. In this paper, the mechanical properties of silicone/phosphor composites are investigated experimentally by separate tensile and compression tests. Distribution of the phosphors is observed by scanning electron microscopy (SEM) to ensure the homogeneity of the samples. Different loading rates are applied to study the silicone material’s rate-dependent properties. The experimental results of the tensile and compression test show that the Young’s modulus increases with the mass fraction of phosphor in silicone. Longer aging time stiffens the silicone composite and weakens the ductility of the materials. A three-dimensional model used cohesive zone material (CZM) between the interface of the phosphor particles, and matrix silicone is built up to study the degradation mechanism at a micro-scale level. The simulation results indicate that the diameter of particles in silicone also impacts its interface debonding and crack growth. The theoretical results concerning the mass fraction of phosphor are in good agreement with the experiments. Full article

(This article belongs to the Special Issue Mechanics of Emerging Polymers with Unprecedented Networks)

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14 pages, 8268 KiB

Open AccessArticle

Preparation of Biocolorant and Eco-Dyeing Derived from Polyphenols Based on Laccase-Catalyzed Oxidative Polymerization

by Fubang Wang^1,2,†, Jixian Gong^1,2,†, Xinqing Zhang^1,2

, Yanfei Ren^1,2 and Jianfei Zhang^1,2,*

¹ School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China

² Key Laboratory for Advanced Textile Composites of the Education Ministry of China, Tianjin 300387, China

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 196; https://doi.org/10.3390/polym10020196 - 15 Feb 2018

Cited by 33 | Viewed by 5826

Abstract

Natural products have been believed to be a promising source to obtain ecological dyes and pigments. Plant polyphenol is a kind of significant natural compound, and tea provides a rich source of polyphenols. In this study, biocolorant derived from phenolic compounds was generated [...] Read more.

Natural products have been believed to be a promising source to obtain ecological dyes and pigments. Plant polyphenol is a kind of significant natural compound, and tea provides a rich source of polyphenols. In this study, biocolorant derived from phenolic compounds was generated based on laccase-catalyzed oxidative polymerization, and eco-dyeing of silk and wool fabrics with pigments derived from tea was investigated under the influence of pH variation. This work demonstrated that the dyeing property was better under acidic conditions compared to alkalinity, and fixation rate was the best when pH value was 3. Furthermore, breaking strength of dyed fabrics sharply reduced under the condition of pH 11. Eventually, the dyeing method was an eco-friendly process, which was based on bioconversion, and no mordant was added during the process of dyeing. Full article

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18 pages, 4423 KiB

Open AccessArticle

Poly(mono/diethylene glycol n-tetradecyl ether vinyl ether)s with Various Molecular Weights as Phase Change Materials

by Dongfang Pei

, Sai Chen, Wei Li and Xingxiang Zhang^*

Tianjin Municipal Key Lab of Advanced Fiber and Energy Storage Technology, School of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China

Polymers 2018, 10(2), 197; https://doi.org/10.3390/polym10020197 - 15 Feb 2018

Cited by 3 | Viewed by 5961

Abstract

At present, research on the relationship of comb-like polymer phase change material structures and their heat storage performance is scarce. Therefore, this relationship from both micro and macro perspectives will be studied in this paper. In order to achieve a high phase change [...] Read more.

At present, research on the relationship of comb-like polymer phase change material structures and their heat storage performance is scarce. Therefore, this relationship from both micro and macro perspectives will be studied in this paper. In order to achieve a high phase change enthalpy, ethylene glycol segments were introduced between the vinyl and the alkyl side chains. A series of poly(mono/diethylene glycol n-tetradecyl ether vinyl ethers) (PC₁₄E_nVEs) (n = 1, 2) with various molecular weights were polymerized by living cationic polymerization. The results of PC₁₄E₁VE and PC₁₄E₂VE showed that the minimum number of carbon atoms required for side-chain crystallization were 7.7 and 7.2, which were lower than that reported in the literature. The phase change enthalpy 89 J/g (for poly(mono ethylene glycol n-tetradecyl ether vinyl ethers)) and 86 J/g (for poly(hexadecyl acrylate)) were approximately equal. With the increase of molecular weight, the melting temperature, the melting enthalpy, and the initial thermal decomposition temperature of PC₁₄E₁VE changed from 27.0 to 28.0 °C, from 95 to 89 J/g, and from 264 to 287 °C, respectively. When the number average molar mass of PC₁₄E_nVEs exceeded 20,000, the enthalpy values remained basically unchanged. The introduction of the ethylene glycol chain was conducive to the crystallization of alkyl side chains. Full article

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24 pages, 7183 KiB

Open AccessArticle

Thermally Induced Structural Transitions of Nylon 4 9 as a New Example of Even–Odd Polyamides

by Cristian Olmo¹, Maria Teresa Casas¹, Juan Carlos Martínez², Lourdes Franco^1,3,*

and Jordi Puiggalí^1,3,*

¹ Chemical Engineering Department, EEBE, Polytechnic University of Catalonia, Building I.2, C/Eduard Maristany 10-14, 08019 Barcelona, Spain

² ALBA Synchrotron Light Facility, Carrer de la llum 2-26, Cerdanyola del Vallès, 08290 Barcelona, Spain

³ Research Center for Multiscale Science and Engineering, Polytechnic University of Catalonia, C/Eduard Maristany 10-14, 08019 Barcelona, Spain

Polymers 2018, 10(2), 198; https://doi.org/10.3390/polym10020198 - 16 Feb 2018

Cited by 9 | Viewed by 7099

Abstract

Crystalline morphology and structure of nylon 4 9 have been studied by means of optical and transmission electron microscopies, and X-ray diffraction. Rhombic crystals were characteristic of crystallization from glycerin dilute solutions, although the final morphology was dependent on the crystallization temperature. In [...] Read more.

Crystalline morphology and structure of nylon 4 9 have been studied by means of optical and transmission electron microscopies, and X-ray diffraction. Rhombic crystals were characteristic of crystallization from glycerin dilute solutions, although the final morphology was dependent on the crystallization temperature. In any case, a single electron diffraction pattern was always obtained, being characteristic a 2 mm symmetry and reflections at spacings that were indicative of a projected rectangular unit cell with hydrogen bonds established along two planar directions (i.e., the diagonals of the unit cell), as it was determined from related polyamides. Crystallization from the melt gave rise to negative birefringent spherulites with a morphology (axialitic, speckled or ringed) that was dependent on the crystallization temperature. Kinetic analysis indicated that melt crystallization took place according to two growth mechanisms (Regimes II and III), which reflect distinct secondary nucleation rates. A complex polymorphic behavior on heating and cooling processes was evidenced by real time synchrotron experiments, being determined an intermediate crystalline structure as well as the typical pseudohexagonal arrangement associated to the Brill transition. Polymorphic transitions were highly dependent on the initial crystalline structure, being enhanced the structural transition from the low temperature structure to the intermediate one when traces of the latter were initially present. Calorimetric and infrared studies supported also the detected thermal transitions of nylon 4 9. Full article

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14 pages, 1511 KiB

Open AccessArticle

Mucoadhesive Cyclodextrin-Modified Thiolated Poly(aspartic acid) as a Potential Ophthalmic Drug Delivery System

by Mária Budai-Szűcs¹, Eszter L. Kiss¹, Barnabás Áron Szilágyi², András Szilágyi², Benjámin Gyarmati², Szilvia Berkó¹, Anita Kovács¹, Gabriella Horvát¹, Zoltán Aigner¹, Judit Soós³ and Erzsébet Csányi^1,*

¹ Institute of Pharmaceutical Technology and Regulatory Affairs, Faculty of Pharmacy, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary

² Soft Matters Group, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary

³ Department of Ophthalmology, Faculty of Medicine, University of Szeged, Korányi Fasor 10-11, H-6720 Szeged, Hungary

Polymers 2018, 10(2), 199; https://doi.org/10.3390/polym10020199 - 16 Feb 2018

Cited by 29 | Viewed by 6009

Abstract

Thiolated poly(aspartic acid) is known as a good mucoadhesive polymer in aqueous ophthalmic formulations. In this paper, cyclodextrin-modified thiolated poly(aspartic acid) was synthesized for the incorporation of prednisolone, a lipophilic ophthalmic drug, in an aqueous in situ gellable mucoadhesive solution. This polymer combines [...] Read more.

Thiolated poly(aspartic acid) is known as a good mucoadhesive polymer in aqueous ophthalmic formulations. In this paper, cyclodextrin-modified thiolated poly(aspartic acid) was synthesized for the incorporation of prednisolone, a lipophilic ophthalmic drug, in an aqueous in situ gellable mucoadhesive solution. This polymer combines the advantages of cyclodextrins and thiolated polymers. The formation of the cyclodextrin-drug complex in the gels was analyzed by X-ray powder diffraction. The ocular applicability of the polymer was characterized by means of physicochemical, rheological and drug diffusion tests. It was established that the chemical bonding of the cyclodextrin molecule did not affect the complexation of prednisolone, while the polymer solution preserved its in situ gellable and good mucoadhesive characteristics. The chemical immobilization of cyclodextrin modified the diffusion profile of prednisolone and prolonged drug release was observed. The combination of free and immobilized cyclodextrins provided the best release profile because the free complex can diffuse rapidly, while the bonded complex ensures a prolonged action. Full article

(This article belongs to the Collection Polysaccharides)

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11 pages, 2172 KiB

Open AccessArticle

Kinetics of Low Temperature Polyester Dyeing with High Molecular Weight Disperse Dyes by Solvent Microemulsion and AgroSourced Auxiliaries

by Shahram Radei, F. Javier Carrión-Fité, Mònica Ardanuy^*

and José María Canal

Secció Enginyeria Tèxtil, Departament de Ciència dels Materials i Enginyeria Metal.lúrgica, Universitat Politècnica de Catalunya, C/Colom 11, 08222 Terrassa, Spain

Polymers 2018, 10(2), 200; https://doi.org/10.3390/polym10020200 - 16 Feb 2018

Cited by 31 | Viewed by 8214

Abstract

This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a [...] Read more.

This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100 °C). Moreover, the dyeing rate constants, correlation coefficient and activation energies were proposed for this system. It was found that o-vanillin yielded higher dye absorption levels than coumarin, leading to exhaustions of 88% and 87% for Disperse Red 167 and Disperse Blue 79, respectively. K/S values of dyed polyester were also found to be higher for dye baths containing o-vanillin with respect to the ones with coumarin. In terms of hot pressing fastness and wash fastness, generally no adverse influence on fastness properties was reported, while o-vanillin showed slightly better results compared to coumarin. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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11 pages, 3119 KiB

Open AccessArticle

Renewable, Eugenol—Modified Polystyrene Layer for Liquid Crystal Orientation

by Changha Ju^†, Taehyung Kim^† and Hyo Kang^*

¹ Department of Chemical Engineering, Dong-A University, 37 Nakdong-Daero 550beon-gil, Saha-gu, Busan 604-714, Korea

^† The authors contributed equally to this work.

