Polymers

Editorial

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14 pages, 167 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Polymers in 2017

by Polymers Editorial Office

MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland

Polymers 2018, 10(1), 69; https://doi.org/10.3390/polym10010069 - 13 Jan 2018

Viewed by 3377

Abstract

Peer review is an essential part in the publication process, ensuring that Polymers maintains high quality standards for its published papers.[...] Full article

Research

Jump to: Editorial, Review

17 pages, 4232 KiB

Open AccessArticle

Silica Modified by Alcohol Polyoxyethylene Ether and Silane Coupling Agent Together to Achieve High Performance Rubber Composites Using the Latex Compounding Method

by Junchi Zheng¹, Xin Ye^1,2, Dongli Han¹, Suhe Zhao^1,2, Xiaohui Wu¹, Youping Wu^1,2, Dong Dong³, Yiqing Wang^1,2,* and Liqun Zhang^1,2,*

¹ Engineering Research Center of Elastomer Materials on Energy Conservation and Resources, Ministry of Education, Beijing 100029, China

² State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, P.O. Box 57, Beisanhuan East Road, Beijing 100029, China

³ Red Avenue New Materials Group Co., Ltd., Shanghai 200120, China

Polymers 2018, 10(1), 1; https://doi.org/10.3390/polym10010001 - 21 Dec 2017

Cited by 49 | Viewed by 9013

Abstract

The study of preparing silica/rubber composites used in tires with low rolling resistance in an energy-saving method is fast-growing. In this study, a novel strategy is proposed, in which silica was modified by combing alcohol polyoxyethylene ether (AEO) and 3-mercaptopropyltriethoxysilane (K-MEPTS) for preparing [...] Read more.

The study of preparing silica/rubber composites used in tires with low rolling resistance in an energy-saving method is fast-growing. In this study, a novel strategy is proposed, in which silica was modified by combing alcohol polyoxyethylene ether (AEO) and 3-mercaptopropyltriethoxysilane (K-MEPTS) for preparing silica/natural rubber (NR) master batches. A thermal gravimetric analyzer and Raman spectroscopy results indicated that both AEO and K-MEPTS could be grafted on to the silica surface, and AEO has a chance to shield the mercaptopropyl group on K-MEPTS. Silica modified by AEO and K-MEPTS together was completely co-coagulated with the rubber in preparing silica/NR composites using the latex compounding method with the help of the interaction between AEO and K-MEPTS. The performance of composites prepared by silica/NR master batches was investigated by a rubber process analyzer (RPA), transmission electron microscopy (TEM) and a tensile tester. These results demonstrate that AEO forms a physical interface between silica and rubber, resulting in good silica dispersion in the matrix. K-MEPTS forms a chemical interface between silica and rubber, enhancing the reinforcing effect of silica and reducing the mutual friction between silica particles. In summary, using a proper combination of AEO and K-MEPTS is a user-friendly approach for preparing silica/NR composites with excellent performance. Full article

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

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13 pages, 4526 KiB

Open AccessArticle

Titanium(III, IV)-Containing Catalytic Systems for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solventless Processing—Impact of Oxidation States of Transition Metal

by Vladislav A. Tuskaev^1,*, Svetlana C. Gagieva¹, Dmitrii A. Kurmaev¹, Nikolay A. Kolosov¹, Elena S. Mikhaylik^2,3, Evgenii K. Golubev^2,3, Alexander I. Sizov¹, Sergey V. Zubkevich¹, Viktor G. Vasil’ev², Galina G. Nikiforova², Mikhail I. Buzin², Olga A. Serenko² and Boris M. Bulychev¹

¹ Department of Chemistry, M. V. Lomonosov Moscow State University, 1 Leninskie Gory, 119992 Moscow, Russia

² A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 ul. Vavilova, 119991 Moscow, Russia

³ Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences, Profsoyuznaya Str., 70; 117393 Moscow, Russia

Polymers 2018, 10(1), 2; https://doi.org/10.3390/polym10010002 - 21 Dec 2017

Cited by 15 | Viewed by 6337

Abstract

Catalytic systems containing TiCl₄ or TiCl₃, THF, organomagnesium (n-Bu₂Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8–7.8) [...] Read more.

Catalytic systems containing TiCl₄ or TiCl₃, THF, organomagnesium (n-Bu₂Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8–7.8) × 10⁶ Da and desirable morphology, suitable for modern methods of polymer processing—the solvent-free solid-state processing of superhigh-strength (tensile strength up to 2.1 GPa) and high-modulus (elastic modulus up to 125 GPa) oriented films and film tapes. The impacts of a THF additive, the oxidation state of the titanium atom, and the composition and nature of the nontransition organometallic compounds on the formation of catalytic systems for UHMWPE production were evaluated. The results indicate the suitability of individual titanium chloride tetrahydrofuran complex application for the formation of THF-containing catalytic systems. This approach also results in a significant increase in the system catalytic activity and mechanical properties of UHMWPE. The catalysts based on Ti(III) were inferior to systems containing Ti(IV) in productivity but were markedly superior in the mechanical properties of UHMWPE. Full article

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

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15 pages, 4092 KiB

Open AccessArticle

Manufacturing and Characterization of Toughened Poly(lactic acid) (PLA) Formulations by Ternary Blends with Biopolyesters

by María Jesús García-Campo¹, Teodomiro Boronat², Luis Quiles-Carrillo¹

, Rafael Balart^1,*

and Nestor Montanes¹

¹ Materials Science Division, Technological Institute of Materials, Universitat Politècnica de València, 03801 Alcoy, Alicante, Spain

² Manufacturing Engineering Division, Technological Institute of Materials, Universitat Politècnica de València, 03801 Alcoy, Alicante, Spain

Polymers 2018, 10(1), 3; https://doi.org/10.3390/polym10010003 - 21 Dec 2017

Cited by 34 | Viewed by 6933

Abstract

Ternary blends with a constant poly(lactic acid) (PLA) content (60 wt %) and varying amounts of poly(3-hydroxybutyrate) (PHB) and poly(ε-caprolactone) (PCL) were manufactured by one step melt blending process followed by injection moulding, with the main aim of improving the low intrinsic toughness [...] Read more.

Ternary blends with a constant poly(lactic acid) (PLA) content (60 wt %) and varying amounts of poly(3-hydroxybutyrate) (PHB) and poly(ε-caprolactone) (PCL) were manufactured by one step melt blending process followed by injection moulding, with the main aim of improving the low intrinsic toughness of PLA. Mechanical properties were obtained from tensile and Charpy impact tests. The miscibility and morphology of the system was studied by thermal analysis and field emission scanning electron microscopy (FESEM). The obtained results showed a clear phase separation, thus indicating poor miscibility between these three biopolyesters, i.e., PLA, the continuous component with dispersed PHB and PCL domains in the form of different sphere size. Nevertheless, the high fragility of PLA was remarkably reduced, as detected by the Charpy impact test. In accordance with the decrease in brittleness, a remarkable increase in elongation at break is achieved, with increasing PCL load due to its flexibility; in addition, increasing PCL load provides thermal stability at high temperatures. Thus, tailored materials can be manufactured by melt blending PLA, PHB, and PCL in different percentages to offer a wide range of biodegradable polymer blends. Full article

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

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13 pages, 3659 KiB

Open AccessArticle

Passivating ZnO Surface States by C60 Pyrrolidine Tris-Acid for Hybrid Solar Cells Based on Poly(3-hexylthiophene)/ZnO Nanorod Arrays

by Peng Zhong^1,2, Xiaohua Ma^1,2,* and He Xi^1,2

¹ School of Advanced Materials and Nanotechnology, Xidian University, 266 Xinglong Section of Xifeng Road, Xi’an 710126, Shaanxi, China

² Key Labof Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi’an 710071, Shaanxi, China

Polymers 2018, 10(1), 4; https://doi.org/10.3390/polym10010004 - 21 Dec 2017

Cited by 8 | Viewed by 6017

Abstract

Construction of ordered electron acceptors is a feasible way to solve the issue of phase separation in polymer solar cells by using vertically-aligned ZnO nanorod arrays (NRAs). However, the inert charge transfer between conducting polymer and ZnO limits the performance enhancement of this [...] Read more.

Construction of ordered electron acceptors is a feasible way to solve the issue of phase separation in polymer solar cells by using vertically-aligned ZnO nanorod arrays (NRAs). However, the inert charge transfer between conducting polymer and ZnO limits the performance enhancement of this type of hybrid solar cells. In this work, a fullerene derivative named C60 pyrrolidine tris-acid is used to modify the interface of ZnO/poly(3-hexylthiophene) (P3HT). Results indicate that the C60 modification passivates the surface defects of ZnO and improves its intrinsic fluorescence. The quenching efficiency of P3HT photoluminescence is enhanced upon C60 functionalization, suggesting a more efficient charge transfer occurs across the modified P3HT/ZnO interface. Furthermore, the fullerene modified hybrid solar cell based on P3HT/ZnO NRAs displays substantially-enhanced performance as compared to the unmodified one and the devices with other modifiers, which is contributed to retarded recombination and enhanced exciton separation as evidenced by electrochemical impedance spectra. Therefore, fullerene passivation is a promising method to ameliorate the connection between conjugated polymers and metal oxides, and is applicable in diverse areas, such as solar cells, transistors, and light-emitting dioxides. Full article

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

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11 pages, 4364 KiB

Open AccessArticle

Modeling of Structure Effect for Ferroelectric Capacitor Based on Poly(vinylidene fluoride-trifluoroethylene) Ultrathin Films

by Long Li^1,2, Xiuli Zhang^1,3,*, Hongzhen Chen³, Xiaohui Sun¹, Haidong Yuan³ and Haisheng Xu^4,5,*

¹ School of Mathematics, Physics and Statistics, Shanghai University of Engineering Science, Shanghai 201620, China

² School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China

³ Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong, China

⁴ Department of Physics, East China University of Science and Technology, Shanghai 200237, China

⁵ Kunshan Hisense Electronics Co., Ltd., Kunshan 215300, China

Polymers 2018, 10(1), 6; https://doi.org/10.3390/polym10010006 - 22 Dec 2017

Cited by 8 | Viewed by 4566

Abstract

The characteristics of ferroelectric capacitors with poly(vinylidene fluoride-trifluoroethlene) (P(VDF-TrFE)) films have been studied at different structures of cell electrodes. It is suggested that the effect of electrode structures could induce changes of performance. Remarkably, cells with line electrodes display a better polarization and [...] Read more.

The characteristics of ferroelectric capacitors with poly(vinylidene fluoride-trifluoroethlene) (P(VDF-TrFE)) films have been studied at different structures of cell electrodes. It is suggested that the effect of electrode structures could induce changes of performance. Remarkably, cells with line electrodes display a better polarization and fatigue resistance than those with flat electrodes. For P(VDF-TrFE) ultrathin films with different electrode structures, the models of charge compensation mechanism for depolarization field and domain fatigue decomposition are used to explain the effect of electrode structure. Furthermore, the driving voltage based on normal speed-functionality is designed, and the testing results show that the line electrode structure could induce a robust switching, which is determined by the free charges concentration in active layer. These findings provide an effective route to design the optimum structure for a ferroelectric capacitor based on P(VDF-TrFE) copolymer ultrathin film. Full article

(This article belongs to the Special Issue Fluorinated Polymers)

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18 pages, 5917 KiB

Open AccessArticle

Crystallization and Stereocomplexation of PLA-mb-PBS Multi-Block Copolymers

by Rosa M. D’Ambrosio¹, Rose Mary Michell¹, Rosica Mincheva², Rebeca Hernández³, Carmen Mijangos³, Philippe Dubois²

and Alejandro J. Müller^1,4,5,*

¹ Grupo de Polímeros USB, Departamento de Ciencia de los Materiales, Universidad Simón Bolívar, Apartado 89000, 1080-A Caracas, Venezuela

² Laboratory of Polymeric and Composite Materials, Center of Innovation and Research in Materials & Polymers (CIRMAP), University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium

³ Instituto de Ciencia y Tecnología de Polímeros, CSIC, c/Juan de la Cierva 3, 28006 Madrid, Spain

⁴ Polymat and Polymer Science and Technology Department, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel de Lardizabal 3, 20018 Donostia-San Sebastián, Spain

⁵ Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain

Polymers 2018, 10(1), 8; https://doi.org/10.3390/polym10010008 - 22 Dec 2017

Cited by 16 | Viewed by 7627

Abstract

The crystallization and morphology of PLA-mb-PBS copolymers and their corresponding stereocomplexes were studied. The effect of flexible blocks (i.e., polybutylene succinate, PBS) on the crystallization of the copolymers and stereocomplex formation were investigated using polarized light optical microscopy (PLOM), differential scanning [...] Read more.

The crystallization and morphology of PLA-mb-PBS copolymers and their corresponding stereocomplexes were studied. The effect of flexible blocks (i.e., polybutylene succinate, PBS) on the crystallization of the copolymers and stereocomplex formation were investigated using polarized light optical microscopy (PLOM), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and carbon-13 nuclear magnetic resonance spectroscopy (¹³C-NMR). The PLA and PBS multiple blocks were miscible in the melt and in the glassy state. When the PLA-mb-PBS copolymers are cooled from the melt, the PLA component crystallizes first creating superstructures, such as spherulites or axialites, which constitute a template within which the PBS component has to crystallize when the sample is further cooled down. The Avrami theory was able to fit the overall crystallization kinetics of both semi-crystalline components, and the n values for both blocks in all the samples had a correspondence with the superstructural morphology observed by PLOM. Solution mixtures of PLLA-mb-PBS and PLDA-mb-PBS copolymers were prepared, as well as copolymer/homopolymer blends with the aim to study the stereocomplexation of PLLA and PDLA chain segments. A lower amount of stereocomplex formation was observed in copolymer mixtures as compared to neat L₁₀₀/D₁₀₀ stereocomplexes. The results show that PBS chain segments perturb the formation of stereocomplexes and this perturbation increases with the amount of PBS in the samples. However, when relatively low amounts of PBS in the copolymer blends are present, the rate of stereocomplex formation is enhanced. This effect dissappears when higher amounts of PBS are present. The stereocomplexation was confirmed by FTIR and solid state ¹³C-NMR analyses. Full article

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

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13 pages, 3838 KiB

Open AccessArticle

Combination of Magnetic Lignocellulosic Particles, High-Density Polyethylene, and Carbon Black for the Construction of Composites with Tunable Functionalities

by Jingfa Zhang¹, Haowei Wang¹, Haigang Wang^1,*, Dan Xing², Zhijun Zhang¹ and Qingwen Wang^3,*

¹ Key Laboratory of Bio-Based Materials Science and Technology (Ministry of Education), Northeast Forestry University, Harbin 150040, China

² Beiguo Intellectual Property Service Co., Ltd., Harbin 150040, China

³ College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China

Polymers 2018, 10(1), 9; https://doi.org/10.3390/polym10010009 - 22 Dec 2017

Cited by 12 | Viewed by 4644

Abstract

Biocomposites with unique functionalities for tailored applications are promising products for a sustainable future. In this work, a process concept of forming functional composites by combining of high-density polyethylene, carbon black, and magnetic lignocellulosic particles (wood flour) was demonstrated. The impacts of process [...] Read more.

Biocomposites with unique functionalities for tailored applications are promising products for a sustainable future. In this work, a process concept of forming functional composites by combining of high-density polyethylene, carbon black, and magnetic lignocellulosic particles (wood flour) was demonstrated. The impacts of process parameters on morphologies, crystalline phase, and magnetic intensity of wood flour were identified. Magnetic, antistatic and mechanical properties of biocomposites were also evaluated. Lignocellulosic particles were encapsulated with magnetic nanoparticles, and the resulting composites exhibited tunable magnetic and antistatic properties. A noticeable feature is that magnetic nanoparticles were uniformly distributed in the matrices as a result of anchorage to lignocellulosic particles. Magnetic lignocellulosic particles and polymer resin had good compatibility. The resulting composites provided another opportunity for shielding materials, which could reduce the radiation in the living environment. These findings could provide a tunable strategy of the tailored use of lignocellulose-based composites in functional applications. Full article

(This article belongs to the Collection Polysaccharides)

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15 pages, 3567 KiB

Open AccessArticle

Magnetic Nanoparticles Coated with a Thermosensitive Polymer with Hyperthermia Properties

by Felisa Reyes-Ortega^1,*

, Ángel V. Delgado¹

, Elena K. Schneider²

, B. L. Checa Fernández¹

and G. R. Iglesias¹

¹ Department of Applied Physics, University of Granada, Av. Fuentenueva s/n, 18071 Granada, Spain

² Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences; Monash University, Parkville, Victoria 3052, Australia

Polymers 2018, 10(1), 10; https://doi.org/10.3390/polym10010010 - 22 Dec 2017

Cited by 65 | Viewed by 9614

Abstract

Magnetic nanoparticles (MNPs) have been widely used to increase the efficacy of chemotherapeutics, largely through passive accumulation provided by the enhanced permeability and retention effect. Their incorporation into biopolymer coatings enables the preparation of magnetic field-responsive, biocompatible nanoparticles that are well dispersed in [...] Read more.

Magnetic nanoparticles (MNPs) have been widely used to increase the efficacy of chemotherapeutics, largely through passive accumulation provided by the enhanced permeability and retention effect. Their incorporation into biopolymer coatings enables the preparation of magnetic field-responsive, biocompatible nanoparticles that are well dispersed in aqueous media. Here we describe a synthetic route to prepare functionalized, stable magnetite nanoparticles (MNPs) coated with a temperature-responsive polymer, by means of the hydrothermal method combined with an oil/water (o/w) emulsion process. The effects of both pH and temperature on the electrophoretic mobility and surface charge of these MNPs are investigated. The magnetite/polymer composition of these systems is detected by Fourier Transform Infrared Spectroscopy (FTIR) and quantified by thermogravimetric analysis. The therapeutic possibilities of the designed nanostructures as effective heating agents for magnetic hyperthermia are demonstrated, and specific absorption rates as high as 150 W/g, with 20 mT magnetic field and 205 kHz frequency, are obtained. This magnetic heating response could provide a promising nanoparticle system for combined diagnostics and cancer therapy. Full article

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

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14 pages, 5749 KiB

Open AccessArticle

Investigation of Conical Spinneret in Generating More Dense and Compact Electrospun Nanofibers

by Aya Hamed^1,2, Nader Shehata^1,2,3,4,*

and Mohammad Elosairy¹

¹ Department of Engineering Mathematics and Physics, Faculty of Engineering, Alexandria University, Elhadara, Alexandria 21544, Egypt

² Center of Smart Nanotechnology and Photonics (CSNP), Smart Critical Infrastructure (SmartCI) Research Center, Alexandria University, Elhadara, Alexandria 21544, Egypt

³ USTAR Bio Innovations Center, Faculty of Science, Utah State University, Logan, UT 84341, USA

⁴ Department of Physics, Kuwait College of Science and Technology (KCST), Doha Road, 7th Ring Road, P.O. Box 27235, Safat 13133, Kuwait

Polymers 2018, 10(1), 12; https://doi.org/10.3390/polym10010012 - 22 Dec 2017

Cited by 14 | Viewed by 4841

Abstract

Electrospinning is an important, widely used process to generate nanofibers. However, there is still an open window for different designs of both spinneret and collector electrodes to be investigated. This paper introduces the impact of new design of conical spinneret electrode on the [...] Read more.

Electrospinning is an important, widely used process to generate nanofibers. However, there is still an open window for different designs of both spinneret and collector electrodes to be investigated. This paper introduces the impact of new design of conical spinneret electrode on the generated electrospun nanofibers. In this work, the conical feeder is used to generate electrospun Poly(vinyl alcohol) (PVA) nanofibers, and being compared to the traditional needle feeder at the same processing conditions. The jet’s mechanism is simulated using discrete bead model along with estimated calculations of both deposition area and fiber radius. The electric field distribution that is around the charged cone is analyzed. Based on both theoretical modeling and experimental measurements, a comparison of mean diameter, deposited area, and the thickness of generated nanofibers is presented related to both conical and needle electrodes. Conical feeder shows clearly compact nanofibers mat in terms of deposition area (spherical deposition of diameter ~6 cm) up to half-area of needle deposited nanofibers with high fiber density for the same time of the process. Moreover, the conical electrode is found to have privilege in terms of productivity rate and operation time. This study can be useful in generating localized nanofibers within different applications, such as biomedical tissue scaffolds, textile, and sensors. Full article

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

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10 pages, 3578 KiB

Open AccessArticle

A pH-Sensing Film from Tamarind Seed Polysaccharide with Litmus Lichen Extract as an Indicator

by Tieqiang Liang^1,2 and Lijuan Wang^1,2,*

¹ Key Laboratory of Bio-Based Materials Science and Technology of Ministry of Education, Northeast Forestry University, Harbin 150040, China

² Research Center of Wood Bionic Intelligent Science, Northeast Forestry University, Harbin 150040, China

Polymers 2018, 10(1), 13; https://doi.org/10.3390/polym10010013 - 22 Dec 2017

Cited by 50 | Viewed by 8125

Abstract

A new pH-sensing film was developed by using tamarind seed polysaccharide (TSP) and natural dye extracted from litmus lichen (LLE). The addition of LLE from 0 to 2.5% decreased the tensile strength and elongation at break from 30.20 to 29.97 MPa and 69.73% [...] Read more.

A new pH-sensing film was developed by using tamarind seed polysaccharide (TSP) and natural dye extracted from litmus lichen (LLE). The addition of LLE from 0 to 2.5% decreased the tensile strength and elongation at break from 30.20 to 29.97 MPa and 69.73% to 60.13%, respectively, but increased the water vapor permeability from 0.399 × 10⁻⁹ to 0.434 × 10⁻⁹ g·s⁻¹·m⁻¹·Pa⁻¹. The UV–Vis spectra of the litmus lichen extract (LLE) in the pH range of 4–10 showed that the color clearly changed from orange to blue. The characterization results showed that TSP interacted with LLE through hydrogen bonds. The color of the film varied from orange (pH 4.0) to blue-violet (pH 10.0). The full cream milk spoilage test indicated that the film is suitable for application in full cream milk spoilage detection. The developed pH-sensing film could be used as a promising diagnostic tool for the detection of food spoilage. Full article

(This article belongs to the Collection Polysaccharides)

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13 pages, 5356 KiB

Open AccessArticle

PLMA-b-POEGMA Amphiphilic Block Copolymers as Nanocarriers for the Encapsulation of Magnetic Nanoparticles and Indomethacin

by Athanasios Skandalis¹, Andreas Sergides^2,3,4, Aristides Bakandritsos⁵ and Stergios Pispas^1,*

¹ Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece

² Department of Pharmacy, University of Patras, 26504 Rio Patras, Greece

³ Department of Materials Science, University of Patras, 25604 Rio Patras, Greece

⁴ UCL Healthcare Biomagnetic and Nanomaterials Laboratories, Department of Physics and Astronomy, The Royal Institution of Great Britain, 21 Albemarle street, London W1S 4BS, UK

⁵ Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic

Polymers 2018, 10(1), 14; https://doi.org/10.3390/polym10010014 - 23 Dec 2017

Cited by 15 | Viewed by 6333

Abstract

We report here on the utilization of poly(lauryl methacrylate)-b-poly(oligo ethylene glycol methacrylate) (PLMA-b-POEGMA) amphiphilic block copolymers, which form compound micelles in aqueous solutions, as nanocarriers for the encapsulation of either magnetic iron oxide nanoparticles or iron oxide nanoparticles, and [...] Read more.

We report here on the utilization of poly(lauryl methacrylate)-b-poly(oligo ethylene glycol methacrylate) (PLMA-b-POEGMA) amphiphilic block copolymers, which form compound micelles in aqueous solutions, as nanocarriers for the encapsulation of either magnetic iron oxide nanoparticles or iron oxide nanoparticles, and the model hydrophobic drug indomethacin in the their hydrophobic core. The mixed nanostructures were characterized using dynamic light scattering (DLS) and transmission electron microscopy (TEM) in terms of their structure and solution properties. Magnetophoresis experiments showed that the mixed solutions maintain the magnetic properties of the initial iron oxide nanoparticles. Results indicate that the cumulative hydrophilic/hydrophobic balance of all components determines the colloidal stability of the nanosystems. The effect of salt and bovine serum albumin (BSA) protein concentration on the structure of the mixed nanostructures was also investigated. Disintegration of the mixed nanostructures was observed in both cases, showing the importance of these parameters in the structure formation and stability of such complex mixed nanosystems. Full article

(This article belongs to the Special Issue Polymer Micelles)

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13 pages, 3135 KiB

Open AccessArticle

Preparation of Antibacterial Cellulose Paper Using Layer-by-Layer Assembly for Cooked Beef Preservation at Ambient Temperature

by Hui Li¹, Rongqi Cui¹, Lincai Peng², Shengbao Cai¹, Pan Li¹ and Tianqing Lan^1,*

¹ Research Institute of Food Safety, Kunming University of Science and Technology, Kunming 650600, China

² Faculty of Chemical Engineering, Kunming University of Science and Technology, Kunming 650500, China

Polymers 2018, 10(1), 15; https://doi.org/10.3390/polym10010015 - 23 Dec 2017

Cited by 21 | Viewed by 6091

Abstract

Positively-charged ε-poly(l-lysine) (ε-PL) and negatively-charged carboxymethyl cellulose (CMC) were alternately deposited on a cellulose paper surface by the layer-by-layer (LBL) assembly technique. The formation of ε-PL/CMC multilayers was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), and zeta [...] Read more.

Positively-charged ε-poly(l-lysine) (ε-PL) and negatively-charged carboxymethyl cellulose (CMC) were alternately deposited on a cellulose paper surface by the layer-by-layer (LBL) assembly technique. The formation of ε-PL/CMC multilayers was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), and zeta potential measurement. The morphologies of the multilayer-modified cellulose paper were observed by scanning electron microscopy (SEM). The ε-PL/CMC multilayers effectively improved not only the antibacterial activity of cellulose paper against both Escherichia coli and Staphylococcus aureus, but also the cellulose paper tensile strength property. Cellulose paper modified with a (ε-PL/CMC)_4.5 multilayer exhibited the strongest antibacterial activity, selected for preserving cooked beef for nine days at ambient temperature, could extend the shelf-life of beef for about three days compared with common commercial PE films. The prepared antibacterial paper did not show any evidence of the cytotoxic effect since it could not increase the cytoplasmic lactate dehydrogenase release from L-929 fibroblast cells in contact with the antibacterial paper, suggesting the possibility of utilization in food packaging field. Full article

(This article belongs to the Collection Polysaccharides)

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17 pages, 3627 KiB

Open AccessArticle

New Development of Membrane Base Optoelectronic Devices

by Leon Hamui^1,*, María Elena Sánchez-Vergara^1,*, Rocío Sánchez-Ruiz¹, Diego Ruanova-Ferreiro¹, Ricardo Ballinas Indili² and Cecilio Álvarez-Toledano²

¹ Facultad de Ingeniería, Universidad Anáhuac México, Av. Universidad Anáhuac 46, Col. Lomas Anáhuac, Huixquilucan C.P. 52786, Estado de México, México

² Instituto de Química, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, Coyoacán, México D.F. 04510, México

Polymers 2018, 10(1), 16; https://doi.org/10.3390/polym10010016 - 23 Dec 2017

Cited by 9 | Viewed by 5445

Abstract

It is known that one factor that affects the operation of optoelectronic devices is the effective protection of the semiconductor materials against environmental conditions. The permeation of atmospheric oxygen and water molecules into the device structure induces degradation of the electrodes and the [...] Read more.