Polymers 2018, 10(2), 201; https://doi.org/10.3390/polym10020201 - 17 Feb 2018

Cited by 13 | Viewed by 7377

Abstract

We synthesized a series of plant-based and renewable, eugenol-modified polystyrene (PEUG#) (# = 20, 40, 60, 80, and 100, in which # is the molar content of the eugenol moiety in the side group). Eugenol is extracted from clove oil. We used polymer [...] Read more.

We synthesized a series of plant-based and renewable, eugenol-modified polystyrene (PEUG#) (# = 20, 40, 60, 80, and 100, in which # is the molar content of the eugenol moiety in the side group). Eugenol is extracted from clove oil. We used polymer modification reactions to determine the liquid crystal (LC) orientation properties of the polymer films. In general, the LC cells fabricated using the polymer films with a higher molar content of eugenol side groups exhibited vertical LC orientation behavior. The vertical orientation behavior was well correlated with the surface energy value of the polymer films. The vertical LC orientation could be formed due to the low polar surface energy value on the polymer film generated by the nonpolar carbon group. Electro-optical performances (e.g., voltage holding ratio (VHR), residual DC voltage (R-DC), and thermal orientation stabilities) were good enough to be observed for LC cells using PEUG100 polymer as an eco-friendly LC orientation material. Full article

(This article belongs to the Special Issue Polymers from Renewable Resources)

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21 pages, 7211 KiB

Open AccessArticle

Impact of Nanoclays on the Biodegradation of Poly(Lactic Acid) Nanocomposites

by Edgar Castro-Aguirre¹

, Rafael Auras^1,*

, Susan Selke¹, Maria Rubino¹ and Terence Marsh²

¹ School of Packaging, Michigan State University, East Lansing, MI 48824, USA

² Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA

Polymers 2018, 10(2), 202; https://doi.org/10.3390/polym10020202 - 17 Feb 2018

Cited by 82 | Viewed by 8839

Abstract

Poly(lactic acid) (PLA), a well-known biodegradable and compostable polymer, was used in this study as a model system to determine if the addition of nanoclays affects its biodegradation in simulated composting conditions and whether the nanoclays impact the microbial population in a compost [...] Read more.

Poly(lactic acid) (PLA), a well-known biodegradable and compostable polymer, was used in this study as a model system to determine if the addition of nanoclays affects its biodegradation in simulated composting conditions and whether the nanoclays impact the microbial population in a compost environment. Three different nanoclays were studied due to their different surface characteristics but similar chemistry: organo-modified montmorillonite (OMMT), Halloysite nanotubes (HNT), and Laponite® RD (LRD). Additionally, the organo-modifier of MMT, methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium (QAC), was studied. PLA and PLA bio-nanocomposite (BNC) films were produced, characterized, and used for biodegradation evaluation with an in-house built direct measurement respirometer (DMR) following the analysis of evolved CO2 approach. A biofilm formation essay and scanning electron microscopy were used to evaluate microbial attachment on the surface of PLA and BNCs. The results obtained from four different biodegradation tests with PLA and its BNCs showed a significantly higher mineralization of the films containing nanoclay in comparison to the pristine PLA during the first three to four weeks of testing, mainly attributed to the reduction in the PLA lag time. The effect of the nanoclays on the initial molecular weight during processing played a crucial role in the evolution of CO2. PLA-LRD5 had the greatest microbial attachment on the surface as confirmed by the biofilm test and the SEM micrographs, while PLA-QAC0.4 had the lowest biofilm formation that may be attributed to the inhibitory effect also found during the biodegradation test when the QAC was tested by itself. Full article

(This article belongs to the Special Issue Polymers from Renewable Resources)

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12 pages, 8565 KiB

Open AccessArticle

Effect of Polyhedral Oligomeric Silsesquioxane on the Melting, Structure, and Mechanical Behavior of Polyoxymethylene

by Dorota Czarnecka-Komorowska^* and Tomasz Sterzynski

Poznan University of Technology, Institute of Materials Technology, Polymer Processing Division, Piotrowo 3 Street, PL-61138 Poznan, Poland

Polymers 2018, 10(2), 203; https://doi.org/10.3390/polym10020203 - 17 Feb 2018

Cited by 21 | Viewed by 5260

Abstract

The effects of octakis[(3-glycidoxypropyl)dimethylsiloxy]octasilsesquioxane (GPOSS) on the crystallinity, crystal structure, morphology, and mechanical properties of polyoxymethylene (POM) and POM/GPOSS composites were investigated. The POM/GPOSS composites with varying concentrations of GPOSS nanoparticles (0.05–0.25 wt %) were prepared via melt blending. The structure of POM/GPOSS [...] Read more.

The effects of octakis[(3-glycidoxypropyl)dimethylsiloxy]octasilsesquioxane (GPOSS) on the crystallinity, crystal structure, morphology, and mechanical properties of polyoxymethylene (POM) and POM/GPOSS composites were investigated. The POM/GPOSS composites with varying concentrations of GPOSS nanoparticles (0.05–0.25 wt %) were prepared via melt blending. The structure of POM/GPOSS composites was characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and polarized light microscopy (PLM). The mechanical properties were determined by standardized tensile tests. The morphology and dispersion of GPOSS nanoparticles in the POM matrix were investigated with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. It was observed that the dispersion of the GPOSS nanoparticles was uniform. Based on DSC studies, it was found that the melting temperature, lamellar thickness, and the degree of crystallinity of the POM/GPOSS composites increased. The POM/GPOSS composites showed an increased Young’s modulus and tensile strength. Finally, compared with the pure POM, the addition of GPOSS reduced the spherulites’ size and improved the crystallinity of the POM, which demonstrates that the nucleation effect of GPOSS is favorable for the mechanical properties of POM. Full article

(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)

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21 pages, 3040 KiB

Open AccessArticle

Neodymium Recovery by Chitosan/Iron(III) Hydroxide [ChiFer(III)] Sorbent Material: Batch and Column Systems

by Hary Demey^1,2,*

, Byron Lapo^1,3

, Montserrat Ruiz⁴, Agustin Fortuny⁴, Muriel Marchand² and Ana M. Sastre¹

¹ Department of Chemical Engineering, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain

² Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DRT/LITEN/DTBH/LTB, 17 rue des Martrys, 38054 Grenoble, France

³ School of Chemical Engineering, Universidad Técnica de Machala, UACQS, 070151 Machala, Ecuador

⁴ Department of Chemical Engineering, Universitat Politècnica de Catalunya, EPSEVG, Av. Víctor Balaguer, s/n, 08800 Vilanova i la Geltrú, Spain

Polymers 2018, 10(2), 204; https://doi.org/10.3390/polym10020204 - 19 Feb 2018

Cited by 37 | Viewed by 6635

Abstract

A low cost composite material was synthesized for neodymium recovery from dilute aqueous solutions. The in-situ production of the composite containing chitosan and iron(III) hydroxide (ChiFer(III)) was improved and the results were compared with raw chitosan particles. The sorbent was characterized using Fourier [...] Read more.

A low cost composite material was synthesized for neodymium recovery from dilute aqueous solutions. The in-situ production of the composite containing chitosan and iron(III) hydroxide (ChiFer(III)) was improved and the results were compared with raw chitosan particles. The sorbent was characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive X-ray analyses (SEM-EDX). The equilibrium studies were performed using firstly a batch system, and secondly a continuous system. The sorption isotherms were fitted with the Langmuir, Freundlich, and Sips models; experimental data was better described with the Langmuir equation and the maximum sorption capacity was 13.8 mg g-1 at pH 4. The introduction of iron into the biopolymer matrix increases by four times the sorption uptake of the chitosan; the individual sorption capacity of iron (into the composite) was calculated as 30.9 mg Nd/g Fe. The experimental results of the columns were fitted adequately using the Thomas model. As an approach to Nd-Fe-B permanent magnets effluents, a synthetic dilute effluent was simulated at pH 4, in order to evaluate the selectivity of the sorbent material; the overshooting of boron in the column system confirmed the higher selectivity toward neodymium ions. The elution step was carried out using MilliQ-water with the pH set to 3.5 (dilute HCl solution). Full article

(This article belongs to the Special Issue Advances in Chitin/Chitosan Characterization and Applications)

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14 pages, 2675 KiB

Open AccessArticle

Preparation of Water-soluble Polyion Complex (PIC) Micelles Covered with Amphoteric Random Copolymer Shells with Pendant Sulfonate and Quaternary Amino Groups

by Rina Nakahata and Shin-ichi Yusa^*

Department of Applied Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan

Polymers 2018, 10(2), 205; https://doi.org/10.3390/polym10020205 - 19 Feb 2018

Cited by 15 | Viewed by 7068

Abstract

An amphoteric random copolymer (P(SA)₉₁) composed of anionic sodium 2-acrylamido-2-methylpropanesulfonate (AMPS, S) and cationic 3-acrylamidopropyl trimethylammonium chloride (APTAC, A) was prepared via reversible addition-fragmentation chain transfer (RAFT) radical polymerization. The subscripts in the abbreviations indicate the degree of polymerization (DP). Furthermore, [...] Read more.

An amphoteric random copolymer (P(SA)₉₁) composed of anionic sodium 2-acrylamido-2-methylpropanesulfonate (AMPS, S) and cationic 3-acrylamidopropyl trimethylammonium chloride (APTAC, A) was prepared via reversible addition-fragmentation chain transfer (RAFT) radical polymerization. The subscripts in the abbreviations indicate the degree of polymerization (DP). Furthermore, AMPS and APTAC were polymerized using a P(SA)₉₁ macro-chain transfer agent to prepare an anionic diblock copolymer (P(SA)₉₁S₆₇) and a cationic diblock copolymer (P(SA)₉₁A₈₈), respectively. The DP was estimated from quantitative 13C NMR measurements. A stoichiometrically charge neutralized mixture of the aqueous P(SA)₉₁S₆₇ and P(SA)₉₁A₈₈ formed water-soluble polyion complex (PIC) micelles comprising PIC cores and amphoteric random copolymer shells. The PIC micelles were in a dynamic equilibrium state between PIC micelles and charge neutralized small aggregates composed of a P(SA)₉₁S₆₇/P(SA)₉₁A₈₈ pair. Interactions between PIC micelles and fetal bovine serum (FBS) in phosphate buffered saline (PBS) were evaluated by changing the hydrodynamic radius (R_h) and light scattering intensity (LSI). Increases in R_h and LSI were not observed for the mixture of PIC micelles and FBS in PBS for one day. This observation suggests that there is no interaction between PIC micelles and proteins, because the PIC micelle surfaces were covered with amphoteric random copolymer shells. However, with increasing time, the diblock copolymer chains that were dissociated from PIC micelles interacted with proteins. Full article

(This article belongs to the Special Issue Polymer Micelles)

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9 pages, 7320 KiB

Open AccessArticle

Self-Sensitization and Photo-Polymerization of Diacetylene Molecules Self-Assembled on a Hexagonal-Boron Nitride Nanosheet

by Elisseos Verveniotis^1,*, Yuji Okawa^1,*

, Kenji Watanabe²

, Takashi Taniguchi², Takaaki Taniguchi¹, Minoru Osada¹, Christian Joachim^1,3 and Masakazu Aono¹

¹ International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

² Research Center for Functional Materials, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

³ Centre d’Elaboration de Matériaux et d’Études Structurales (CEMES), Centre National de la Recherche Scientifique (CNRS), 29 rue J. Marvig, 31055 Toulouse CEDEX, France

Polymers 2018, 10(2), 206; https://doi.org/10.3390/polym10020206 - 19 Feb 2018

Cited by 7 | Viewed by 6706

Abstract

Long poly-diacetylene chains are excellent candidates for planar, on-surface synthesized molecular electronic wires. Since hexagonal-Boron Nitride (h-BN) was identified as the best available atomically flat insulator for the deposition of poly-diacetylene precursors, we demonstrate the polymerization patterns and rate on it under UV-light [...] Read more.

Long poly-diacetylene chains are excellent candidates for planar, on-surface synthesized molecular electronic wires. Since hexagonal-Boron Nitride (h-BN) was identified as the best available atomically flat insulator for the deposition of poly-diacetylene precursors, we demonstrate the polymerization patterns and rate on it under UV-light irradiation, with subsequent polymer identification by atomic force microscopy. The results on h-BN indicate self-sensitization which yields blocks comprised of several polymers, unlike on the well-studied graphite/diacetylene system, where the polymers are always isolated. In addition, the photo-polymerization proceeds at least 170 times faster on h-BN, where it also results in longer polymers. Both effects are explained by the h-BN bandgap, which is larger than the diacetylene electronic excitation energy, thus allowing the transfer of excess energy absorbed by polymerized wires to adjacent monomers, triggering their polymerization. This work sets the stage for conductance measurements of single molecular poly-diacetylene wires on h-BN. Full article

(This article belongs to the Special Issue Polymerizations from Surfaces)

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14 pages, 4634 KiB

Open AccessArticle

Controlled Surface Modification of Polyamide 6.6 Fibres Using CaCl2/H2O/EtOH Solutions

by Barbara Rietzler, Thomas Bechtold

and Tung Pham^*

Research Institute of Textile Chemistry and Textile Physics, Leopold-Franzens University Innsbruck, Höchsterstraße 73, 6850 Dornbirn, Austria

Polymers 2018, 10(2), 207; https://doi.org/10.3390/polym10020207 - 21 Feb 2018

Cited by 30 | Viewed by 7860

Abstract

Polyamide 6.6 is one of the most widely used polymers in the textile industry due to its durability; however, it has rather limited modification potential. In this work, the controlled surface modification of polyamide 6.6 fibres using the solvent system CaCl2/H2O/EtOH was studied. [...] Read more.

Polyamide 6.6 is one of the most widely used polymers in the textile industry due to its durability; however, it has rather limited modification potential. In this work, the controlled surface modification of polyamide 6.6 fibres using the solvent system CaCl2/H2O/EtOH was studied. The effects of solvent composition (relative proportions of the three components) and treatment time on fibre properties were studied both in situ (with fibres in solvent) and ex situ (after the solvent was washed off). The fibres swell and/or dissolve in the solvent depending on its composition and the treatment time. We believe that the fibre–solvent interaction is through complex formation between the fibre carbonyl groups and the CaCl2. On washing, there is decomplexation and precipitation of the polymer. The treated fibres exhibit greater diameters and surface roughness, structural difference between an outer shell and an inner core is observable, and water retention is higher. The solvent system is more benign than current alternatives, and through suitable tailoring of the treatment conditions, e.g., composition and time, it may be used in the design of advanced materials for storage and release of active substances. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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20 pages, 5954 KiB

Open AccessArticle

Electrospun Gelatin–Chondroitin Sulfate Scaffolds Loaded with Platelet Lysate Promote Immature Cardiomyocyte Proliferation

by Francesca Saporito¹, Giuseppina Sandri^1,*

, Maria Cristina Bonferoni¹, Silvia Rossi¹

, Lorenzo Malavasi², Claudia Del Fante³, Barbara Vigani¹, Lauren Black⁴

and Franca Ferrari¹

¹ Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy

² Department of Chemistry, Physical Chemistry Section, University of Pavia, Viale Taramelli 16, 27100 Pavia, Italy

³ Immunohaematology and Transfusion Service, Apheresis and Cell Therapy Unit, Fondazione IRCCS Policlinico S. Matteo, Viale Golgi 19, Pavia 27100, Italy

⁴ Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA

Polymers 2018, 10(2), 208; https://doi.org/10.3390/polym10020208 - 21 Feb 2018

Cited by 28 | Viewed by 5601

Abstract

The aim of the present work was the development of heart patches based on gelatin (G) and chondroitin sulfate (CS) to be used as implants to improve heart recovery after corrective surgery for critical congenital heart defects (CHD). Patches were prepared by means [...] Read more.

The aim of the present work was the development of heart patches based on gelatin (G) and chondroitin sulfate (CS) to be used as implants to improve heart recovery after corrective surgery for critical congenital heart defects (CHD). Patches were prepared by means of electrospinning to obtain nanofibrous scaffolds and they were loaded with platelet lysate (PL) as a source of growth factors to further enhance the repair process. Scaffolds were characterized for morphology and mechanical properties and for the capability to support in vitro adhesion and proliferation of dermal fibroblasts in order to assess the system’s general biocompatibility. Adhesion and proliferation of endothelial cells and cardiac cells (cardiomyocytes and cardiac fibroblasts from rat fetuses) onto PL-loaded patches was evaluated. Patches presented good elasticity and high stiffness suitable for in vivo adaptation to heart contraction. CS improved adhesion and proliferation of dermal fibroblasts, as proof of their biocompatibility. Moreover, they enhanced the adhesion and proliferation of endothelial cells, a crucial mediator of cardiac repair. Cell adhesion and proliferation could be related to elastic properties, which could favor cell motility. The presence of platelet lysate and CS was crucial for the adhesion and proliferation of cardiac cells and, in particular, of cardiomyocytes: G/CS scaffold embedded with PL appeared to selectively promote proliferation in cardiomyocytes but not cardiac fibroblasts. In conclusion, G/CS scaffold seems to be a promising system to assist myocardial-repair processes in young patient, preserving cardiomyocyte viability and preventing cardiac fibroblast proliferation, likely reducing subsequent uncontrolled collagen deposition by fibroblasts following repair. Full article

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14 pages, 3598 KiB

Open AccessArticle

A 3D Stable Metal–Organic Framework for Highly Efficient Adsorption and Removal of Drug Contaminants from Water

by Zhidong Luo^†, Shuran Fan^†, Jianqiang Liu^*

, Weicong Liu, Xin Shen, Chuangpeng Wu, Yijia Huang, Gaoxiang Huang, Hui Huang and Mingbin Zheng^*

¹ Dongguan Key Laboratory of Drug Design and Formulation Technology, Key Laboratory of Research and Development of New Medical Materials of Guangdong Medical University, School of Pharmacy, Guangdong Medical University, Dongguan 523808, China

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 209; https://doi.org/10.3390/polym10020209 - 22 Feb 2018

Cited by 56 | Viewed by 6141

Abstract

We herein selected a 3D metal–organic framework decorated with carboxylate groups as an adsorbent to remove the pharmaceutical molecules of diclofenac sodium and chlorpromazine hydrochloride from water. The experiment aimed at exploring the effect factors of initial concentration, equilibrium time, temperature, pH and [...] Read more.

We herein selected a 3D metal–organic framework decorated with carboxylate groups as an adsorbent to remove the pharmaceutical molecules of diclofenac sodium and chlorpromazine hydrochloride from water. The experiment aimed at exploring the effect factors of initial concentration, equilibrium time, temperature, pH and adsorbent dosage on the adsorption process. The adsorption uptake rate of the diclofenac sodium is much higher than that of the chlorpromazine hydrochloride. This paper presents the high adsorption capacity of diclofenac sodium, in which porous MOFs are used for the removal of drug contaminants from water. According to linear fitting with adsorption isotherm equation and kinetic equations, diclofenac sodium conforms to the Langmuir model and pseudo-first-order kinetic equation, while chlorpromazine hydrochloride accords with the Temkin model and pseudo-second-order kinetic equation. The results of the study indicate that the title compound could be a promising hybrid material for removing diclofenac sodium and chlorpromazine hydrochloride from wastewater. Full article

(This article belongs to the Special Issue Coordination Polymer)

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17 pages, 4604 KiB

Open AccessArticle

Application of Superabsorbent Spacer Fabrics as Exuding Wound Dressing

by Yadie Yang and Hong Hu^*

Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Polymers 2018, 10(2), 210; https://doi.org/10.3390/polym10020210 - 22 Feb 2018

Cited by 34 | Viewed by 8696

Abstract

Exuding wound care requires a dressing to quickly absorb exudates and properly manage moisture during the healing process. In this study, the superabsorbent spacer fabrics were designed and fabricated for application in exuding wound dressings. The fabric structure consists of three layers, including [...] Read more.