It is known that one factor that affects the operation of optoelectronic devices is the effective protection of the semiconductor materials against environmental conditions. The permeation of atmospheric oxygen and water molecules into the device structure induces degradation of the electrodes and the semiconductor. As a result, in this communication we report the fabrication of semiconductor membranes consisting of Magnesium Phthalocyanine-allene (MgPc-allene) particles dispersed in Nylon 11 films. These membranes combine polymer properties with organic semiconductors properties and also provide a barrier effect for the atmospheric gas molecules. They were prepared by high vacuum evaporation and followed by thermal relaxation technique. For the characterization of the obtained membranes, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to determine the chemical and microstructural properties. UV-ViS, null ellipsometry, and visible photoluminescence (PL) at room temperature were used to characterize the optoelectronic properties. These results were compared with those obtained for the organic semiconductors: MgPc-allene thin films. Additionally, semiconductor membranes devices have been prepared, and a study of the device electronic transport properties was conducted by measuring electrical current density-voltage (J-V) characteristics by four point probes with different wavelengths. The resistance properties against different environmental molecules are enhanced, maintaining their semiconductor functionality that makes them candidates for optoelectronic applications. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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17 pages, 1874 KiB

Open AccessArticle

Improving Kinetics of “Click-Crosslinking” for Self-Healing Nanocomposites by Graphene-Supported Cu-Nanoparticles

by Neda Kargarfard^1,2

, Norman Diedrich¹, Harald Rupp¹

, Diana Döhler^1,*

and Wolfgang H. Binder^1,*

¹ Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany

² Leibniz-Institut für Polymerforschung Dresden e. V., Abteilung Reaktive Verarbeitung, Hohe Str. 6, D-01069 Dresden, Germany

Polymers 2018, 10(1), 17; https://doi.org/10.3390/polym10010017 - 24 Dec 2017

Cited by 13 | Viewed by 6997

Abstract

Investigation of the curing kinetics of crosslinking reactions and the development of optimized catalyst systems is of importance for the preparation of self-healing nanocomposites, able to significantly extend their service lifetimes. Here we study different modified low molecular weight multivalent azides for a [...] Read more.

Investigation of the curing kinetics of crosslinking reactions and the development of optimized catalyst systems is of importance for the preparation of self-healing nanocomposites, able to significantly extend their service lifetimes. Here we study different modified low molecular weight multivalent azides for a capsule-based self-healing approach, where self-healing is mediated by graphene-supported copper-nanoparticles, able to trigger “click”-based crosslinking of trivalent azides and alkynes. When monitoring the reaction kinetics of the curing reaction via reactive dynamic scanning calorimetry (DSC), it was found that the “click-crosslinking” reactivity decreased with increasing chain length of the according azide. Additionally, we could show a remarkable “click” reactivity already at 0 °C, highlighting the potential of click-based self-healing approaches. Furthermore, we varied the reaction temperature during the preparation of our tailor-made graphene-based copper(I) catalyst to further optimize its catalytic activity. With the most active catalyst prepared at 700 °C and the optimized set-up of reactants on hand, we prepared capsule-based self-healing epoxy nanocomposites. Full article

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

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15 pages, 6582 KiB

Open AccessArticle

Reprocessing of PLA/Graphene Nanoplatelets Nanocomposites

by Luigi Botta

, Roberto Scaffaro

, Fiorenza Sutera and Maria Chiara Mistretta^*

Department of Civil, Environmental, Aerospace and Materials Engineering, University of Palermo, RU INSTM of Palermo, Viale delle Scienze, 90128 Palermo, Italy

Polymers 2018, 10(1), 18; https://doi.org/10.3390/polym10010018 - 24 Dec 2017

Cited by 80 | Viewed by 9339

Abstract

This work reports a study on the effect of multiple reprocessing on the properties of poly(lactic acid) (PLA) filled with graphene nanoplatelets (GnP) compared to the melt reprocessed neat polymeric matrix. In particular, morphological, X-Ray Diffraction and Micro-Raman analyses, intrinsic viscosity measurements, thermal, [...] Read more.

This work reports a study on the effect of multiple reprocessing on the properties of poly(lactic acid) (PLA) filled with graphene nanoplatelets (GnP) compared to the melt reprocessed neat polymeric matrix. In particular, morphological, X-Ray Diffraction and Micro-Raman analyses, intrinsic viscosity measurements, thermal, rheological and mechanical tests were carried out on materials reprocessed up five times by means of a single screw extruder. The results indicated that the presence of GnP decreased the degradation rate as a function of the reprocessing cycles in comparison with the neat PLA that, on the contrary, showed a more drastic reduction of the molecular weight. Moreover, the reprocessing improved the particle dispersion and reduced the presence of GnP aggregates. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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10 pages, 5446 KiB

Open AccessArticle

Preparation and Characterization of Novel Polyvinylidene Fluoride/2-Aminobenzothiazole Modified Ultrafiltration Membrane for the Removal of Cr(VI) in Wastewater

by Xiuju Wang^1,2,3,*,†, Kaili Zhou^1,2,†, Zhun Ma⁴, Xingjie Lu^1,2, Liguo Wang^1,2,3,*, Zhongpeng Wang^1,2,3,* and Xueli Gao⁵

¹ Key Laboratory of Water Resources and Environmental Engineering in Universities of Shandong, University of Jinan, Jinan 250022, China

² School of Resources and Environment, University of Jinan, Jinan 250022, China

³ Shandong Provincial Engineering Technology Research Center for Ecological Carbon Sink and Capture Utilization, Jinan 250022, China

⁴ College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China

⁵ Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China

^† These authors contributed equally to this work.

Polymers 2018, 10(1), 19; https://doi.org/10.3390/polym10010019 - 25 Dec 2017

Cited by 23 | Viewed by 5185

Abstract

Hexavalent chromium is one of the main heavy metal pollutants. As the environmental legislation becomes increasingly strict, seeking new technology to treat wastewater containing hexavalent chromium is becoming more and more important. In this research, a novel modified ultrafiltration membrane that could be [...] Read more.

Hexavalent chromium is one of the main heavy metal pollutants. As the environmental legislation becomes increasingly strict, seeking new technology to treat wastewater containing hexavalent chromium is becoming more and more important. In this research, a novel modified ultrafiltration membrane that could be applied to adsorb and purify water containing hexavalent chromium, was prepared by polyvinylidene fluoride (PVDF) blending with 2-aminobenzothiazole via phase inversion. The membrane performance was characterized by evaluation of the instrument of membrane performance, infrared spectroscopy (FTIR), scanning electron microscope (SEM), and water contact angle measurements. The results showed that the pure water flux of the PVDF/2-aminobenzothiazole modified ultrafiltration membrane was 231.27 L/m²·h, the contact angle was 76.1°, and the adsorption capacity of chromium ion was 157.75 µg/cm². The PVDF/2-aminobenzothiazole modified ultrafiltration membrane presented better adsorption abilities for chromium ion than that of the traditional PVDF membrane. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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25 pages, 3482 KiB

Open AccessArticle

Preparation of a Mini-Library of Thermo-Responsive Star (NVCL/NVP-VAc) Polymers with Tailored Properties Using a Hexafunctional Xanthate RAFT Agent

by Norma Aidé Cortez-Lemus^*

and Angel Licea-Claverie

Centro de Graduados e Investigación en Química, Instituto Tecnológico de Tijuana, A. P. 1166, Tijuana 22000, B. C., Mexico

Polymers 2018, 10(1), 20; https://doi.org/10.3390/polym10010020 - 24 Dec 2017

Cited by 17 | Viewed by 7273

Abstract

A mini-library of star-shaped thermoresponsive polymers having six arms was prepared using a hexafunctional xanthate by reversible addition–fragmentation chain transfer (RAFT) polymerization. Star polymers with homopolymeric arms of poly(N-vinylcaprolactam) (PNVCL), copolymeric arms of poly(N-vinylcaprolactam-co-N-vinylpyrrolidone) (PNVCL- [...] Read more.

A mini-library of star-shaped thermoresponsive polymers having six arms was prepared using a hexafunctional xanthate by reversible addition–fragmentation chain transfer (RAFT) polymerization. Star polymers with homopolymeric arms of poly(N-vinylcaprolactam) (PNVCL), copolymeric arms of poly(N-vinylcaprolactam-co-N-vinylpyrrolidone) (PNVCL-co-PNVP) and also arms of block copolymers of PNVCL-b-PVAc, (PNVCL-co-PNVP)-b-PVAc, and combinations of them changing the order of the block was achieved exploiting the R-RAFT synthetic methodology (or R-group approach), wherein the thiocarbonyl group is transferred to the polymeric chain end. Taking advantage of the RAFT benefits, the molecular weight of the star polymers was controlled (M_n = 11,880–153,400 g/mol) to yield star polymers of different sizes and lower critical solution temperature (LCST) values. Removing the xanthate group of the star polymers allowed for the introduction of specific functional groups at the ends of the star arms and resulted in an increase of the LCST values. Star PNVCL-b-PVAc diblock copolymers with PVAc contents of 5–26 mol % were prepared; the hydrophobic segment (PVAc) is located at the end of the star arms. Interestingly, when the PVAc content was 5–7 mol %, the hydrodynamic diameter (D_h) value of the aggregates formed in water was almost the same sa the D_h of the corresponding PNVCL star homopolymers. It is proposed that these star block copolymers self-assemble into single flowerlike micelles, showing great stability in aqueous solution. Star block copolymers with the PVAc hydrophobic block in the core of the star, such as PVAc-b-(PNVCL-co-PNVP), form micellar aggregates in aqueous solution with D_h values in the range from ~115 to 245 nm while maintaining a thermoresponsive behavior. Micellar aggregates of selected star polymers were used to encapsulate methotrexate (MTX) showing their potential in the temperature controlled release of this antineoplasic drug. The importance of the order in which each block constituent is introduced in the arms of the star polymers for their solution/aggregation behavior is demonstrated. Full article

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

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14 pages, 2763 KiB

Open AccessArticle

Antibacterial Films Made of Ionic Complexes of Poly(γ-glutamic acid) and Ethyl Lauroyl Arginate

by Ana Gamarra-Montes¹, Beatriz Missagia², Jordi Morató² and Sebastián Muñoz-Guerra^1,*

¹ Departament d’Enginyeria Química, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain

² Health and Environmental Microbiology Lab & UNESCO Chair on Sustainability, Universitat Politècnica de Catalunya, ESEIAAT, Ediﬁci Gaia, Pg. Ernest Lluch/Rambla Sant Nebridi, 08222 Terrassa, Spain

Polymers 2018, 10(1), 21; https://doi.org/10.3390/polym10010021 - 24 Dec 2017

Cited by 18 | Viewed by 6465

Abstract

The biocide agent LAE (ethyl ^αN-lauroyl l-arginate chloride) was coupled with poly(γ-glutamic acid) (PGGA) to form stable ionic complexes with LAE:PGGA ratios of 1 and 0.5. The nanostructure adopted by these complexes and its response to thermal changes were examined [...] Read more.

The biocide agent LAE (ethyl ^αN-lauroyl l-arginate chloride) was coupled with poly(γ-glutamic acid) (PGGA) to form stable ionic complexes with LAE:PGGA ratios of 1 and 0.5. The nanostructure adopted by these complexes and its response to thermal changes were examined in detail by Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) using synchrotron radiation in real time. A layered biphasic structure with LAE filling the space between the polypeptidic sheets was adopted in these complexes. The complexes were stable up to above 250 °C, non-water soluble, and were able to form consistent transparent films. The release of LAE from the complexes upon incubation in aqueous buffer was examined and found to depend on both pH and complex composition. The antibacterial activity of films made of these complexes against Gram-positive (L. monocytogenes and S. aureus) and Gram-negative (E. coli and S. enterica) bacteria was preliminary evaluated and was found to be very high against the formers and only moderate against the later. The bactericide activity displayed by the LAE·PGGA complexes was directly related with the amount of LAE that was released from the film to the environment. Full article

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

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18 pages, 12485 KiB

Open AccessArticle

Melamine–Glyoxal–Glutaraldehyde Wood Panel Adhesives without Formaldehyde

by Xuedong Xi

, Antonio Pizzi^*

and Siham Amirou

LERMAB, University of Lorraine, 27 rue Philippe Seguin, 88000 Epinal, France

Polymers 2018, 10(1), 22; https://doi.org/10.3390/polym10010022 - 24 Dec 2017

Cited by 42 | Viewed by 11444

Abstract

(MGG’) resin adhesives for bonding wood panels were prepared by a single step procedure, namely reacting melamine with glyoxal and simultaneously with a much smaller proportion of glutaraldehyde. No formaldehyde was used. The inherent slow hardening of this resin was overcome by the [...] Read more.

(MGG’) resin adhesives for bonding wood panels were prepared by a single step procedure, namely reacting melamine with glyoxal and simultaneously with a much smaller proportion of glutaraldehyde. No formaldehyde was used. The inherent slow hardening of this resin was overcome by the addition of N-methyl-2-pyrrolidone hydrogen sulphate ionic liquid as the adhesive hardener in the glue mix. The plywood strength results obtained were comparable with those obtained with melamine–formaldehyde resins pressed under the same conditions. Matrix assisted laser desorption ionisation time of flight (MALDI ToF) and Fourier transform Infrared (FTIR) analysis allowed the identification of the main oligomer species obtained and of the different types of linkages formed, as well as to indicate the multifaceted role of the ionic liquid. These resins are proposed as a suitable substitute for equivalent formaldehyde-based resins. Full article

(This article belongs to the Collection Polymeric Adhesives)

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16 pages, 18124 KiB

Open AccessArticle

Effects of Fluoro Substitution on the Electrochromic Performance of Alternating Benzotriazole and Benzothiadiazole-Based Donor–Acceptor Type Copolymers

by Yan Zhang^1,*, Lingqian Kong², Xiuping Ju² and Jinsheng Zhao^1,*

¹ Shandong Key Laboratory of Chemical Energy Storage and Novel Cell Technology, Liaocheng University, Liaocheng 252059, China

² Dongchang College, Liaocheng University, Liaocheng 252059, China

Polymers 2018, 10(1), 23; https://doi.org/10.3390/polym10010023 - 25 Dec 2017

Cited by 14 | Viewed by 5341

Abstract

Two new donor–acceptor type electrochromic copolymers containing non-fluorinated and di-fluorinated benzothiadiazole analogues, namely P(TBT-TBTh) and P(TBT-F-TBTh), were synthesized successfully through chemical polymerization. Both polymers were measured by cyclic voltammetry, UV-vis spectroscopy, colorimetry and thermogravimetric analysis to study the influence of fluoro substitution on [...] Read more.

Two new donor–acceptor type electrochromic copolymers containing non-fluorinated and di-fluorinated benzothiadiazole analogues, namely P(TBT-TBTh) and P(TBT-F-TBTh), were synthesized successfully through chemical polymerization. Both polymers were measured by cyclic voltammetry, UV-vis spectroscopy, colorimetry and thermogravimetric analysis to study the influence of fluoro substitution on the electrochromic performance. The results demonstrated that the two polymer films displayed well-defined redox peaks in pairs during the p-type doping, and showed distinct color change from dark gray blue to light green for P(TBT-TBTh) with the band gap of 1.51 eV, and from gray blue to celandine green for P(TBT-F-TBTh) with the band gap of 1.58 eV. P(TBT-F-TBTh) presented lower highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, and better stability than P(TBT-TBTh). It was found that the two fluorine atoms participated in not only inductive effects but also mesomeric effects in the P(TBT-F-TBTh) backbone. In addition, the polymers exhibited high optical contrasts, short response time, and favorable coloration efficiency, especially in the near infrared region. The characterization results indicated that the two reported polymers can be the potential choice as electrochromic materials. Full article

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

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26 pages, 5238 KiB

Open AccessArticle

Highly Productive Synthesis, Characterization, and Fluorescence and Heavy Metal Ion Adsorption Properties of Poly(2,5-dimercapto-1,3,4-thiadiazole) Nanosheets

by Chao Li^1,2, Shaojun Huang^1,*, 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(1), 24; https://doi.org/10.3390/polym10010024 - 25 Dec 2017

Cited by 23 | Viewed by 6100

Abstract

Poly(2,5-dimercapto-1,3,4-thiadiazole) (PBT) nanosheets were synthesized by chemical oxidative synthesis under mild conditions. The media, oxidant species, monomer concentrations, oxidant/monomer molar ratio, and temperature were optimized to achieve higher yields and better performance. The molecular structure, morphology, and properties of the nanosheets were analyzed [...] Read more.

Poly(2,5-dimercapto-1,3,4-thiadiazole) (PBT) nanosheets were synthesized by chemical oxidative synthesis under mild conditions. The media, oxidant species, monomer concentrations, oxidant/monomer molar ratio, and temperature were optimized to achieve higher yields and better performance. The molecular structure, morphology, and properties of the nanosheets were analyzed by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis), and fluorescence spectroscopies, wide-angle X-ray diffraction (WAXD), matrix-assisted laser desorption/ionization/time-of-flight (MALDI-TOF) mass spectrometry, X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). It was found that the polymerization of 2,5-dimercapto-1,3,4-thiadiazole occurs via dehydrogenation coupling between two mercapto groups to form the –S–S– bond. PBTs show the highest polymerization yield of up to 98.47% and form uniform nanosheets with a thickness of 89~367 nm. poly(2,5-dimercapto-1,3,4-thiadiazole) polymers (PBTs) exhibit good chemical resistance, high thermostability, interesting blue-light emitting fluorescence, and wonderful heavy metal ion adsorption properties. Particularly, the PBT nanosheets having a unique synergic combination of three kinds of active –S–, –SH, and =N– groups with a moderate specific area of 15.85 m² g⁻¹ exhibit an ultra-rapid initial adsorption rate of 10,653 mg g⁻¹ h⁻¹ and an ultrahigh adsorption capacity of up to 680.01 mg g⁻¹ for mercury ion, becoming ultrafast chelate nanosorbents with a high adsorption capacity. With these impressive properties, PBT nanosheets are very promising materials in the fields of water treatment, sensors, and electrodes. Full article

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19 pages, 3624 KiB

Open AccessArticle

Chitosan–Zinc(II) Complexes as a Bio-Sorbent for the Adsorptive Abatement of Phosphate: Mechanism of Complexation and Assessment of Adsorption Performance

by Maryam Roza Yazdani^1,*, Elina Virolainen¹, Kevin Conley² and Riku Vahala¹

¹ Water and Wastewater Engineering Research Group, School of Engineering, Aalto University, P.O. Box 15200, FI-00076 Aalto, Finland

² COMP Centre of Excellence, Department of Applied Physics, School of Science, Aalto University, FI-00076 Aalto, Finland

Polymers 2018, 10(1), 25; https://doi.org/10.3390/polym10010025 - 25 Dec 2017

Cited by 61 | Viewed by 9066

Abstract

This study examines zinc(II)–chitosan complexes as a bio-sorbent for phosphate removal from aqueous solutions. The bio-sorbent is prepared and is characterized via Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Point of Zero Charge (pH_PZC)–drift method. The adsorption capacity [...] Read more.

This study examines zinc(II)–chitosan complexes as a bio-sorbent for phosphate removal from aqueous solutions. The bio-sorbent is prepared and is characterized via Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Point of Zero Charge (pH_PZC)–drift method. The adsorption capacity of zinc(II)–chitosan bio-sorbent is compared with those of chitosan and ZnO–chitosan and nano-ZnO–chitosan composites. The effect of operational parameters including pH, temperature, and competing ions are explored via adsorption batch mode. A rapid phosphate uptake is observed within the first three hours of contact time. Phosphate removal by zinc(II)–chitosan is favored when the surface charge of bio-sorbent is positive/or neutral e.g., within the pH range inferior or around its pH_PZC, 7. Phosphate abatement is enhanced with decreasing temperature. The study of background ions indicates a minor effect of chloride, whereas nitrate and sulfate show competing effect with phosphate for the adsorptive sites. The adsorption kinetics is best described with the pseudo-second-order model. Sips (R² > 0.96) and Freundlich (R² ≥ 0.95) models suit the adsorption isotherm. The phosphate reaction with zinc(II)–chitosan is exothermic, favorable and spontaneous. The complexation of zinc(II) and chitosan along with the corresponding mechanisms of phosphate removal are presented. This study indicates the introduction of zinc(II) ions into chitosan improves its performance towards phosphate uptake from 1.45 to 6.55 mg/g and provides fundamental information for developing bio-based materials for water remediation. Full article

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

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10 pages, 2367 KiB

Open AccessArticle

A Facial Strategy for Catalyst and Reducing Agent Synchronous Separation for AGET ATRP Using Thiol-Grafted Cellulose Paper as Reducing Agent

by Xiaowu Jiang^*, Jie Han, Lunan Cao, Yan Bao, Jian Shi, Jing Zhang, Lingli Ni^* and Jing Chen

Jiangsu Provincial Key Laboratory of Palygorskite Science and Applied Technology, College of Chemical Engineering, Huaiyin Institute of Technology, Huai’an 223003, China

Polymers 2018, 10(1), 26; https://doi.org/10.3390/polym10010026 - 25 Dec 2017

Cited by 9 | Viewed by 5598

Abstract

Atom Transfer Radical Polymerization (ATRP) has been a powerful tool to synthesize well-defined functional polymers, which are widely used in biology, drug/gene delivery and antibacterial materials, etc. However, the potential toxic residues in polymer reduced its service life and limited its applications. In [...] Read more.

Atom Transfer Radical Polymerization (ATRP) has been a powerful tool to synthesize well-defined functional polymers, which are widely used in biology, drug/gene delivery and antibacterial materials, etc. However, the potential toxic residues in polymer reduced its service life and limited its applications. In order to overcome the problem, in this work, a novel polymerization system of activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) for synchronous separation of the metal catalyst and byproduct of reducing agent was developed, using thiol-grafted cellulose paper (Cell-SH) as a solid reducing agent. The polymerization kinetics were investigated in detail, and the “living” features of the novel polymerization system were confirmed by chain-end analysis and chain extension experiment for the resultant polymethyl methacrylate (PMMA). It is noted that the copper residual in obtained PMMA was less than 20 ppm, just by filtering the sheet-like byproduct of the reducing agent. Full article

(This article belongs to the Collection Polysaccharides)

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15 pages, 5194 KiB

Open AccessArticle

High-T_g, Low-Dielectric Epoxy Thermosets Derived from Methacrylate-Containing Polyimides

by Chien-Han Chen¹, Kuan-Wei Lee¹, Ching-Hsuan Lin^1,*, Ming-Jaan Ho², Mao-Feng Hsu³, Shou-Jui Hsiang², Nan-Kun Huang² and Tzong-Yuan Juang³

¹ Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan

² Zhen Ding Technology Holding Limited, Taoyuan 33754, Taiwan

³ Department of Cosmeceutics, China Medical University, Taichung 404, Taiwan

Polymers 2018, 10(1), 27; https://doi.org/10.3390/polym10010027 - 25 Dec 2017

Cited by 20 | Viewed by 8961

Abstract

Three methacrylate-containing polyimides (Px–MMA; x = 1–3) were prepared from the esterification of hydroxyl-containing polyimides (Px–OH; x = 1–3) with methacrylic anhydride. Px–MMA exhibits active ester linkages (Ph–O–C(=O)–) that can react with epoxy in the presence of 4-dimethylaminopyridine (DMAP), so Px–MMA acted as [...] Read more.

Three methacrylate-containing polyimides (Px–MMA; x = 1–3) were prepared from the esterification of hydroxyl-containing polyimides (Px–OH; x = 1–3) with methacrylic anhydride. Px–MMA exhibits active ester linkages (Ph–O–C(=O)–) that can react with epoxy in the presence of 4-dimethylaminopyridine (DMAP), so Px–MMA acted as a curing agent for a dicyclopentadiene-phenol epoxy (HP7200) to prepare epoxy thermosets (Px–MMA/HP7200; x = 1–3) thermosets. For property comparisons, P1–OH/HP7200 thermosets were also prepared. The reaction between active ester and epoxy results in an ester linkage, which is less polar than secondary alcohol resulting from the reaction between phenolic OH and epoxy, so P1–MMA/HP7200 are more hydrophobic and exhibit better dielectric properties than P1–OH/HP7200. The double bond of methacrylate can cure at higher temperatures, leading to epoxy thermosets with a high-T_g and moderate-to-low dielectric properties. Full article

(This article belongs to the Special Issue High Performance Polymers)

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10 pages, 2553 KiB

Open AccessArticle

Long-Term Stability and Integrity of Plasmid-Based DNA Data Storage

by Hoang Hiep Nguyen^1,2,†

, Jeho Park^1,2,†, Seon Joo Park¹, Chang-Soo Lee^1,2, Seungwoo Hwang³, Yong-Beom Shin^1,2, Tai Hwan Ha^1,2,* and Moonil Kim^1,2,4,*

¹ Hazards Monitoring Bionano Research Center, Daejeon, 34141, Korea

² Department of Nanobiotechnology, Korea University of Science and Technology (UST), 217 Gajeongno, Yuseong-Gu, Daejeon 34113, Korea

³ Korean Bioinformation Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahangno, Yuseong-Gu, Daejeon 34141, Korea

⁴ Department of Pathobiology, College of Veterinary Medicine Nursing & Allied Health (CVMNAH), Tuskegee University, Tuskegee, AL 36088, USA

^† These authors contributed equally to this work.

Polymers 2018, 10(1), 28; https://doi.org/10.3390/polym10010028 - 1 Jan 2018

Cited by 42 | Viewed by 12282

Abstract

Validation of long-term DNA stability and integrity are essential for the use of DNA in data storage applications. Because of this, we evaluated the plasmid-based DNA data storage in a manner that preserves DNA stability and integrity. A document consisting of 2046 words [...] Read more.

Validation of long-term DNA stability and integrity are essential for the use of DNA in data storage applications. Because of this, we evaluated the plasmid-based DNA data storage in a manner that preserves DNA stability and integrity. A document consisting of 2046 words was encoded with DNA sequences using Perl script, and the encoded DNA sequences were synthesized for information storage. The DNA comprised a total of 22 chemically synthesized DNA fragments with 400 nucleotides each, which were incorporated into a plasmid vector. A long-term DNA stability study demonstrated that 3-year stored plasmid containing text information showed DNA stability at controlled conditions of −20 °C. The plasmid DNA under accelerated aging conditions (AAC) up to 65 °C for 20 days, which corresponds to approximately 20 years of storage at −20 °C, also exhibited no significant differences in DNA stability compared to newly produced plasmid. Also, the 3-year old plasmid stored at −20 °C and the AAC-tested plasmid stored up to 65 °C for 20 days had functional integrity and nucleotide integrity comparable to control sample, thereby allowing for retrieval of the original error-free text data. Finally, the nucleotides were sequenced, and then decoded to retrieve the original data, thereby allowing us to read the text with 100% accuracy, and amplify the DNA with a simple and quick bacterial transformation. To the best of our knowledge, this is the first report on examining the long-term stability and integrity of plasmid-based DNA data storage. Taken together, our results indicate that plasmid DNA data storage can be useful for long-term archival storage to recover the source text in a reproducible and accountable manner. Full article

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11 pages, 6669 KiB

Open AccessArticle

Thermomechanical Behavior of Polymer Composites Based on Edge-Selectively Functionalized Graphene Nanosheets

by Ki-Ho Nam^1,†, Jaehyun Cho^1,† and Hyeonuk Yeo^2,*

¹ Institute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), Jeonbuk 565-902, Korea

² Department of Chemistry Education, Chemistry Building, Kyungpook National University, 80, Daehak-ro, Buk-gu, Daegu 41566, Korea

^† K.-H.N. and J.C. contributed equally to this work.