Exuding wound care requires a dressing to quickly absorb exudates and properly manage moisture during the healing process. In this study, the superabsorbent spacer fabrics were designed and fabricated for application in exuding wound dressings. The fabric structure consists of three layers, including two outer hydrophobic layers made of polyester/spandex yarns and one superabsorbent middle layer made of superabsorbent yarns. In order to confirm the performance of these superabsorbent spacer fabrics, their dressing properties were tested and compared with two commercial foam dressings. The results showed that all the superabsorbent spacer fabrics had much faster wetting speeds (less than 2 s) than the foam dressings (6.04 s for Foam A and 63.69 s for Foam B). The absorbency of the superabsorbent spacer fabrics was at least twice higher than that of the foam dressings. The air permeability of the superabsorbent spacer fabrics (higher than 15 mL/s/cm² at 100 Pa) was much higher than that of the foam dressings which had a too low permeability to be measured by the testing device. In addition, the water vapor permeability, thermal insulation, and conformability of superabsorbent spacer fabrics were comparable to foam dressings. The study indicates that the superabsorbent spacer fabrics are suitable for exuding wound dressing applications. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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14 pages, 3381 KiB

Open AccessArticle

α-Cyclodextrin and α-Cyclodextrin Polymers as Oxygen Nanocarriers to Limit Hypoxia/Reoxygenation Injury: Implications from an In Vitro Model

by Saveria Femminò^1,†

, Claudia Penna^1,†, Federica Bessone², Fabrizio Caldera³

, Nilesh Dhakar³, Daniele Cau¹, Pasquale Pagliaro¹, Roberta Cavalli² and Francesco Trotta^3,*

¹ Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy

² Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy

³ Department of Chemistry, University of Turin, 10125 Turin, Italy

^† These authors contributed equally to this work.

Polymers 2018, 10(2), 211; https://doi.org/10.3390/polym10020211 - 22 Feb 2018

Cited by 39 | Viewed by 5690

Abstract

The incidence of heart failure (HF) is increasing worldwide and myocardial infarction (MI), which follows ischemia and reperfusion (I/R), is often at the basis of HF development. Nanocarriers are interesting particles for their potential application in cardiovascular disease. Impaired drug delivery in ischemic [...] Read more.

The incidence of heart failure (HF) is increasing worldwide and myocardial infarction (MI), which follows ischemia and reperfusion (I/R), is often at the basis of HF development. Nanocarriers are interesting particles for their potential application in cardiovascular disease. Impaired drug delivery in ischemic disease is challenging. Cyclodextrin nanosponges (NS) can be considered innovative tools for improving oxygen delivery in a controlled manner. This study has developed new α-cyclodextrin-based formulations as oxygen nanocarriers such as native α-cyclodextrin (α-CD), branched α-cyclodextrin polymer (α-CD POLY), and α-cyclodextrin nanosponges (α-CD NS). The three different α-CD-based formulations were tested at 0.2, 2, and 20 µg/mL to ascertain their capability to reduce cell mortality during hypoxia and reoxygenation (H/R) in vitro protocols. H9c2, a cardiomyoblast cell line, was exposed to normoxia (20% oxygen) or hypoxia (5% CO₂ and 95% N₂). The different formulations, applied before hypoxia, induced a significant reduction in cell mortality (in a range of 15% to 30%) when compared to samples devoid of oxygen. Moreover, their application at the beginning of reoxygenation induced a considerable reduction in cell death (12% to 20%). α-CD NS showed a marked efficacy in controlled oxygenation, which suggests an interesting potential for future medical application of polymer systems for MI treatment. Full article

(This article belongs to the Collection Polysaccharides)

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14 pages, 3305 KiB

Open AccessArticle

Special Resins for Stereolithography: In Situ Generation of Silver Nanoparticles

by Gabriele Taormina¹

, Corrado Sciancalepore², Federica Bondioli¹

and Massimo Messori^3,*

¹ Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181/A, 43124 Parma, Italy

² INSTM, National Interuniversity Consortium of Materials Science and Technology, Via Giusti 9, 50121 Florence, Italy

³ Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Pietro Vivarelli 10/1, 41121 Modena, MO, Italy

Polymers 2018, 10(2), 212; https://doi.org/10.3390/polym10020212 - 22 Feb 2018

Cited by 55 | Viewed by 8520

Abstract

The limited availability of materials with special properties represents one of the main limitations to a wider application of polymer-based additive manufacturing technologies. Filled resins are usually not suitable for vat photo-polymerization techniques such as stereolithography (SLA) or digital light processing (DLP) due [...] Read more.

The limited availability of materials with special properties represents one of the main limitations to a wider application of polymer-based additive manufacturing technologies. Filled resins are usually not suitable for vat photo-polymerization techniques such as stereolithography (SLA) or digital light processing (DLP) due to a strong increment of viscosity derived from the presence of rigid particles within the reactive suspension. In the present paper, the possibility to in situ generate silver nanoparticles (AgNPs) starting from a homogeneous liquid system containing a well dispersed silver salt, which is subsequently reduced to metallic silver during stereolithographic process, is reported. The simultaneous photo-induced cross-linking of the acrylic resin produces a filled thermoset resin with thermal-mechanical properties significantly enhanced with respect to the unfilled resin, even at very low AgNPs concentrations. With this approach, the use of silver salts having carbon-carbon double bonds, such as silver acrylate and silver methacrylate, allows the formation of a nanocomposite structure in which the release of by-products is minimized due to the active role of all the reactive components in the three dimensional (3D)-printing processes. The synergy, between this nano-technology and the geometrical freedom offered by SLA, could open up a wide spectrum of potential applications for such a material, for example in the field of food packaging and medical and healthcare sectors, considering the well-known antimicrobial effects of silver nanoparticles. Full article

(This article belongs to the Special Issue Thermosets)

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18 pages, 6940 KiB

Open AccessArticle

Novel Amphiphilic, Biodegradable, Biocompatible, Thermo-Responsive ABA Triblock Copolymers Based on PCL and PEG Analogues via a Combination of ROP and RAFT: Synthesis, Characterization, and Sustained Drug Release from Self-Assembled Micelles

by Wenyan Ning, Pei Shang, Jie Wu, Xiaoyu Shi and Shouxin Liu^*

Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, China

Polymers 2018, 10(2), 214; https://doi.org/10.3390/polym10020214 - 22 Feb 2018

Cited by 29 | Viewed by 8658

Abstract

Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type triblock copolymers, poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate]-b-poly(ε-caprolactone)-b-poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate] [P(MEO₂MA-co-OEGMA)-b-PCL-b-P(MEO₂MA-co-OEGMA)] (tBPs), were [...] Read more.

Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type triblock copolymers, poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate]-b-poly(ε-caprolactone)-b-poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate] [P(MEO₂MA-co-OEGMA)-b-PCL-b-P(MEO₂MA-co-OEGMA)] (tBPs), were synthesized via a combination of ring-opening polymerization (ROP) of ε-caprolactone (εCL) and reversible addition-fragmentation chain transfer polymerization (RAFT) of MEO₂MA and OEGMA comonomers. The chemical structures and compositions of these copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H NMR). The molecular weights of the copolymers were obtained using gel permeation chromatography (GPC) measurements. Thermo-responsive micelles were obtained by self-assembly of copolymers in aqueous medium. The temperature sensitivity and micelllization behavior of amphiphilic triblock copolymers solutions were studied by transmittance, fluorescence probe, surface tension, dynamic light scattering (DLS) and transmission electron microscopy (TEM). A hydrophobic drug, anethole, was encapsulated in micelles by using the dialysis method. The average particle sizes of drug-loaded micelles were determined by dynamic light scattering measurement. In vitro, the sustained release of the anethole was performed in pH 7.4 phosphate-buffered saline (PBS) at different temperatures. Results showed that the triblock copolymer’s micelles were quite effective in the encapsulation and controlled release of anethole. The vial inversion test demonstrated that the triblock copolymers could trigger the sol-gel transition which also depended on the temperature, and its sol-gel transition temperature gradually decreased with increasing concentration. The hydrogel system could also be used as a carrier of hydrophobic drugs in medicine. Full article

(This article belongs to the Special Issue Stimuli Responsive Polymers)

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15 pages, 1708 KiB

Open AccessArticle

Advantageous Microwave-Assisted Suzuki Polycondensation for the Synthesis of Aniline-Fluorene Alternate Copolymers as Molecular Model with Solvent Sensing Properties

by Rebeca Vázquez-Guilló¹, Alberto Falco¹

, M. José Martínez-Tomé¹, C. Reyes Mateo¹, María Antonia Herrero^2,3

, Ester Vázquez^2,3 and Ricardo Mallavia^1,*

¹ Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, E-03202 Elche, Spain

² Departamento de Química Inorgánica, Orgánica and Bioquímica, Facultad Ciencias y Tecnologías Químicas, Universidad Castilla La Mancha, E-13071 Ciudad Real, Spain

³ Instituto Regional de Investigación Científica Aplicada (IRICA), Edificio Marie Curie, Universidad Castilla La Mancha, E-13071 Ciudad Real, Spain

Polymers 2018, 10(2), 215; https://doi.org/10.3390/polym10020215 - 22 Feb 2018

Cited by 14 | Viewed by 6715

Abstract

Polymerization via Suzuki coupling under microwave (µW) irradiation has been studied for the synthesis of poly{1,4-(2/3-aminobenzene)-alt-2,7-(9,9-dihexylfluorene)} (PAF), chosen as molecular model. Briefly, µW-assisted procedures accelerated by two orders of magnitude the time required when using classical polymerization processes, and [...] Read more.

Polymerization via Suzuki coupling under microwave (µW) irradiation has been studied for the synthesis of poly{1,4-(2/3-aminobenzene)-alt-2,7-(9,9-dihexylfluorene)} (PAF), chosen as molecular model. Briefly, µW-assisted procedures accelerated by two orders of magnitude the time required when using classical polymerization processes, and the production yield was increased (>95%). In contrast, although the sizes of the polymers that were obtained by non-conventional heating reactions were reproducible and adequate for most applications, with this methodology the molecular weight of final polymers were not increased with respect to conventional heating. Asymmetric orientation of the amine group within the monomer and the assignments of each dyad or regioregularity, whose values ranged from 38% to 95% with this molecule, were analysed using common NMR spectroscopic data. Additionally, the synthesis of a new cationic polyelectrolyte, poly{1,4-(2/3-aminobenzene)-co-alt-2,7-[9,9´-bis(6’’-N,N,N-trimethylammonium-hexyl)fluorene]} dibromide (PAFAm), from poly{1,4-(2/3-aminobenzene)-co-alt-2,7-[9,9´-bis(6’’-bromohexyl)fluorene]} (PAFBr) by using previously optimized conditions for µW-assisted heating procedures was reported. Finally, the characterization of the final products from these batches showed unkown interesting solvatochromic properties of the PAF molecule. The study of the solvatochromism phenomena, which was investigated as a function of the polarity of the solvents, showed a well-defined Lippert correlation, indicating that the emission shift observed in PAF might be due to its interaction with surrounding environment. Proven high sensitivity to changes of its environment makes PAF a promising candidate of sensing applications. Full article

(This article belongs to the Special Issue Tailored Polymer Synthesis by Advanced Polymerization Techniques)

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14 pages, 4148 KiB

Open AccessArticle

Mechanism Analysis of Selective Adsorption and Specific Recognition by Molecularly Imprinted Polymers of Ginsenoside Re

by Wei Zhang^1,2

, Qian Li¹, Jingxiang Cong^1,2, Bofeng Wei^1,2 and Shaoyan Wang^1,2,*

¹ School of chemical engineering, University of science and technology, Liaoning, Anshan 114051, China

² Liaoning Provincial Key Laboratory of Fine Separation Technique, University of Science and Technology, Anshan 114051, China

Polymers 2018, 10(2), 216; https://doi.org/10.3390/polym10020216 - 22 Feb 2018

Cited by 19 | Viewed by 5170

Abstract

In this article, the molecularly imprinted polymers (MIPs) of ginsenoside Re (Re) were synthesized by suspension polymerization with Re as the template molecule, methacrylic acid (MAA) as the functional monomers, and ethyl glycol dimethacrylate (EGDMA) as the crosslinker. The MIPs were characterized by [...] Read more.

In this article, the molecularly imprinted polymers (MIPs) of ginsenoside Re (Re) were synthesized by suspension polymerization with Re as the template molecule, methacrylic acid (MAA) as the functional monomers, and ethyl glycol dimethacrylate (EGDMA) as the crosslinker. The MIPs were characterized by Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and surface porosity detector, and the selective adsorption and specific recognition of MIPs were analyzed using the theory of kinetics and thermodynamics. The experimental results showed that compared with non-imprinted polymers (NIPs), MIPs had a larger specific surface area and special pore structure and that different from the Langmuir model of NIPs, the static adsorption isotherm of MIPs for Re was in good agreement with the Freundlich model based on the two adsorption properties of MIPs. The curves of the adsorption dynamics and the lines of kinetic correlation indicate that there was a fast and selective adsorption equilibrium for Re because of the affinity of MIPs to the template rather than its analogue of ginsenoside Rg1 (Rg1). The study of thermodynamics indicate that the adsorption was controlled by enthalpy and that MIPs had higher enthalpy and entropy than NIPs, which contributed to the specific recognition of MIPs. Full article

(This article belongs to the Special Issue Mechanics of Emerging Polymers with Unprecedented Networks)

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8 pages, 3864 KiB

Open AccessCommunication

Nanosphere Lithography of Chitin and Chitosan with Colloidal and Self-Masking Patterning

by Rakkiyappan Chandran, Kyle Nowlin and Dennis R. LaJeunesse^*

Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina Greensboro, Greensboro, NC 27401, USA

Polymers 2018, 10(2), 218; https://doi.org/10.3390/polym10020218 - 23 Feb 2018

Cited by 9 | Viewed by 10783

Abstract

Complex surface topographies control, define, and determine the properties of insect cuticles. In some cases, these nanostructured materials are a direct extension of chitin-based cuticles. The cellular mechanisms that generate these elaborate chitin-based structures are unknown, and involve complicated cellular and biochemical “bottom-up” [...] Read more.

Complex surface topographies control, define, and determine the properties of insect cuticles. In some cases, these nanostructured materials are a direct extension of chitin-based cuticles. The cellular mechanisms that generate these elaborate chitin-based structures are unknown, and involve complicated cellular and biochemical “bottom-up” processes. We demonstrated that a synthetic “top-down” fabrication technique—nanosphere lithography—generates surfaces of chitin or chitosan that mimic the arrangement of nanostructures found on the surface of certain insect wings and eyes. Chitin and chitosan are flexible and biocompatible abundant natural polymers, and are a sustainable resource. The fabrication of nanostructured chitin and chitosan materials enables the development of new biopolymer materials. Finally, we demonstrated that another property of chitin and chitosan—the ability to self-assemble nanosilver particles—enables a novel and powerful new tool for the nanosphere lithographic method: the ability to generate a self-masking thin film. The scalability of the nanosphere lithographic technique is a major limitation; however, the silver nanoparticle self-masking enables a one-step thin-film cast or masking process, which can be used to generate nanostructured surfaces over a wide range of surfaces and areas. Full article

(This article belongs to the Special Issue Advances in Chitin/Chitosan Characterization and Applications)

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16 pages, 2421 KiB

Open AccessArticle

Synthesis of Waterborne Polyurethane by the Telechelic α,ω-Di(hydroxy)poly(n-butyl acrylate)

by Xin Chen, Chi Zhang, Weidong Li, Lei Chen and Wusheng Wang^*

School of Chemistry and Chemical Engineering, Anhui University, 111 Jiu long Road, Hefei 230601, China

Polymers 2018, 10(2), 219; https://doi.org/10.3390/polym10020219 - 23 Feb 2018

Cited by 7 | Viewed by 6157

Abstract

A key for the preparation of polyacrylate-based polyurethane is the synthesis of hydroxyl-terminated polyacrylate. To our knowledge, exactly one hydroxyl group of every polyacrylate chain has not been reported. The hydroxyl-terminated poly(butyl acrylate) (PBA) has been successfully synthesized by degenerative iodine transfer polymerization [...] Read more.

A key for the preparation of polyacrylate-based polyurethane is the synthesis of hydroxyl-terminated polyacrylate. To our knowledge, exactly one hydroxyl group of every polyacrylate chain has not been reported. The hydroxyl-terminated poly(butyl acrylate) (PBA) has been successfully synthesized by degenerative iodine transfer polymerization (DITP) of the n-butyl acrylate (n-BA) using 4,4′-azobis(4-cyano-1-pentanol) (ACPO) and diiodoxylene (DIX) as initiator and chain transfer agent, respectively, and subsequently substituted reaction of the iodine-terminated PBA with β-mercaptoethanol in alkaline condition. The latter reaction was highly efficient, and the terminal iodine at the end of polymer chains were almost quantitatively transformed to a hydroxyl group. 2,2′-Azobis(isobutyronitrile) (AIBN) and ACPO were used as initiators in the DITPs of n-BA. The results demonstrated that they had a significant influence on the terminal groups of the formed polymer chains. The structure, molecular weight, and molecular weight distribution of the hydroxyl-terminated PBA have been studied by ¹H, ¹³C NMR, and GPC results. The components of hydroxyl-terminated PBA were determined by MALDI-TOF MS spectra, and their formation is discussed. The broad molecular weight distribution of the PBA and the difference in the polymerization behaviors from typical living radical polymerization are explained based on the results of ¹H NMR and MALDI-TOF MS spectra. The hydroxyl-terminated PBA has been successfully used in the preparation of PBA-based polyurethane dispersions (PUDs). The aqueous PUDs were stable, and based on the DSC results it can be said that the miscibility of hard segments with PBA chains was improved. Full article

(This article belongs to the Special Issue Tailored Polymer Synthesis by Advanced Polymerization Techniques)

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17 pages, 4107 KiB

Open AccessArticle

Adsorption of Polyelectrolyte onto Nanosilica Synthesized from Rice Husk: Characteristics, Mechanisms, and Application for Antibiotic Removal

by Tien Duc Pham^1,*

, Thu Thuy Bui¹, Van Thanh Nguyen¹, Thi Kieu Van Bui¹, Thi Thuy Tran¹, Quynh Chi Phan², Tien Dat Pham³ and Thu Ha Hoang^3,*

¹ Faculty of Chemistry, VNU-University of Science, Vietnam National University, Hanoi, 19 Le Thanh Tong, Hoan Kiem, Hanoi 10000, Vietnam

² HUS High School for Gifted Students, Hanoi University of Science, Vietnam National University, Hanoi, 182 Luong The Vinh, Thanh Xuan, Hanoi 10000, Vietnam

³ High School of Education Sciences, University of Education, Vietnam National University, Hanoi, Kieu Mai, Phuc Dien, Bac Tu Liem, Hanoi 10000, Vietnam

Polymers 2018, 10(2), 220; https://doi.org/10.3390/polym10020220 - 23 Feb 2018

Cited by 79 | Viewed by 11760

Abstract

Adsorption of the polyelectrolyte polydiallyldimethylammonium chloride (PDADMAC) onto nanosilica (SiO₂) fabricated from rice husk was studied in this work. Nanosilica was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Adsorption of PDADMAC onto SiO₂ increased [...] Read more.

Adsorption of the polyelectrolyte polydiallyldimethylammonium chloride (PDADMAC) onto nanosilica (SiO₂) fabricated from rice husk was studied in this work. Nanosilica was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Adsorption of PDADMAC onto SiO₂ increased with increasing pH because the negative charge of SiO₂ is higher at high pH. Adsorption isotherms of PDADMAC onto silica at different KCl concentrations were fitted well by a two-step adsorption model. Adsorption mechanisms of PDADMAC onto SiO₂ are discussed on the basis of surface charge change, evaluation by ζ potential, surface modification by FTIR measurements, and the adsorption isotherm. The application of PDADMAC adsorption onto SiO₂ to remove amoxicillin antibiotic (AMX) was also studied. Experimental conditions such as contact time, pH, and adsorbent dosage for removal of AMX using SiO₂ modified with PDADMAC were systematically optimized and found to be 180 min, pH 10, and 10 mg/mL, respectively. The removal efficiency of AMX using PDADMAC-modified SiO₂ increased significantly from 19.1% to 92.3% under optimum adsorptive conditions. We indicate that PDADMAC-modified SiO₂ rice husk is a novel adsorbent for removal of antibiotics from aqueous solution. Full article

(This article belongs to the Special Issue Polymer-Based Nano-Sorbent Materials)

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13 pages, 2927 KiB

Open AccessArticle

Synthesis and Crosslinking of Polyether-Based Main Chain Benzoxazine Polymers and Their Gas Separation Performance

by Muntazim Munir Khan, Karabi Halder, Sergey Shishatskiy

and Volkan Filiz^*

Helmholtz-Zentrum Geesthacht, Institute of Polymer Research, Max-Planck-Strasse 1, 21502 Geesthacht, Germany

Polymers 2018, 10(2), 221; https://doi.org/10.3390/polym10020221 - 23 Feb 2018

Cited by 35 | Viewed by 11742

Abstract

The poly(ethylene glycol)-based benzoxazine polymers were synthesized via a polycondensation reaction between Bisphenol-A, paraformaldehyde, and poly(ether diamine)/(Jeffamine^®). The structures of the polymers were confirmed by proton nuclear magnetic resonance spectroscopy (¹H-NMR), indicating the presence of a cyclic benzoxazine ring. [...] Read more.