Polymers 2018, 10(1), 29; https://doi.org/10.3390/polym10010029 - 26 Dec 2017

Cited by 17 | Viewed by 6117

Abstract

In this study, we demonstrate an effective approach based on a simple processing method to improve the thermomechanical properties of graphene polymer composites (GPCs). Edge-selectively functionalized graphene (EFG) was successfully obtained through simple ball milling of natural graphite in the presence of dry [...] Read more.

In this study, we demonstrate an effective approach based on a simple processing method to improve the thermomechanical properties of graphene polymer composites (GPCs). Edge-selectively functionalized graphene (EFG) was successfully obtained through simple ball milling of natural graphite in the presence of dry ice, which acted as the source of carboxyl functional groups that were attached to the peripheral basal plane of graphene. The resultant EFG is highly dispersible in various organic solvents and contributes to improving their physical properties because of its unique characteristics. Pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) were used as monomers for constructing the polyimide (PI) backbone, after which PI/EFG composites were prepared by in situ polymerization. A stepwise thermal imidization method was used to prepare the PI films for comparison purposes. The PI/EFG composite films were found to exhibit reinforced thermal and thermo-mechanical properties compared to neat PI owing to the interaction between the EFG and PI matrix. Full article

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

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11 pages, 2193 KiB

Open AccessArticle

Theoretical Evaluation of the Influence of Molecular Packing Mode on the Intramolecular Reorganization Energy of Oligothiophene Molecules

by Bing Zhang^1,2,*, Yingxue Xu³, Lilin Zhu³, Shijie Zhou³, Yinjie Liao³, Kaixuan Zhou³, Jianxi Yao^1,2 and Songyuan Dai^2,3,*

¹ Beijing Key Laboratory of Energy Security and Clean Utilization, North China Electric Power University, Beijing 102206, China

² Beijing Key Laboratory of Novel Thin Film Solar Cells, North China Electric Power University, Beijing 102206, China

³ School of Renewable Energy, North China Electric Power University, Beijing 102206, China

Polymers 2018, 10(1), 30; https://doi.org/10.3390/polym10010030 - 27 Dec 2017

Cited by 5 | Viewed by 6685

Abstract

Accurate determination of the relationships among packing mode, molecular structure and charge transfer mobility for oligothiophene analogues has been significantly impeded, due to the lack of crystal structure information. In the current study, molecular dynamics (MD) were used to investigate the packing mode [...] Read more.

Accurate determination of the relationships among packing mode, molecular structure and charge transfer mobility for oligothiophene analogues has been significantly impeded, due to the lack of crystal structure information. In the current study, molecular dynamics (MD) were used to investigate the packing mode of non-, methyl- and ethyl-substituted poly(3-alkylthiophenes) (P3ATs). Obvious conformational changes were observed when comparing the packed and isolated oligothiophene molecules, indicating the important influence of packing mode on the geometric structures of these materials. Considering the crucial role played by reorganization energy (RE) in the charge transfer process, both quantum mechanics (QM) and quantum mechanics/molecular mechanics (QM/MM) were performed to examine the impact of different conformations on energy. Our simulations revealed that the geometric structures have distinct effects on the RE. Our data suggest that MD could give a reliable packing mode of oligothiophene analogues, and that QM/MM is indispensable for precisely estimating RE. Full article

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

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18 pages, 3383 KiB

Open AccessFeature PaperArticle

Micellization Thermodynamics of Pluronic P123 (EO₂₀PO₇₀EO₂₀) Amphiphilic Block Copolymer in Aqueous Ethylammonium Nitrate (EAN) Solutions

by Zhiqi He and Paschalis Alexandridis^*

Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260-4200, USA

Polymers 2018, 10(1), 32; https://doi.org/10.3390/polym10010032 - 28 Dec 2017

Cited by 69 | Viewed by 14213

Abstract

Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (commercially available as Pluronics or Poloxamers) can self-assemble into various nanostructures in water and its mixtures with polar organic solvents. Ethylammonium nitrate (EAN) is a well-known protic ionic liquid that is expected to affect amphiphile self-assembly [...] Read more.

Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (commercially available as Pluronics or Poloxamers) can self-assemble into various nanostructures in water and its mixtures with polar organic solvents. Ethylammonium nitrate (EAN) is a well-known protic ionic liquid that is expected to affect amphiphile self-assembly due to its ionic nature and hydrogen bonding ability. By proper design of isothermal titration calorimetry (ITC) experiments, we determined the enthalpy and other thermodynamic parameters of Pluronic P123 (EO₂₀PO₇₀EO₂₀) micellization in aqueous solution at varied EAN concentration. Addition of EAN promoted micellization in a manner similar to increasing temperature, e.g., the addition of 1.75 M EAN lowered the critical micelle concentration (CMC) to the same extent as a temperature increase from 20 to 24 °C. The presence of EAN disrupts the water solvation around the PEO-PPO-PEO molecules through electrostatic interactions and hydrogen bonding, which dehydrate PEO and promote micellization. At EAN concentrations lower than 1 M, the PEO-PPO-PEO micellization enthalpy and entropy increase with EAN concentration, while both decrease above 1 M EAN. Such a change can be attributed to the formation by EAN of semi-ordered nano-domains with water at higher EAN concentrations. Pyrene fluorescence suggests that the polarity of the mixed solvent decreased linearly with EAN addition, whereas the polarity of the micelle core remained unaltered. This work contributes to assessing intermolecular interactions in ionic liquid + polymer solutions, which are relevant to a number of applications, e.g., drug delivery, membrane separations, polymer electrolytes, biomass processing and nanomaterial synthesis. Full article

(This article belongs to the Special Issue Polymer Micelles)

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21 pages, 10953 KiB

Open AccessArticle

Polypropylene-Based Porous Membranes: Influence of Polymer Composition, Extrusion Draw Ratio and Uniaxial Strain

by Pilar Castejón¹, Kian Habibi¹, Amir Saffar², Abdellah Ajji², Antonio B. Martínez¹ and David Arencón^1,*

¹ Centre Català del Plàstic, Universitat Politècnica de Catalunya, C/Colom 114, Terrassa 08222, Spain

² Research Center for High Performance Polymers and Composite Systems, Chemical Engineering Department, Polytecnique Montréal, P.O. Box 6079, Montréal, QC H3C 3A7, Canada

Polymers 2018, 10(1), 33; https://doi.org/10.3390/polym10010033 - 29 Dec 2017

Cited by 29 | Viewed by 9063

Abstract

Several commercial grades of homo-polymer and its blends were selected to prepare microporous membranes through melt extrusion-annealing-uniaxial stretching technique (MEAUS). Branched or very fluid polypropylene was employed to modify the polymeric composition. In some blends, micro-sized calcium carbonate was added. We analysed the [...] Read more.

Several commercial grades of homo-polymer and its blends were selected to prepare microporous membranes through melt extrusion-annealing-uniaxial stretching technique (MEAUS). Branched or very fluid polypropylene was employed to modify the polymeric composition. In some blends, micro-sized calcium carbonate was added. We analysed the influence of sample composition, extrusion draw ratio, and we performed a deep study concerning the uniaxial strain rate, using in some cases extreme strain rates and strain extents. The crystalline features were studied by Differential Scanning Calorimetry (DSC), and the morphology of porous structure was analyzed through Scanning Electron Microscopy (SEM). Thermal stability and thermomechanical performance was measured by thermogravimetric analysis (TGA) and dynamic-mechanical-thermal (DTMA) study. A close relationship was found between crystalline characteristics, porous morphology and the trends registered for permeability. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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15 pages, 1899 KiB

Open AccessArticle

Improved Processability and the Processing-Structure-Properties Relationship of Ultra-High Molecular Weight Polyethylene via Supercritical Nitrogen and Carbon Dioxide in Injection Molding

by Galip Yilmaz^1,2, Thomas Ellingham^1,2

and Lih-Sheng Turng^1,2,*

¹ Polymer Engineering Center, Department of Mechanical Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA

² Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA

Polymers 2018, 10(1), 36; https://doi.org/10.3390/polym10010036 - 30 Dec 2017

Cited by 34 | Viewed by 8477

Abstract

The processability of injection molding ultra-high molecular weight polyethylene (UHMWPE) was improved by introducing supercritical nitrogen (scN₂) or supercritical carbon dioxide (scCO₂) into the polymer melt, which decreased its viscosity and injection pressure while reducing the risk of degradation. [...] Read more.

The processability of injection molding ultra-high molecular weight polyethylene (UHMWPE) was improved by introducing supercritical nitrogen (scN₂) or supercritical carbon dioxide (scCO₂) into the polymer melt, which decreased its viscosity and injection pressure while reducing the risk of degradation. When using the special full-shot option of microcellular injection molding (MIM), it was found that the required injection pressure decreased by up to 30% and 35% when scCO₂ and scN₂ were used, respectively. The mechanical properties in terms of tensile strength, Young’s modulus, and elongation-at-break of the supercritical fluid (SCF)-loaded samples were examined. The thermal and rheological properties of regular and SCF-loaded samples were analyzed using differential scanning calorimetry (DSC) and parallel-plate rheometry, respectively. The results showed that the temperature dependence of UHMWPE was very low, suggesting that increasing the processing temperature is not a viable method for reducing injection pressure or improving processability. Moreover, the use of scN₂ and scCO₂ with UHMWPE and MIM retained the high molecular weight, and thus the mechanical properties, of the polymer, while regular injection molding led to signs of degradation. Full article

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

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13 pages, 1335 KiB

Open AccessArticle

Solubility, Emulsification and Surface Properties of Maleic Anhydride, Perfluorooctyl and Alkyl Meth-Acrylate Terpolymers

by Marian Szkudlarek¹, Uwe Beginn^2,*, Helmut Keul¹ and Martin Möller^1,*

¹ DWI Leibniz Institute for Interactive Materials and Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Forckenbeckstraße 50, D-52056 Aachen, Germany

² Universität Osnabrück, Institut für Chemie, OMC, Barbarastraße 7, D-49076 Osnabrück, Germany

Polymers 2018, 10(1), 37; https://doi.org/10.3390/polym10010037 - 30 Dec 2017

Cited by 4 | Viewed by 5990

Abstract

The solubility of terpolymers containing alkyl, and perfluoroalkyl side chains as well as succinic acid moieties in the main chain, P[R_FMA_0.2-co-R_HMA_0.65-co-MAH_0.15] (R_H = C₄H₉- [...] Read more.

The solubility of terpolymers containing alkyl, and perfluoroalkyl side chains as well as succinic acid moieties in the main chain, P[R_FMA_0.2-co-R_HMA_0.65-co-MAH_0.15] (R_H = C₄H₉- or C₁₂H₂₅-, R_F- = C₁₀H₄F₁₉-) with ca. 20 mol % fluorinated side chains and 10–22 mol % of succinic anhydride rings was tested in a number of solvents varying from water to non polar mineral oils. The polymers are well soluble in fluorinated solvents like Freon-113^® and 1,3-bis(trifluoromethyl) benzene, in semi-polar solvents like chloroform, THF or lower esters and also in hydrocarbons with polymers containing dodecyl methacrylate. In self-emulsification experiments, a stable water emulsion of P[F8H2MA_0.2-co-BMA_0.65-co-MAH_0.15] was obtained. The dispersability and emulsification of these polymers in mixtures of organic solvents and water yielded stable emulsions in the presence of additional surfactant. Thin films coated from organic solutions as well as from emulsions on glass resulted in water and oil-repelling surfaces with contact angles up to 140° against water and 71° against hexadecane. An enhancing effect of annealing was not observed. Full article

(This article belongs to the Special Issue Fluorinated Polymers)

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12 pages, 1999 KiB

Open AccessArticle

Calculation of the Contact Angle of Polymer Melts on Tool Surfaces from Viscosity Parameters

by Gernot Zitzenbacher^1,*

, Hannes Dirnberger¹, Manuel Längauer¹ and Clemens Holzer²

¹ Department of Materials Technology, School of Engineering, University of Applied Sciences Upper Austria, 4600 Wels, Austria

² Department Polymer Engineering and Science, Chair of Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria

Polymers 2018, 10(1), 38; https://doi.org/10.3390/polym10010038 - 30 Dec 2017

Cited by 30 | Viewed by 8461

Abstract

It is of great importance for polymer processing whether and how viscosity influences the wettability of tool surfaces. We demonstrate the existence of a distinct relationship between the contact angle of molten polymers and zero shear viscosity in this paper. The contact angle [...] Read more.