The poly(ethylene glycol)-based benzoxazine polymers were synthesized via a polycondensation reaction between Bisphenol-A, paraformaldehyde, and poly(ether diamine)/(Jeffamine^®). The structures of the polymers were confirmed by proton nuclear magnetic resonance spectroscopy (¹H-NMR), indicating the presence of a cyclic benzoxazine ring. The polymer solutions were casted on the glass plate and cross-linked via thermal treatment to produce tough and flexible films without using any external additives. Thermal properties and the crosslinking behaviour of these polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Single gas (H₂, O₂, N₂, CO₂, and CH₄) transport properties of the crosslinked polymeric membranes were measured by the time-lag method. The crosslinked PEG-based polybenzoxazine membranes show improved selectivities for CO₂/N₂ and CO₂/CH₄ gas pairs. The good separation selectivities of these PEG-based polybenzoxazine materials suggest their utility as efficient thin film composite membranes for gas and liquid membrane separation technology. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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14 pages, 3809 KiB

Open AccessArticle

Effects of Particle Size and Surface Chemistry on the Dispersion of Graphite Nanoplates in Polypropylene Composites

by Raquel M. Santos¹, Sacha T. Mould¹, Petr Formánek², Maria C. Paiva^1,*

and José A. Covas^1,*

¹ Institute for Polymers and Composites/I3N, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal

² Leibniz Institute for Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany

Polymers 2018, 10(2), 222; https://doi.org/10.3390/polym10020222 - 24 Feb 2018

Cited by 27 | Viewed by 6129

Abstract

Carbon nanoparticles tend to form agglomerates with considerable cohesive strength, depending on particle morphology and chemistry, thus presenting different dispersion challenges. The present work studies the dispersion of three types of graphite nanoplates (GnP) with different flake sizes and bulk densities in a [...] Read more.

Carbon nanoparticles tend to form agglomerates with considerable cohesive strength, depending on particle morphology and chemistry, thus presenting different dispersion challenges. The present work studies the dispersion of three types of graphite nanoplates (GnP) with different flake sizes and bulk densities in a polypropylene melt, using a prototype extensional mixer under comparable hydrodynamic stresses. The nanoparticles were also chemically functionalized by covalent bonding polymer molecules to their surface, and the dispersion of the functionalized GnP was studied. The effects of stress relaxation on dispersion were also analyzed. Samples were removed along the mixer length, and characterized by microscopy and dielectric spectroscopy. A lower dispersion rate was observed for GnP with larger surface area and higher bulk density. Significant re-agglomeration was observed for all materials when the deformation rate was reduced. The polypropylene-functionalized GnP, characterized by increased compatibility with the polymer matrix, showed similar dispersion effects, albeit presenting slightly higher dispersion levels. All the composites exhibit dielectric behavior, however, the alternate current (AC) conductivity is systematically higher for the composites with larger flake GnP. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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19 pages, 4860 KiB

Open AccessArticle

Multi-Alkenylsilsesquioxanes as Comonomers and Active Species Modifiers of Metallocene Catalyst in Copolymerization with Ethylene

by Paweł Groch^1,*

, Katarzyna Dziubek¹, Krystyna Czaja¹, Katarzyna Mituła² and Beata Dudziec^2,3

¹ Faculty of Chemistry, Opole University, Oleska 48, 45-052 Opole, Poland

² Faculty of Chemistry, Adam Mickiewicz University in Poznań, Umultowska 89B, 61-614 Poznań, Poland

³ Centre for Advanced Technologies, Adam Mickiewicz University in Poznań, Umultowska 89C, 61-614 Poznań, Poland

Polymers 2018, 10(2), 223; https://doi.org/10.3390/polym10020223 - 24 Feb 2018

Cited by 9 | Viewed by 5391

Abstract

The copolymers of ethylene (E) with open-caged iso-butyl-substituted tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) and phenyl-substituted tetra-alkenyl-silsesquioxane (POSS-10-4) were synthesized by copolymerization over the ansa-metallocene catalyst. The influence of the kind of silsesquioxane and of the copolymerization conditions on the reaction performance and on [...] Read more.

The copolymers of ethylene (E) with open-caged iso-butyl-substituted tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) and phenyl-substituted tetra-alkenyl-silsesquioxane (POSS-10-4) were synthesized by copolymerization over the ansa-metallocene catalyst. The influence of the kind of silsesquioxane and of the copolymerization conditions on the reaction performance and on the properties of the copolymers was studied. In the case of copolymerization of E/POSS-6-3, the positive comonomer effect was observed, which was associated with the influence of POSS-6-3 on transformation of the bimetallic ion pair to the active catalytic species. Functionality of silsesquioxanes and polymerization parameters affected the polyhedral oligomeric silsesquioxanes (POSS) contents in the copolymers which varied in the range of 1.33–7.43 wt %. Tri-alkenyl-silsesquioxanes were incorporated into the polymer chain as pendant groups while the tetra-alkenyl-silsesquioxane derivative could act as a cross-linking agent which was proved by the changes in the contents of unsaturated end groups, by the glass transition temperature values, and by the gel contents (up to 81.3% for E/POSS-10-4). Incorporation of multi-alkenyl-POSS into the polymer chain affected also the melting and crystallization behaviors. Full article

(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)

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15 pages, 2409 KiB

Open AccessArticle

RAFT Polymerization of Tert-Butyldimethylsilyl Methacrylate: Kinetic Study and Determination of Rate Coefficients

by Minh Ngoc Nguyen^1,*

, André Margaillan²

, Quang Trung Pham¹ and Christine Bressy^2,*

¹ Faculty of Chemistry, VNU University of Science, Hanoi, 19 Le Thanh Tong, Hoan Kiem, Hanoi 100000, Vietnam

² Laboratoire MAtériaux Polymères-Interfaces-Environment Marin (EA 4323 MAPIEM), Université de Toulon, CS 60584-83041 Toulon CEDEX 9, France

Polymers 2018, 10(2), 224; https://doi.org/10.3390/polym10020224 - 24 Feb 2018

Cited by 6 | Viewed by 7231

Abstract

Well-defined poly(tert-butyldimethylsilyl methacrylate)s (TBDMSMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) process using cyanoisopropyl dithiobenzoate (CPDB) as chain-transfer agents (CTA). The experimentally obtained molecular weight distributions are narrow and shift linearly with monomer conversion. Propagation rate coefficients (k [...] Read more.

Well-defined poly(tert-butyldimethylsilyl methacrylate)s (TBDMSMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) process using cyanoisopropyl dithiobenzoate (CPDB) as chain-transfer agents (CTA). The experimentally obtained molecular weight distributions are narrow and shift linearly with monomer conversion. Propagation rate coefficients (k_p) and termination rate coefficients (k_t) for free radical polymerization of TBDMSMA have been determined for a range of temperature between 50 and 80 °C using the pulsed laser polymerization-size-exclusion chromatography (PLP-SEC) method and the kinetic method via steady-state rate measurement, respectively. The CPDB-mediated RAFT polymerization of TBDMSMA has been subjected to a combined experimental and PREDICI modeling study at 70 °C. The rate coefficient for the addition reaction to RAFT agent (k_β1, k_β2) and to polymeric RAFT agent (k_β) is estimated to be approximately 1.8 × 10⁴ L·mol⁻¹·s⁻¹ and for the fragmentation reaction of intermediate RAFT radicals in the pre-equilibrium (k_-β1, k_-β2) and main equilibrium (k_-β) is close to 2.0 × 10⁻² s⁻¹. The transfer rate coefficient (k_tr) to cyanoisopropyl dithiobenzoate is found to be close to 9.0 × 10³ L·mol⁻¹·s⁻¹ and the chain-transfer constant (C_tr) for CPDB-mediated RAFT polymerization of TBDMSMA is about 9.3. Full article

(This article belongs to the Special Issue RAFT Living Radical Polymerization and Self-Assembly)

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16 pages, 2136 KiB

Open AccessArticle

Preparation and Characterization of Poly(ether-block-amide)/Polyethylene Glycol Composite Films with Temperature-Dependent Permeation

by Sarinthip Thanakkasaranee, Dowan Kim and Jongchul Seo^*

Department of Packaging, Yonsei University, 1 Yonseidae-gil, Wonju-si, Gangwon-do 26493, Korea

Polymers 2018, 10(2), 225; https://doi.org/10.3390/polym10020225 - 24 Feb 2018

Cited by 55 | Viewed by 8708

Abstract

A series of poly(ether-block-amide) (PEBAX)/polyethylene glycol (PEG) composite films (PBXPG) were prepared by solution casting technique. This study demonstrates how the incorporation of different molecular weight PEG into PEBAX can improve the as-prepared composite film performance in gas permeability as a function of [...] Read more.

A series of poly(ether-block-amide) (PEBAX)/polyethylene glycol (PEG) composite films (PBXPG) were prepared by solution casting technique. This study demonstrates how the incorporation of different molecular weight PEG into PEBAX can improve the as-prepared composite film performance in gas permeability as a function of temperature. Additionally, we investigated the effect of PEG with different molecular weights on gas transport properties, morphologies, thermal properties, and water sorption. The thermal stability of the composite films increased with increasing molecular weight of PEG, whereas the water sorption and total surface energy decreased. As the temperature increased from 10 to 80 °C, the low (L)-PBXPG and medium (M)-PBXPG films showed a trend similar to the pure PEBAX film. However, the high (H)-PBXPG film with relatively high molecular weight exhibited a distinct permeation jump in the phase change region of H-PEG, which is related to the temperature dependent changes in the morphology structure such as crystallinity and the chemical affinity between the polymer film and gas molecule. Based on these results, it can be expected that H-PBXPG composite films can be used as self-ventilating materials in microwave cooking. Full article

(This article belongs to the Special Issue Polymers for Packaging Applications)

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19 pages, 9678 KiB

Open AccessArticle

Woven Fabrics Made of Auxetic Plied Yarns

by Wing Sum Ng and Hong Hu^*

Institute of Textile and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China

Polymers 2018, 10(2), 226; https://doi.org/10.3390/polym10020226 - 24 Feb 2018

Cited by 67 | Viewed by 9081

Abstract

Auxetic plied yarns are specially constructed with two types of single yarns of different sizes and moduli. This paper investigates how to use these types of yarns to produce woven fabrics with auxetic effects. Four-ply auxetic yarns were first incorporated into a series [...] Read more.

Auxetic plied yarns are specially constructed with two types of single yarns of different sizes and moduli. This paper investigates how to use these types of yarns to produce woven fabrics with auxetic effects. Four-ply auxetic yarns were first incorporated into a series of woven fabrics with different design parameters to study their auxetic behavior and percent open area during extension. Effects of auxetic plied yarn arrangement, single component yarn properties, weft yarn type, and weave structure were then evaluated. Additional double helical yarn (DHY) and 6-ply auxetic yarn woven fabrics were also made for comparison. The results show that the alternative arrangement of S- and Z-twisted 4-ply auxetic yarns in a woven fabric can generate a higher negative Poisson’s ratio (NPR) of the fabric. While the higher single stiff yarn modulus of auxetic yarn can result in greater NPR behavior, finer soft auxetic yarn does not necessarily generate such an effect. Weft yarns with low modulus and short float over the 4-ply auxetic yarns in fabric structure are favorable for producing high NPR behavior. The weft cover factor greatly affects the variation of the percent open area of the 4-ply auxetic yarn fabrics during extension. When different kinds of helical auxetic yarns (HAYs) are made into fabrics, the fabric made of DHY does not have the highest NPR effect but it has the highest percent open area, which increases with increasing tensile strain. Full article

(This article belongs to the Special Issue Textile and Textile-Based Materials)

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Review

Jump to: Research

25 pages, 25711 KiB

Open AccessReview

Recent Achievements of Self-Healing Graphene/Polymer Composites

by Yongxu Du^†, Dong Li^†, Libin Liu^*

and Guangjie Gai

¹ School of Chemistry and Pharmaceutical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China

^† The two authors contribute to the paper equally.

Polymers 2018, 10(2), 114; https://doi.org/10.3390/polym10020114 - 25 Jan 2018

Cited by 76 | Viewed by 16973

Abstract

Self-healing materials have attracted much attention because that they possess the ability to increase the lifetime of materials and reduce the total cost of systems during the process of long-term use; incorporation of functional material enlarges their applications. Graphene, as a promising additive, [...] Read more.

Self-healing materials have attracted much attention because that they possess the ability to increase the lifetime of materials and reduce the total cost of systems during the process of long-term use; incorporation of functional material enlarges their applications. Graphene, as a promising additive, has received great attention due to its large specific surface area, ultrahigh conductivity, strong antioxidant characteristics, thermal stability, high thermal conductivity, and good mechanical properties. In this brief review, graphene-containing polymer composites with self-healing properties are summarized including their preparations, self-healing conditions, properties, and applications. In addition, future perspectives of graphene/polymer composites are briefly discussed. Full article

(This article belongs to the Special Issue Graphene-Polymer Composites)

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10 pages, 230 KiB

Open AccessReview

Recent Advances of Chitosan Applications in Plants

by Massimo Malerba¹ and Raffaella Cerana^2,*

¹ Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milan, Italy

² Dipartimento di Scienze dell’Ambiente e della Terra, Università degli Studi di Milano-Bicocca, 20126 Milan, Italy

Polymers 2018, 10(2), 118; https://doi.org/10.3390/polym10020118 - 26 Jan 2018

Cited by 190 | Viewed by 11806

Abstract

In recent years, the search for biological methods to avoid the application of chemical products in agriculture has led to investigating the use of biopolymers-based materials. Among the tested biomaterials, the best results were obtained from those based on the biopolymer chitosan (CHT). [...] Read more.

In recent years, the search for biological methods to avoid the application of chemical products in agriculture has led to investigating the use of biopolymers-based materials. Among the tested biomaterials, the best results were obtained from those based on the biopolymer chitosan (CHT). CHT, available in large quantities from the deacetylation of chitin, has multiple advantages: it is safe, inexpensive and can be easily associated with other compounds to achieve better performance. In this review, we have summarized the latest researches of the application of CHT on plant productivity, plant protection against the attack of pathogens and extension of the commercial life of detached fruits. Full article

(This article belongs to the Special Issue Advances in Chitin/Chitosan Characterization and Applications)

33 pages, 8550 KiB

Open AccessReview

Recent Advances of Plasmonic Organic Solar Cells: Photophysical Investigations

by Lin Feng¹, Mengsi Niu¹, Zhenchuan Wen¹ and Xiaotao Hao^1,2,*

¹ School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, Shandong, China

² ARC Center of Excellence in Exciton Sciences, School of Chemistry, the University of Melbourne, Parkville, Victoria 3010, Australia

Polymers 2018, 10(2), 123; https://doi.org/10.3390/polym10020123 - 26 Jan 2018

Cited by 85 | Viewed by 9863

Abstract

The surface plasmon resonance (SPR) of metallic nanomaterials, such as gold (Au) and silver (Ag), has been extensively exploited to improve the optical absorption, the charge carrier transport, and the ultimate device performances in organic photovoltaic cells (OPV). With the incorporation of diverse [...] Read more.

The surface plasmon resonance (SPR) of metallic nanomaterials, such as gold (Au) and silver (Ag), has been extensively exploited to improve the optical absorption, the charge carrier transport, and the ultimate device performances in organic photovoltaic cells (OPV). With the incorporation of diverse metallic nanostructures in active layers, buffer layers, electrodes, or between adjacent layers of OPVs, multiple plasmonic mechanisms may occur and need to be distinguished to better understand plasmonic enhancement. Steady-state photophysics is a powerful tool for unraveling the plasmonic nature and revealing plasmonic mechanisms such as the localized surface plasmon resonance (LSPR), the propagating plasmon-polariton (SPP), and the plasmon-gap mode. Furthermore, the charge transfer dynamics in the organic semiconductor materials can be elucidated from the transient photophysical investigations. In this review article, the basics of the plasmonic mechanisms and the related metallic nanostructures are briefly introduced. We then outline the recent advances of the plasmonic applications in OPVs emphasizing the linkage between the photophysical properties, the nanometallic geometries, and the photovoltaic performance of the OPV devices. Full article

(This article belongs to the Special Issue Polymer Solar Cells)

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15 pages, 2948 KiB

Open AccessReview

Host-Guest Chemistry in Layer-by-Layer Assemblies Containing Calix[n]arenes and Cucurbit[n]urils: A Review

by Uichi Akiba¹, Daichi Minaki² and Jun-ichi Anzai^2,*

¹ Graduate School of Engineering and Science, Akita University, 1-1 Tegata Gakuen-machi, Akita 010-8502, Japan

² Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan

Polymers 2018, 10(2), 130; https://doi.org/10.3390/polym10020130 - 29 Jan 2018

Cited by 14 | Viewed by 5095

Abstract

This review provides an overview of the synthesis of layer-by-layer (LbL) assemblies containing calix[n]arene (CA[n]) and cucurbit[n]uril (CB[n]) and their applications. LbL assemblies, such as thin films and microcapsules, containing selective binding sites have attracted [...] Read more.

This review provides an overview of the synthesis of layer-by-layer (LbL) assemblies containing calix[n]arene (CA[n]) and cucurbit[n]uril (CB[n]) and their applications. LbL assemblies, such as thin films and microcapsules, containing selective binding sites have attracted considerable attention because of their potential use in separation and purification, sensors for ions and molecules, and controlled release. CA[n]-containing LbL films have been prepared using sulfonated CA[n] and cationic polymers to construct chemical sensors and molecular containers. CA[n]-containing LbL films deposited on the surface of a porous support are useful as ion-selective membranes that exhibit selective permeability to monovalent ions over multivalent ions. CB[n]s have been used as molecular glues for the construction of LbL films and microcapsules by taking advantage of the strong affinity of CB[n]s to aromatic compounds. CB[n]s form a stable 1:1:1 ternary complex with electron-rich and electron-deficient molecules in LbL films to stabilize the assemblies. CB[n]-containing LbL films can also be deposited on the surfaces of micro templates and nanopore membranes to construct microcapsules for controlled release and nanochannels for selective ion transport, respectively. Full article

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8 pages, 2747 KiB

Open AccessReview

New Horizons in Cationic Photopolymerization

by Marco Sangermano^*

, Ignazio Roppolo

and Annalisa Chiappone

Politecnico di Torino, Dipartimento di Scienza Applicata e tecnologia, C.so Duca degli Abruzzi 24, 10129 Torino, Italy

Polymers 2018, 10(2), 136; https://doi.org/10.3390/polym10020136 - 31 Jan 2018

Cited by 102 | Viewed by 8441

Abstract

In this review, we report some recent advances and new horizons in UV-induced cationic photopolymerization. In particular, after a brief introduction on the discovery and affirmation of the cationic photopolymerization process, new efforts in the synthesis of cationic photoinitiators are reported. Subsequently, an [...] Read more.

In this review, we report some recent advances and new horizons in UV-induced cationic photopolymerization. In particular, after a brief introduction on the discovery and affirmation of the cationic photopolymerization process, new efforts in the synthesis of cationic photoinitiators are reported. Subsequently, an interesting and absolutely new application is reported, related to the combination of Radical-Induced Cationic Photopolymerization with Frontal Polymerization, achieving the cross-linking of epoxy composites. Full article

(This article belongs to the Special Issue Thermosets)

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26 pages, 2149 KiB

Open AccessReview

Fluorinated Polymers as Smart Materials for Advanced Biomedical Applications

by Vanessa F. Cardoso^1,2,*

, Daniela M. Correia^3,4, Clarisse Ribeiro^1,5

, Margarida M. Fernandes^1,5 and Senentxu Lanceros-Méndez^4,6

¹ Centro/Departamento de Física, Universidade do Minho, 4710-057 Braga, Portugal

² CMEMS-UMinho, Universidade do Minho, DEI, 4800-058 Guimaraes, Portugal

³ Departamento de Química e CQ-VR, Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal

⁴ BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain

⁵ CEB—Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal

⁶ IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain

Polymers 2018, 10(2), 161; https://doi.org/10.3390/polym10020161 - 8 Feb 2018

Cited by 235 | Viewed by 19799

Abstract

Fluorinated polymers constitute a unique class of materials that exhibit a combination of suitable properties for a wide range of applications, which mainly arise from their outstanding chemical resistance, thermal stability, low friction coefficients and electrical properties. Furthermore, those presenting stimuli-responsive properties have [...] Read more.

Fluorinated polymers constitute a unique class of materials that exhibit a combination of suitable properties for a wide range of applications, which mainly arise from their outstanding chemical resistance, thermal stability, low friction coefficients and electrical properties. Furthermore, those presenting stimuli-responsive properties have found widespread industrial and commercial applications, based on their ability to change in a controlled fashion one or more of their physicochemical properties, in response to single or multiple external stimuli such as light, temperature, electrical and magnetic fields, pH and/or biological signals. In particular, some fluorinated polymers have been intensively investigated and applied due to their piezoelectric, pyroelectric and ferroelectric properties in biomedical applications including controlled drug delivery systems, tissue engineering, microfluidic and artificial muscle actuators, among others. This review summarizes the main characteristics, microstructures and biomedical applications of electroactive fluorinated polymers. Full article

(This article belongs to the Special Issue Fluorinated Polymers)

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28 pages, 1703 KiB

Open AccessReview

Utilization of Slaughterhouse Waste in Value-Added Applications: Recent Advances in the Development of Wood Adhesives

by Birendra B. Adhikari, Michael Chae and David C. Bressler^*

Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life & Environmental Sciences, University of Alberta, Edmonton, AB T6G 2P5, Canada

Polymers 2018, 10(2), 176; https://doi.org/10.3390/polym10020176 - 11 Feb 2018

Cited by 107 | Viewed by 11679

Abstract

Globally, slaughterhouses generate large volumes of animal byproducts. While these byproducts are an important resource of industrial protein that could potentially be utilized in various value-added applications, they are currently either underutilized in high-value applications or being used for production of relatively low-value [...] Read more.