It is of great importance for polymer processing whether and how viscosity influences the wettability of tool surfaces. We demonstrate the existence of a distinct relationship between the contact angle of molten polymers and zero shear viscosity in this paper. The contact angle of molten polypropylene and polymethylmethacrylate on polished steel was studied in a high temperature chamber using the sessile drop method. A high pressure capillary rheometer with a slit die was employed to determine the shear viscosity curves in a low shear rate range. A linear relation between the contact angle and zero shear viscosity was obtained. Furthermore, the contact angle and the zero shear viscosity values of the different polymers were combined to one function. It is revealed that, for the wetting of tool surfaces by molten polymers, a lower viscosity is advantageous. Furthermore, a model based on the temperature shift concept is proposed which allows the calculation of the contact angle of molten polymers on steel for different temperatures directly from shear viscosity data. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

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15 pages, 43967 KiB

Open AccessArticle

Vascular Cell Co-Culture on Silk Fibroin Matrix

by Fangfang Tu¹, Yunfei Liu¹, Helei Li¹, Pange Shi¹, Yunxia Hao¹, Yue Wu¹, Honggen Yi², Yin Yin³ and Jiannan Wang^1,2,*

¹ College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, Jiangsu, China

² National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123, Jiangsu, China

³ Laboratory Animal Research Center, Soochow University, Suzhou 215123, Jiangsu, China

Polymers 2018, 10(1), 39; https://doi.org/10.3390/polym10010039 - 1 Jan 2018

Cited by 16 | Viewed by 5762

Abstract

Silk fibroin (SF), a natural polymer material possessing excellent biocompatibility and biodegradability, and has been widely used in biomedical applications. In order to explore the behavior of vascular cells by co-culturing on regenerated SF matrix for use as artificial blood vessels, human aorta [...] Read more.

Silk fibroin (SF), a natural polymer material possessing excellent biocompatibility and biodegradability, and has been widely used in biomedical applications. In order to explore the behavior of vascular cells by co-culturing on regenerated SF matrix for use as artificial blood vessels, human aorta vascular smooth muscle cells (HAVSMCs) were co-cultured with human arterial fibroblasts (HAFs) or human umbilical vein endothelial cells (HUVECs) on SF films and SF tubular scaffolds (SFTSs). Analysis of cell morphology and deoxyribonucleic acid (DNA) content showed that HUVECs, HAVSMCs and HAFs adhered and spread well, and exhibited high proliferative activity whether cultured alone or in co-culture. Immunofluorescence and scanning electron microscopy (SEM) analysis showed that HUVECs and HAFs co-existed well with HAVSMCs on SF films or SFTSs. Cytokine expression determined by reverse transcription-polymerase chain reaction (RT-PCR) indicated that the expression levels of α-smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SM-MHC) in HAVSMCs were inhibited on SF films or SFTSs, but expression could be obviously promoted by co-culture with HUVECs or HAFs, especially that of SM-MHC. On SF films, the expression of vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule-1 (CD31) in HUVECs was promoted, and the expression levels of both increased obviously when co-cultured with HAVSMCs, with the expression levels of VEGF increasing with increasing incubation time. The expression levels of VEGF and CD31 in cells co-cultured on SFTSs improved significantly from day 3 compared with the mono-culture group. These results were beneficial to the mechanism analysis on vascular cell colonization and vascular tissue repair after in vivo transplantation of SFTSs. Full article

(This article belongs to the Special Issue Protein Biopolymer)

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17 pages, 5430 KiB

Open AccessArticle

Independent Evaluation of Medical-Grade Bioresorbable Filaments for Fused Deposition Modelling/Fused Filament Fabrication of Tissue Engineered Constructs

by Mina Mohseni, Dietmar W. Hutmacher

and Nathan J. Castro^*

Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane City 4059, QLD, Australia

Polymers 2018, 10(1), 40; https://doi.org/10.3390/polym10010040 - 2 Jan 2018

Cited by 47 | Viewed by 8784

Abstract

Three-dimensional printing/additive manufacturing (3DP/AM) for tissue engineering and regenerative medicine (TE/RM) applications is a multifaceted research area encompassing biology, material science, engineering, and the clinical sciences. Although being quite mature as a research area, only a handful of clinical cases have been reported [...] Read more.

Three-dimensional printing/additive manufacturing (3DP/AM) for tissue engineering and regenerative medicine (TE/RM) applications is a multifaceted research area encompassing biology, material science, engineering, and the clinical sciences. Although being quite mature as a research area, only a handful of clinical cases have been reported and even fewer commercial products have made it to the market. The regulatory pathway and costs associated with the introduction of bioresorbable materials for TE/RM have proven difficult to overcome, but greater access to 3DP/AM has spurred interest in the processing and availability of existing and new bioresorbable materials. For this purpose, herein, we introduce a series of medical-grade filaments for fused deposition modelling/fused filament fabrication (FDM/FFF) based on established and Federal Drug Administration (FDA)-approved polymers. Manufacturability, mechanical characterization, and accelerated degradation studies have been conducted to evaluate the suitability of each material for TE/RM applications. The comparative data serves to introduce these materials, as well as a benchmark to evaluate their potential in hard and soft tissue engineering from a physicochemical perspective. Full article

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

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9 pages, 1171 KiB

Open AccessArticle

High Temperature, Living Polymerization of Ethylene by a Sterically-Demanding Nickel(II) α-Diimine Catalyst

by Lauren A. Brown, W. Curtis Anderson, Nolan E. Mitchell, Kevin R. Gmernicki and Brian K. Long^*

Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA

Polymers 2018, 10(1), 41; https://doi.org/10.3390/polym10010041 - 2 Jan 2018

Cited by 34 | Viewed by 6285

Abstract

Catalysts that employ late transition-metals, namely Ni and Pd, have been extensively studied for olefin polymerizations, co-polymerizations, and for the synthesis of advanced polymeric structures, such as block co-polymers. Unfortunately, many of these catalysts often exhibit poor thermal stability and/or non-living polymerization behavior [...] Read more.

Catalysts that employ late transition-metals, namely Ni and Pd, have been extensively studied for olefin polymerizations, co-polymerizations, and for the synthesis of advanced polymeric structures, such as block co-polymers. Unfortunately, many of these catalysts often exhibit poor thermal stability and/or non-living polymerization behavior that limits their ability to access tailored polymer structures. Due to this, the development of catalysts that display controlled/living behavior at elevated temperatures is vital. In this manuscript, we describe a Ni α-diimine complex that is capable of polymerizing ethylene in a living manner at temperatures as high as 75 °C, which is one of the highest temperatures reported for the living polymerization of ethylene by a late transition metal-based catalyst. Furthermore, we will demonstrate that this catalyst’s living behavior is not dependent on the presence of monomer, and that it can be exploited to access polyethylene-based block co-polymers. Full article

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

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18 pages, 8270 KiB

Open AccessArticle

Green and Facile Synthesis of Highly Stable Gold Nanoparticles via Hyperbranched Polymer In-Situ Reduction and Their Application in Ag⁺ Detection and Separation

by Xunyong Liu^1,*, Chenxue Zhu¹, Li Xu¹, Yuqing Dai¹, Yanli Liu² and Yi Liu^1,*

¹ School of Chemistry and Materials Science, Ludong University, Yantai 264025, Shandong Province, China

² School of Information and Electronic Engineering, Shandong Technology and Business University, Yantai 264005, Shandong Province, China

Polymers 2018, 10(1), 42; https://doi.org/10.3390/polym10010042 - 3 Jan 2018

Cited by 23 | Viewed by 5819

Abstract

The development of a green and facile strategy for synthesizing high stable gold nanoparticles (AuNPs) is still highly challenging. Additionally, the main problems regarding AuNPs based colorimetric sensors are their poor selectivity and low sensitivity, as well their tendency to aggregate during their [...] Read more.

The development of a green and facile strategy for synthesizing high stable gold nanoparticles (AuNPs) is still highly challenging. Additionally, the main problems regarding AuNPs based colorimetric sensors are their poor selectivity and low sensitivity, as well their tendency to aggregate during their synthesis and sensing process. Herein, we present an in-situ reduction strategy to synthesize thermoresponsive hyperbranched polymer (i.e., Hyperbranched polyethylenimine-terminal isobutyramide (HPEI-IBAm)) functionalized AuNPs. The HPEI-IBAm-AuNPs show excellent thermal stability up to 200 °C, high tolerance of a wide range of pH value (3–13), and high salt resistance. HPEI-IBAm acted as the template, the reducing agent, and the stabilizing agent for the preparation of AuNPs. The HPEI-IBAm-AuNPs can be used as colorimetric sensors for the detection of Ag⁺. In the detecting process, HPEI-IBAm serves as a trigger agent to cause an unusual color change from red to brown. This new non-aggregation-based colorimetric sensor showed high stability (maintaining the color lasting without fading), high selectivity, and high sensitivity with an extremely low detection limit of 7.22 nM and a good linear relationship in a wide concentration range of 0–2.0 mM (R² = 0.9921). Significantly, based on the thermoresponsive property of the HPEI-IBAm, the AuNPs/Ag composites can be separated after sensing detection, which can avoid secondary pollutions. Therefore, the green preparation and the applications of the unusual colorimetric sensor truly embody the concepts of energy saving, environmental protection, and sustainable development. Full article

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

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16 pages, 5121 KiB

Open AccessArticle

Epoxy Vitrimers: The Effect of Transesterification Reactions on the Network Structure

by Facundo Ignacio Altuna

, Cristina Elena Hoppe and Roberto Juan José Williams^*

Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), Av. J. B. Justo 4302, 7600 Mar del Plata, Argentina

Polymers 2018, 10(1), 43; https://doi.org/10.3390/polym10010043 - 3 Jan 2018

Cited by 92 | Viewed by 11812

Abstract

Vitrimers are covalently crosslinked polymers that behave as conventional thermosets below the glass transition temperature (T_g) but can flow above a particular temperature, T_v > T_g, by bond exchange reactions. In epoxy vitrimers, transesterification reactions are responsible for [...] Read more.

Vitrimers are covalently crosslinked polymers that behave as conventional thermosets below the glass transition temperature (T_g) but can flow above a particular temperature, T_v > T_g, by bond exchange reactions. In epoxy vitrimers, transesterification reactions are responsible for their behavior at T > T_v that enables flow, thermoforming, recycling, self-healing and stress relaxation. A statistical analysis based on the fragment approach was performed to analyze the evolution of the network structure of epoxy vitrimers during transesterification reactions. An analytical solution was obtained for a formulation based on a diepoxide and a dicarboxylic acid. A numerical solution was derived for the reaction of a diepoxide with a tricarboxylic acid, as an example of the way to apply the model to polyfunctional monomers. As transesterification acts as a disproportionation reaction that converts two linear fragments (monoesters) into a terminal fragment (glycol) and a branching fragment (diester), its effect on network structure is to increase the concentration of crosslinks and pendant chains while leaving a sol fraction. Changes in the network structure of the epoxy vitrimer can take place after their synthesis, during their use at high temperatures, a fact that has to be considered in their technological applications. Full article

(This article belongs to the Special Issue Thermosets)

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12 pages, 2545 KiB

Open AccessArticle

Ionic Liquid as Surfactant Agent of Hydrotalcite: Influence on the Final Properties of Polycaprolactone Matrix

by Luanda Chaves Lins^1,2, Valeria Bugatti³

, Sébastien Livi^1,2 and Giuliana Gorrasi^3,*

¹ University of Lyon, F-69003 Lyon, France

² UMR 5223, Department of Engineering of Polymeric Materials, INSA Lyon, CNRS, F-69621 Villeurbanne, France

³ Department of Industrial Engineering, University of Salerno-via Giovanni Paolo II, 132, 84084 Fisciano (Salerno), Italy

Polymers 2018, 10(1), 44; https://doi.org/10.3390/polym10010044 - 5 Jan 2018

Cited by 34 | Viewed by 5197

Abstract

This paper reports the surface treatment of layered double hydroxide (LDH) by using ionic liquid (IL) composed of phosphonium cation combined with 2-ethylhexanoate (EHT) counter anion as surfactant agent. Then, different amounts (1, 3, 5 and 7 wt %) of thermally stable organically [...] Read more.

This paper reports the surface treatment of layered double hydroxide (LDH) by using ionic liquid (IL) composed of phosphonium cation combined with 2-ethylhexanoate (EHT) counter anion as surfactant agent. Then, different amounts (1, 3, 5 and 7 wt %) of thermally stable organically modified LDH (up to 350 °C) denoted LDH-EHT were incorporated into polycaprolactone (PCL) matrix by mechanical milling. The influence of LDH-EHT loading has been investigated on the physical properties, such as the thermal and barrier properties, as well as the morphologies of the resulting nanocomposites. Thus, intercalated or microcomposite morphologies were obtained depending on the LDH-EHT loading, leading to significant reduction of the diffusion coefficient respect to water vapor. The modulation of barrier properties, using low functionalized filler amount, is a very important aspect for materials in packaging applications. Full article

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

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16 pages, 2842 KiB

Open AccessArticle

Effect of Dendrigraft Generation on the Interaction between Anionic Polyelectrolytes and Dendrigraft Poly(l-Lysine)

by Feriel Meriem Lounis, Joseph Chamieh

, Laurent Leclercq

, Philippe Gonzalez, Jean-Christophe Rossi and Hervé Cottet^*

IBMM, Université de Montpellier, CNRS, ENSCM, 34095 Montpellier, France

Polymers 2018, 10(1), 45; https://doi.org/10.3390/polym10010045 - 4 Jan 2018

Cited by 13 | Viewed by 3787

Abstract

In this present work, three generations of dendrigraft poly(l-Lysine) (DGL) were studied regarding their ability to interact with linear poly (acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonate) (PAMAMPS) of different chemical charge densities (30% and 100%). Frontal analysis continuous capillary electrophoresis (FACCE) was successfully applied [...] Read more.

In this present work, three generations of dendrigraft poly(l-Lysine) (DGL) were studied regarding their ability to interact with linear poly (acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonate) (PAMAMPS) of different chemical charge densities (30% and 100%). Frontal analysis continuous capillary electrophoresis (FACCE) was successfully applied to determine binding constants and binding stoichiometries. The effect of DGL generation on the interaction was evaluated for the first three generations (G2, G3, and G4) at different ionic strengths, and the effect of ligand topology (linear PLL vs. dendrigraft DGL) on binding parameters was evaluated. An increase of the biding site constants accompanied with a decrease of the DGL-PAMAMPS (n:1) stoichiometry was observed for increasing DGL generation. The logarithm of the global binding constants decreased linearly with the logarithm of the ionic strength. This double logarithmic representation allowed determining the extent of counter-ions released from the association of DGL molecules onto one PAMAMPS chain that was compared to the total entropic reservoir constituted by the total number of condensed counter-ions before the association. Full article

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

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16 pages, 8684 KiB

Open AccessArticle

Block Copolymer Elastomer with Graphite Filler: Effect of Processing Conditions and Silane Coupling Agent on the Composite Properties

by Denis Mihaela Panaitescu^1,*

, Raluca Augusta Gabor¹, Cristian Andi Nicolae¹, Anca Constantina Parau², Catalin Vitelaru², Valentin Raditoiu¹

and Mircea Chipara³

¹ Polymer Department, National Institute for Research and Development in Chemistry and Petrochemistry, 202 Spl. Independentei, Bucharest 060021, Romania

² National Institute for Optoelectronics INOE 2000, 409 Atomistilor St., Magurele 077125, Romania

³ Department of Physics and Astronomy, The University of Texas Rio Grande Valley, 1201 W. University Drive, Edinburg, TX 78539, USA

Polymers 2018, 10(1), 46; https://doi.org/10.3390/polym10010046 - 4 Jan 2018

Cited by 19 | Viewed by 6756

Abstract

The control of morphology and interface in poly(styrene-ethylene/butylene-styrene) (SEBS) composites with graphitic fillers is extremely important for the design of piezoresistive sensors for body motion or flexible temperature sensors. The effects of a high amount of graphite (G) and silane coupling agent on [...] Read more.

The control of morphology and interface in poly(styrene-ethylene/butylene-styrene) (SEBS) composites with graphitic fillers is extremely important for the design of piezoresistive sensors for body motion or flexible temperature sensors. The effects of a high amount of graphite (G) and silane coupling agent on the morphology and properties of SEBS composites with anisotropic mechanical properties are reported. The physical and chemical bonding of silane to both G and SEBS surface was proved by EDX and TGA results; this improved interface influenced both the thermal and mechanical properties of the composite. The vinyltriethoxysilane (VS) promoted the formation of char residue and, being tightly bound to both SEBS and G, did not show separate decomposition peak in the TGA curve of composites. The mechanical properties were measured on two perpendicular directions and were improved by both the addition of VS and the increased amount of G; however, the increase of storage modulus due to orientation (from 5 to 15 times depending on the composition and direction of the test) was more important than that provided by the increase of G concentration, which was a maximum of four times that obtained for 15 wt % graphite. A mechanism to explain the influence of G content and treatment on the variation of storage modulus and tan δ depending on the direction of the test was also proposed. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

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14 pages, 4105 KiB

Open AccessArticle

Rheo-Kinetic Study of Sol-Gel Phase Transition of Chitosan Colloidal Systems

by Piotr Owczarz¹

, Patryk Ziółkowski^1,*, Zofia Modrzejewska², Sławomir Kuberski³ and Marek Dziubiński¹

¹ Department of Chemical Engineering, Lodz University of Technology, Lodz 90-924, Poland

² Department of Environmental Engineering, Lodz University of Technology, Lodz 90-924, Poland

³ Department of Molecular Engineering, Lodz University of Technology, Lodz 90-924, Poland

Polymers 2018, 10(1), 47; https://doi.org/10.3390/polym10010047 - 5 Jan 2018

Cited by 22 | Viewed by 6005

Abstract

Chitosan colloidal systems, created by dispersing in aqueous solutions of hydrochloric acid, with and without the addition of disodium β-glycerophosphate (β-NaGP), were prepared for the investigation of forming mechanisms of chitosan hydrogels. Three types of chitosan were used in varying molecular weights. The [...] Read more.

Chitosan colloidal systems, created by dispersing in aqueous solutions of hydrochloric acid, with and without the addition of disodium β-glycerophosphate (β-NaGP), were prepared for the investigation of forming mechanisms of chitosan hydrogels. Three types of chitosan were used in varying molecular weights. The impacts of the charge and shape of the macromolecules on the phase transition process were assessed. The chitosan system without the addition of β-NaGP was characterized by stiff and entangled molecules, in contrast to the chitosan system with the addition of β-NaGP, wherein the molecules adopt a more flexible and disentangled form. Differences in molecules shapes were confirmed using the Zeta potential and thixotropy experiments. The chitosan system without β-NaGP revealed a rapid nature of phase transition—consistent with diffusion-limited aggregation (DLA). The chitosan system with β-NaGP revealed a two-step nature of phase transition, wherein the first step was consistent with reaction-limited aggregation (RLA), while the second step complied with diffusion-limited aggregation (DLA). Full article

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

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14 pages, 2445 KiB

Open AccessArticle

A Comparative Study of Poly(Azure A) Film-Modified Disposable Electrodes for Electrocatalytic Oxidation of H₂O₂: Effect of Doping Anion

by Jerónimo Agrisuelas, María-Isabel González-Sánchez^†, Beatriz Gómez-Monedero and Edelmira Valero^*

¹ Department of Physical Chemistry, School of Industrial Engineers, University of Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain

^† Present address: Department of Physical Chemistry, Faculty of Chemistry, University of Valencia, C/Dr. Moliner 50, 46100 Burjassot, Spain.

Polymers 2018, 10(1), 48; https://doi.org/10.3390/polym10010048 - 6 Jan 2018

Cited by 14 | Viewed by 5767

Abstract

In the present paper, poly(azure A) (PAA) films were electrosynthetized in the presence of different doping anions on disposable screen-printed carbon electrodes (SPCEs). The anions used included inorganic monoatomic (chloride and fluoride), inorganic polyatomic (nitrate and sulfate) and organic polyatomic (dodecyl sulfate, DS) [...] Read more.

In the present paper, poly(azure A) (PAA) films were electrosynthetized in the presence of different doping anions on disposable screen-printed carbon electrodes (SPCEs). The anions used included inorganic monoatomic (chloride and fluoride), inorganic polyatomic (nitrate and sulfate) and organic polyatomic (dodecyl sulfate, DS) species. The coated electrodes thus obtained were characterized by electrochemical techniques and SEM. They showed improved electrocatalytic activities towards hydrogen peroxide oxidation compared to that of a bare SPCE. In particular, the insertion of DS anions inside PAA films provided a special sensitivity to the electrocatalysis of H₂O₂, which endowed these electrodes with promising analytical features for H₂O₂ quantification. We obtained a wide linear response for H₂O₂ within a range of 5 µM to 3 mM and a limit of detection of 1.43 ± 0.10 µM (signal-to-noise ratio of 3). Furthermore, sensitivity was 72.4 ± 0.49 nA·µM⁻¹∙cm⁻² at a relatively low electrocatalytic oxidation overpotential of 0.5 V vs. Ag. The applicability of this boosted system was tested by the analysis of H₂O₂ in commercial samples of a hair lightener and an antiseptic and was corroborated by spectrophotometric methods. Full article

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

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16 pages, 2300 KiB

Open AccessArticle

Theoretical Study on Synchronous Characterization of Surface and Interfacial Mechanical Properties of Thin-Film/Substrate Systems with Residual Stress Based on Pressure Blister Test Technique

by Zhi-xin Yang¹, Jun-yi Sun^1,2,*

, Ke Li¹, Yong-sheng Lian¹, Xiao-ting He^1,2

and Zhou-lian Zheng^1,2

¹ School of Civil Engineering, Chongqing University, Chongqing 400045, China

² Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing 400045, China

Polymers 2018, 10(1), 49; https://doi.org/10.3390/polym10010049 - 7 Jan 2018

Cited by 13 | Viewed by 6603

Abstract

In this study, based on the pressure blister test technique, a theoretical study on the synchronous characterization of surface and interfacial mechanical properties of thin-film/substrate systems with residual stress was presented, where the problem of axisymmetric deformation of a blistering film with initial [...] Read more.

In this study, based on the pressure blister test technique, a theoretical study on the synchronous characterization of surface and interfacial mechanical properties of thin-film/substrate systems with residual stress was presented, where the problem of axisymmetric deformation of a blistering film with initial stress was analytically solved and its closed-form solution was presented. The expressions to determine Poisson’s ratios, Young’s modulus, and residual stress of surface thin films were derived; the work done by the applied external load and the elastic energy stored in the blistering thin film were analyzed in detail and their expressions were derived; and the interfacial adhesion energy released per unit delamination area of thin-film/substrate (i.e., energy release rate) was finally presented. The synchronous characterization technique presented here has theoretically made a big step forward, due to the consideration for the residual stress in surface thin films. Full article

(This article belongs to the Collection Polymeric Adhesives)

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14 pages, 3825 KiB

Open AccessArticle

Gellan Gum/Pectin Beads Are Safe and Efficient for the Targeted Colonic Delivery of Resveratrol

by Fabíola Garavello Prezotti¹, Fernanda Isadora Boni¹, Natália Noronha Ferreira¹, Daniella De Souza e Silva², Sérgio Paulo Campana-Filho², Andreia Almeida^3,4,5, Teófilo Vasconcelos^3,4, Maria Palmira Daflon Gremião¹, Beatriz Stringhetti Ferreira Cury¹ and Bruno Sarmento^3,4,5,6,*

¹ Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista (UNESP), Araraquara, Rodovia Araraquara–Jaú, Km 1, Araraquara 14801-902, Brazil

² Instituto de Química de São Carlos, Universidade de São Paulo (USP), Avenida Trabalhador São-Carlense, 400, São Carlos 13560-970, Brazil

³ I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal

⁴ INEB-Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal

⁵ CESPU-Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Rua Central de Gandra 1317, 4585-116 Gandra, Portugal

⁶ School of Pharmacy, Queen’s University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK

Polymers 2018, 10(1), 50; https://doi.org/10.3390/polym10010050 - 8 Jan 2018

Cited by 59 | Viewed by 6044

Abstract

This work addresses the establishment and characterization of gellan gum:pectin (GG:P) biodegradable mucoadhesive beads intended for the colon-targeted delivery of resveratrol (RES). The impact of the polymer carrier system on the cytotoxicity and permeability of RES was evaluated. Beads of circular shape (circularity [...] Read more.

This work addresses the establishment and characterization of gellan gum:pectin (GG:P) biodegradable mucoadhesive beads intended for the colon-targeted delivery of resveratrol (RES). The impact of the polymer carrier system on the cytotoxicity and permeability of RES was evaluated. Beads of circular shape (circularity index of 0.81) with an average diameter of 914 μm, Span index of 0.29, and RES entrapment efficiency of 76% were developed. In vitro drug release demonstrated that beads were able to reduce release rates in gastric media and control release for up to 48 h at an intestinal pH of 6.8. Weibull’s model correlated better with release data and b parameter (0.79) indicated that the release process was driven by a combination of Fickian diffusion and Case II transport, indicating that both diffusion and swelling/polymer chains relaxation are processes that contribute equally to control drug release rates. Beads and isolated polymers were observed to be safe for Caco-2 and HT29-MTX intestinal cell lines. RES encapsulation into the beads allowed for an expressive reduction of drug permeation in an in vitro triple intestinal model. This feature, associated with low RES release rates in acidic media, can favor targeted drug delivery from the beads in the colon, a promising behavior to improve the local activity of RES. Full article

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

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21 pages, 4803 KiB

Open AccessArticle

Development and Characterization of Defect-Free Matrimid^® Mixed-Matrix Membranes Containing Activated Carbon Particles for Gas Separation

by Fynn Weigelt^1,†, Prokopios Georgopanos^1,*,†

, Sergey Shishatskiy¹

, Volkan Filiz¹, Torsten Brinkmann¹ and Volker Abetz^1,2,*

¹ Helmholtz-Zentrum Geesthacht, Institute of Polymer Research, Max-Planck-Straße 1, 21502 Geesthacht, Germany

² Institute of Physical Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany

^† These authors contributed equally to this work.

Polymers 2018, 10(1), 51; https://doi.org/10.3390/polym10010051 - 8 Jan 2018

Cited by 61 | Viewed by 9460

Abstract

In this work, mixed-matrix membranes (MMMs) for gas separation in the form of thick films were prepared via the combination of the polymer Matrimid^® 5218 and activated carbons (AC). The AC particles had a mean particle size of 1.5 μm and a [...] Read more.