Globally, slaughterhouses generate large volumes of animal byproducts. While these byproducts are an important resource of industrial protein that could potentially be utilized in various value-added applications, they are currently either underutilized in high-value applications or being used for production of relatively low-value products such as animal feed and pet food. Furthermore, some of the byproducts of animal slaughtering cannot enter food and feed chains and thus their disposal possesses a serious environmental concern. An innovative utilization of the proteinaceous waste generated by slaughterhouses comprises of waste processing to extract proteins, which are then incorporated into industrial processes to produce value-added bio-based products. In this report, we review the current processes for extraction of protein from proteinaceous waste of slaughterhouses, and utilization of the recovered protein in the development of protein-based wood adhesives. Full article

(This article belongs to the Collection Polymeric Adhesives)

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24 pages, 3266 KiB

Open AccessReview

State of the Art in Dual-Curing Acrylate Systems

by Osman Konuray^1,*

, Xavier Fernández-Francos¹

, Xavier Ramis¹

and Àngels Serra²

¹ Thermodynamics Laboratory, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spain

² Department of Analytical and Organic Chemistry, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain

Polymers 2018, 10(2), 178; https://doi.org/10.3390/polym10020178 - 12 Feb 2018

Cited by 101 | Viewed by 20952

Abstract

Acrylate chemistry has found widespread use in dual-curing systems over the years. Acrylates are cheap, easily handled and versatile monomers that can undergo facile chain-wise or step-wise polymerization reactions that are mostly of the “click” nature. Their dual-curing processes yield two distinct and [...] Read more.

Acrylate chemistry has found widespread use in dual-curing systems over the years. Acrylates are cheap, easily handled and versatile monomers that can undergo facile chain-wise or step-wise polymerization reactions that are mostly of the “click” nature. Their dual-curing processes yield two distinct and temporally stable sets of material properties at each curing stage, thereby allowing process flexibility. The review begins with an introduction to acrylate-based click chemistries behind dual-curing systems and relevant reaction mechanisms. It then provides an overview of reaction combinations that can be encountered in these systems. It finishes with a survey of recent and breakthrough research in acrylate dual-curing materials for shape memory polymers, optical materials, photolithography, protective coatings, structured surface topologies, and holographic materials. Full article

(This article belongs to the Special Issue Thermosets)

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37 pages, 2090 KiB

Open AccessReview

Hydrogels-Assisted Cell Engraftment for Repairing the Stroke-Damaged Brain: Chimera or Reality

by Daniel González-Nieto^1,2,3,*, Laura Fernández-García¹, José Pérez-Rigueiro^1,3,4, Gustavo V. Guinea^1,3,4

and Fivos Panetsos^5,6

¹ Center for Biomedical Technology, Universidad Politécnica de Madrid, 28040 Madrid, Spain

² Departamento de Tecnología Fotónica y Bioingeniería, ETSI Telecomunicaciones, Universidad Politécnica de Madrid, 28040 Madrid, Spain

³ Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), 28040 Madrid, Spain

⁴ Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid 28040 Madrid, Spain

⁵ Neurocomputing and Neurorobotics Research Group: Faculty of Biology and Faculty of Optics, Universidad Complutense de Madrid, 28040 Madrid, Spain

⁶ Instituto de Investigación Sanitaria, Hospital Clínico San Carlos Madrid, IdISSC, 28040 Madrid, Spain

Polymers 2018, 10(2), 184; https://doi.org/10.3390/polym10020184 - 13 Feb 2018

Cited by 31 | Viewed by 8519

Abstract

The use of advanced biomaterials as a structural and functional support for stem cells-based therapeutic implants has boosted the development of tissue engineering applications in multiple clinical fields. In relation to neurological disorders, we are still far from the clinical reality of restoring [...] Read more.

The use of advanced biomaterials as a structural and functional support for stem cells-based therapeutic implants has boosted the development of tissue engineering applications in multiple clinical fields. In relation to neurological disorders, we are still far from the clinical reality of restoring normal brain function in neurodegenerative diseases and cerebrovascular disorders. Hydrogel polymers show unique mechanical stiffness properties in the range of living soft tissues such as nervous tissue. Furthermore, the use of these polymers drastically enhances the engraftment of stem cells as well as their capacity to produce and deliver neuroprotective and neuroregenerative factors in the host tissue. Along this article, we review past and current trends in experimental and translational research to understand the opportunities, benefits, and types of tentative hydrogel-based applications for the treatment of cerebral disorders. Although the use of hydrogels for brain disorders has been restricted to the experimental area, the current level of knowledge anticipates an intense development of this field to reach clinics in forthcoming years. Full article

(This article belongs to the Special Issue Hydrogels in Tissue Engineering and Regenerative Medicine)

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27 pages, 3155 KiB

Open AccessReview

Polymer@gold Nanoparticles Prepared via RAFT Polymerization for Opto-Biodetection

by Sónia O. Pereira^*

, Ana Barros-Timmons and Tito Trindade

Department of Chemistry, CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal

Polymers 2018, 10(2), 189; https://doi.org/10.3390/polym10020189 - 14 Feb 2018

Cited by 28 | Viewed by 10761

Abstract

Colloidal gold nanoparticles (Au NPs) have been used in several biological applications, which include the exploitation of size- and shape-dependent Localized Surface Plasmon Resonance (LSPR) in biosensing devices. In order to obtain functional and stable Au NPs in a physiological medium, surface modification [...] Read more.

Colloidal gold nanoparticles (Au NPs) have been used in several biological applications, which include the exploitation of size- and shape-dependent Localized Surface Plasmon Resonance (LSPR) in biosensing devices. In order to obtain functional and stable Au NPs in a physiological medium, surface modification and functionalization are crucial steps in these endeavors. Reversible addition-fragmentation chain transfer (RAFT) polymerization meets this need offering the possibility of control over the composition and architecture of polymeric shells coating Au NPs. Furthermore, playing with a careful choice of monomers, RAFT polymerization allows the possibility to design a polymer shell with the desired functional groups aiming at Au based nanocomposites suitable for biorecognition and biotargeting. This review provides important aspects concerning the synthesis and optical properties of Au NPs as well as concepts of RAFT polymerization. Understanding these concepts is crucial to appreciate the chemical strategies available towards RAFT-polymer coated Au core-shell nanostructures, which are here reviewed. Finally, examples of applications in opto-biodetection devices are provided and the potential of responsive “smart” nanomaterials based on such structures can be applied to other biological applications. Full article

(This article belongs to the Special Issue Polymeric Materials for Optical Applications)

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25 pages, 995 KiB

Open AccessReview

Cosmetics and Cosmeceutical Applications of Chitin, Chitosan and Their Derivatives

by Inmaculada Aranaz^1,2,*, Niuris Acosta^1,2

, Concepción Civera¹, Begoña Elorza¹, Javier Mingo^1,2, Carolina Castro^1,2, María De los Llanos Gandía^1,2

and Angeles Heras Caballero^1,2,*

¹ Department of Chemistry in Pharmaceutical Sciences, Pharmacy Faculty, Complutense University, Plaza de Ramón y Cajal, s/n, 28040 Madrid, Spain

² Bifunctional Studies Institute, Complutense University, Paseo Juan XXIII, 1, 28040 Madrid, Spain

Polymers 2018, 10(2), 213; https://doi.org/10.3390/polym10020213 - 22 Feb 2018

Cited by 323 | Viewed by 23240

Abstract

Marine resources are well recognized for their biologically active substances with great potential applications in the cosmeceutical industry. Among the different compounds with a marine origin, chitin and its deacetylated derivative—chitosan—are of great interest to the cosmeceutical industry due to their unique biological [...] Read more.

Marine resources are well recognized for their biologically active substances with great potential applications in the cosmeceutical industry. Among the different compounds with a marine origin, chitin and its deacetylated derivative—chitosan—are of great interest to the cosmeceutical industry due to their unique biological and technological properties. In this review, we explore the different functional roles of chitosan as a skin care and hair care ingredient, as an oral hygiene agent and as a carrier for active compounds, among others. The importance of the physico-chemical properties of the polymer in its use in cosmetics are particularly highlighted. Moreover, we analyse the market perspectives of this polymer and the presence in the market of chitosan-based products. Full article

(This article belongs to the Special Issue Advances in Chitin/Chitosan Characterization and Applications)

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22 pages, 2783 KiB

Open AccessReview

Recent Developments in Graphene/Polymer Nanocomposites for Application in Polymer Solar Cells

by Ana Maria Díez-Pascual^1,*

, José Antonio Luceño Sánchez¹

, Rafael Peña Capilla² and Pilar García Díaz²

¹ Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, Faculty of Biology, Environmental Sciences and Chemistry, Alcalá University, 28871 Madrid, Spain

² Department of Signal Theory and Communication, Polytechnic High School, Alcalá University, 28871 Madrid, Spain

Polymers 2018, 10(2), 217; https://doi.org/10.3390/polym10020217 - 22 Feb 2018

Cited by 124 | Viewed by 10792

Abstract

Graphene (G) and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO) have enormous potential for energy applications owing to their 2D structure, large specific surface area, high electrical and thermal conductivity, optical transparency, and huge mechanical strength combined with inherent flexibility. [...] Read more.

Graphene (G) and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO) have enormous potential for energy applications owing to their 2D structure, large specific surface area, high electrical and thermal conductivity, optical transparency, and huge mechanical strength combined with inherent flexibility. The combination of G-based materials with polymers leads to new nanocomposites with enhanced structural and functional properties due to synergistic effects. This review briefly summarizes recent progress in the development of G/polymer nanocomposites for use in polymer solar cells (PSCs). These nanocomposites have been explored as transparent conducting electrodes (TCEs), active layers (ALs) and interfacial layers (IFLs) of PSCs. Photovoltaic parameters, such as the open-circuit voltage (V_oc), short-circuit current density (J_sc), fill factor (FF) and power-conversion efficiency (PCE) are compared for different device structures. Finally, future perspectives are discussed. Full article

(This article belongs to the Special Issue Nanoparticle-Reinforced Polymers)

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