In this work, mixed-matrix membranes (MMMs) for gas separation in the form of thick films were prepared via the combination of the polymer Matrimid^® 5218 and activated carbons (AC). The AC particles had a mean particle size of 1.5 μm and a mean pore diameter of 1.9 nm. The films were prepared by slow solvent evaporation from casting solutions in chloroform, which had a varying polymer–AC ratio. It was possible to produce stable films with up to a content of 50 vol % of AC. Thorough characterization experiments were accomplished via differential scanning calorimetry and thermogravimetric analysis, while the morphology of the MMMs was also investigated via scanning electron microscopy. The gas transport properties were revealed by employing time-lag measurements for different pure gases as well as sorption balance experiments for the filler particles. It was found that defect free Matrimid^® MMMs with AC were prepared and the increase of the filler content led to a higher effective permeability for different gases. The single gas selectivity α_ij of different gas pairs maintained stable values with the increase of AC content, regardless of the steep increase in the effective permeability of the pure gases. Estimation of the solubilities and the diffusivities of the Matrimid^®, AC, and MMMs allowed for the explanation of the increasing permeabilities of the MMMs, with the increase of AC content by modelling. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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12 pages, 3596 KiB

Open AccessArticle

Trifluoromethyl-Substituted Large Band-Gap Polytriphenylamines for Polymer Solar Cells with High Open-Circuit Voltages

by Shuwang Yi¹, Wanyuan Deng¹, Sheng Sun¹, Linfeng Lan¹, Zhicai He^1,*, Wei Yang¹ and Bin Zhang^1,2,*

¹ State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China

² Jiangsu Key Laboratory of Environmentally Friendly Polymeric Materials, School of Materials Science & Engineering, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou 213164, China

Polymers 2018, 10(1), 52; https://doi.org/10.3390/polym10010052 - 8 Jan 2018

Cited by 2 | Viewed by 4510

Abstract

Two large band-gap polymers (PTPACF and PTPA2CF) based on polytriphenylamine derivatives with the introduction of electron-withdrawing trifluoromethyl groups were designed and prepared by Suzuki polycondensation reaction. The chemical structures, thermal, optical and electrochemical properties were characterized in detail. From the UV-visible [...] Read more.

Two large band-gap polymers (PTPACF and PTPA2CF) based on polytriphenylamine derivatives with the introduction of electron-withdrawing trifluoromethyl groups were designed and prepared by Suzuki polycondensation reaction. The chemical structures, thermal, optical and electrochemical properties were characterized in detail. From the UV-visible absorption spectra, the PTPACF and PTPA2CF showed the optical band gaps of 2.01 and 2.07 eV, respectively. The cyclic voltammetry (CV) measurement displayed the deep highest occupied molecular orbital (HOMO) energy levels of −5.33 and −5.38 eV for PTPACF and PTPA2CF, respectively. The hole mobilities, determined by field-effect transistor characterization, were 2.5 × 10⁻³ and 1.1 × 10⁻³ cm² V⁻¹ S⁻¹ for PTPACF and PTPA2CF, respectively. The polymer solar cells (PSCs) were tested under the conventional device structure of ITO/PEDOT:PSS/polymer:PC₇₁BM/PFN/Al. All of the PSCs showed the high open circuit voltages (V_ocs) with the values approaching 1 V. The PTPACF and PTPA2CF based PSCs gave the power conversion efficiencies (PCEs) of 3.24% and 2.40%, respectively. Hence, it is a reliable methodology to develop high-performance large band-gap polymer donors with high V_ocs through the feasible side-chain modification. Full article

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

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16 pages, 5293 KiB

Open AccessArticle

Atmospheric Pressure Plasma Treatment for Grey Cotton Knitted Fabric

by Chi-wai Kan^* and Chui-fung Lam

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

Polymers 2018, 10(1), 53; https://doi.org/10.3390/polym10010053 - 8 Jan 2018

Cited by 34 | Viewed by 6274

Abstract

100% grey cotton knitted fabric contains impurities and yellowness and needs to be prepared for processing to make it suitable for coloration and finishing. Therefore, conventionally 100% grey cotton knitted fabric undergoes a process of scouring and bleaching, which involves the use of [...] Read more.

100% grey cotton knitted fabric contains impurities and yellowness and needs to be prepared for processing to make it suitable for coloration and finishing. Therefore, conventionally 100% grey cotton knitted fabric undergoes a process of scouring and bleaching, which involves the use of large amounts of water and chemicals, in order to remove impurities and yellowness. Due to increased environmental awareness, pursuing a reduction of water and chemicals is a current trend in textile processing. In this study, we explore the possibility of using atmospheric pressure plasma as a dry process to treat 100% grey cotton knitted fabric (single jersey and interlock) before processing. Experimental results reveal that atmospheric pressure plasma treatment can effectively remove impurities from 100% grey cotton knitted fabrics and significantly improve its water absorption property. On the other hand, if 100% grey cotton knitted fabrics are pretreated with plasma and then undergo a normal scouring process, the treatment time is reduced. In addition, the surface morphological and chemical changes in plasma-treated fabrics were studied and compared with the conventionally treated fabrics using scanning electron microscope (SEM), Fourier-transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The decrease in carbon content, as shown in XPS, reveal the removal of surface impurities. The oxygen-to-carbon (O/C) ratios of the plasma treated knitted fabrics reveal enhanced hydrophilicity. Full article

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

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11 pages, 2957 KiB

Open AccessArticle

Facile and Rapid Formation of Giant Vesicles from Glass Beads

by Radu Tanasescu¹

, Ute Mettal¹, Adai Colom^2,3, Aurélien Roux^2,3 and Andreas Zumbuehl^1,3,*

¹ Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland

² Department of Biochemistry, University of Geneva, 30, Quai Ernest-Ansermet, 1211 Geneva, Switzerland

³ National Centre of Competence in Research in Chemical Biology, 1211 Geneva, Switzerland

Polymers 2018, 10(1), 54; https://doi.org/10.3390/polym10010054 - 9 Jan 2018

Cited by 13 | Viewed by 7581

Abstract

Giant vesicles (GVs) are widely-used model systems for biological membranes. The formulation of these vesicles, however, can be problematic and artifacts, such as degraded molecules or left-over oil, may be present in the final liposomes. The rapid formulation of a high number of [...] Read more.

Giant vesicles (GVs) are widely-used model systems for biological membranes. The formulation of these vesicles, however, can be problematic and artifacts, such as degraded molecules or left-over oil, may be present in the final liposomes. The rapid formulation of a high number of artifact-free vesicles of uniform size using standard laboratory equipment is, therefore, highly desirable. Here, the gentle hydration method of glass bead-supported thin lipid films has been enhanced by adding a vortexing step. This led to the formulation of a uniform population of giant vesicles. Batches of glass beads coated with different lipids can be combined to produce vesicles of hybrid lipid compositions. This method represents a stable approach to rapidly generate giant vesicles. Full article

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

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12 pages, 5165 KiB

Open AccessArticle

Transparent Low Electrostatic Charge Films Based on Carbon Nanotubes and Polypropylene. Homopolymer Cast Films

by Zoe Vineth Quiñones-Jurado¹

, Miguel Ángel Waldo-Mendoza¹

, José Manuel Mata-Padilla²

, Pablo González-Morones³, Juan Guillermo Martínez-Colunga³, Florentino Soriano-Corral³

, Víctor Javier Cruz-Delgado^3,*

, Ronald Francis Ziolo³ and Carlos Alberto Avila-Orta^3,*

¹ Innovación y Desarrollo en Materiales Avanzados A.C., Grupo POLYnnova, Carr. San Luis Potosí-Guadalajara 1510, Nivel 3, Local 12, Lomas del Tecnológico, San Luis Potosí S.L.P. C.P. 78211, Mexico

² CONACyT—Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna H. 140, Col. San José de los Cerritos, Saltillo, Coahuila C.P. 25294, Mexico

³ Centro de Investigación en Química Aplicada, Blvd. Ing. Enrique Reyna H. 140, Col. San José de los Cerritos, Saltillo, Coahuila C.P. 25294, Mexico

Polymers 2018, 10(1), 55; https://doi.org/10.3390/polym10010055 - 9 Jan 2018

Cited by 6 | Viewed by 4022

Abstract

Use of multi-wall carbon nanotubes (MWCNTs) in external layers (A-layers) of ABA-trilayer polypropylene films was investigated, with the purpose of determining intrinsic and extrinsic factors that could lead to antistatic behavior of transparent films. The incorporation of 0.01, 0.1, and 1 wt % [...] Read more.

Use of multi-wall carbon nanotubes (MWCNTs) in external layers (A-layers) of ABA-trilayer polypropylene films was investigated, with the purpose of determining intrinsic and extrinsic factors that could lead to antistatic behavior of transparent films. The incorporation of 0.01, 0.1, and 1 wt % of MWCTNs in the A-layers was done by dilution through the masterbatch method. Masterbatches were fabricated using isotactic polypropylene (iPP) with different melt flow indexes 2.5, 34, and 1200 g/10 min, and using different ultrasound assist methods. It was found that films containing MWCNTs show surface electrical resistivity of 10¹² and 10¹⁶ Ω/sq, regardless of the iPP melt flow index (MFI) and masterbatch fabrication method. However, electrostatic charge was found to depend upon the iPP MFI, the ultrasound assist method and MWCNT concentration. A percolation electron transport mechanism was determined most likely responsible for this behavior. Optical properties for films containing MWCNTs do not show significant differences compared to the reference film at MWCNT concentrations below 0.1 wt %. However, an enhancement in brightness was observed, and it was attributed to ordered iPP molecules wrapping the MWCNTs. Bright transparent films with low electrostatic charge were obtained even for MWCNTs concentrations as low as 0.01 wt %. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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11 pages, 14441 KiB

Open AccessArticle

Influence of Temperature on the Mechanical Properties and Reactive Behavior of Al-PTFE under Quasi-Static Compression

by Huai-Xi Wang¹, Xiang Fang^1,*, Bin Feng², Zhen-Ru Gao¹, Shuang-Zhang Wu¹ and Yu-Chun Li^1,*

¹ College of Field Engineering, PLA Army Engineering University, Nanjing 210007, China

² China Huayin Ordnance Test Center, Huayin 714200, China

Polymers 2018, 10(1), 56; https://doi.org/10.3390/polym10010056 - 10 Jan 2018

Cited by 16 | Viewed by 6102

Abstract

Al-PTFE (aluminum-polytetrafluoroethylene) is a typical kind of Reactive Material (RM), which has a variety of potential applications in weapon systems. In this paper, quasi-static compression experiments were carried out for a pressed and sintered mixture of Al and PTFE powders using a microcomputer-controlled [...] Read more.

Al-PTFE (aluminum-polytetrafluoroethylene) is a typical kind of Reactive Material (RM), which has a variety of potential applications in weapon systems. In this paper, quasi-static compression experiments were carried out for a pressed and sintered mixture of Al and PTFE powders using a microcomputer-controlled electronic universal testing machine. The results show that both the mechanical property and reactive behavior of Al-PTFE are strongly temperature-dependent. The material undergoes a brittle-ductile transition associated with a temperature-induced crystalline phase transformation of the PTFE matrix. At low temperatures (−18, 0, and 16 °C), samples of Al-PTFE failed with shear crack and no reaction was observed. As the temperature increased (22, 35, and 80 °C), Al-PTFE exhibited a high toughness and violent reaction occurred in all of the tested samples. Scanning electron microscope observations showed different fracture mechanisms of the PTFE matrix and the increase in toughness was due to the formation of PTFE fibrils which could dissipate energy and bridge crack plane during plastic deformation. Full article

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

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14 pages, 4554 KiB

Open AccessArticle

Thermal, Mechanical and Optical Features of Aluminosilicate-Coated Cotton Textiles via the Crosslinking Method

by Alenka Ojstršek^*, Silvo Hribernik and Darinka Fakin

Institute of Engineering Materials and Design, Faculty of Mechanical Engineering, University of Maribor, 2000 Maribor, Slovenia

Polymers 2018, 10(1), 57; https://doi.org/10.3390/polym10010057 - 9 Jan 2018

Cited by 5 | Viewed by 5069

Abstract

The presented study focuses on the development of a pad-dry-thermofix functional coating process using a mixture of microporous aluminosilicate particles in diverse bath formulations to impart UV-ray-blocking, thermal stability and easy-care properties to the cotton fabric. The results of Scanning Electron Microscopy (SEM) [...] Read more.

The presented study focuses on the development of a pad-dry-thermofix functional coating process using a mixture of microporous aluminosilicate particles in diverse bath formulations to impart UV-ray-blocking, thermal stability and easy-care properties to the cotton fabric. The results of Scanning Electron Microscopy (SEM) and X-ray powder Diffraction (XRD) revealed the presence of three different types of zeolites within the examined sample, i.e., the largest amount being zeolite A, followed by the zeolite X, and the zeolite ZSM-5. The surface characterization results of zeolite-coated/cross-linked textiles provided evidence of acceptable UV-ray-blocking properties and increased thermal stability, as well as enhanced tensile strength and breaking tenacity without considerably decreasing the whiteness degree. Moreover, the dry crease recovery angle increased for the cotton fabric cross-linked via an mDMDHEU, and decreased significantly using 30 g/L zeolites negatively influencing qualitative values. TG/DTA results have proven the enlarged thermal stability of aluminosilicate-coated cotton, although combustion was not prevented. Full article

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

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17 pages, 4964 KiB

Open AccessArticle

Preparation and Characterization of Antibacterial Polypropylene Meshes with Covalently Incorporated β-Cyclodextrins and Captured Antimicrobial Agent for Hernia Repair

by Noor Sanbhal^1,2, Ying Mao¹, Gang Sun^1,3, Yan Li^1,*, Mazhar Peerzada² and Lu Wang^1,*

¹ Key Laboratory of Textile Science and Technology of Ministry of Education, Room 4023, College of Textiles, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620, China

² Department of Textile Engineering, Mehran University of Engineering and Technology, Jamshoro 76062, Sindh, Pakistan

³ Division of Textiles and Clothing, University of California, Davis, CA 95616, USA

Polymers 2018, 10(1), 58; https://doi.org/10.3390/polym10010058 - 11 Jan 2018

Cited by 23 | Viewed by 5089

Abstract

Polypropylene (PP) light weight meshes are commonly used as hernioplasty implants. Nevertheless, the growth of bacteria within textile knitted mesh intersections can occur after surgical mesh implantation, causing infections. Thus, bacterial reproduction has to be stopped in the very early stage of mesh [...] Read more.

Polypropylene (PP) light weight meshes are commonly used as hernioplasty implants. Nevertheless, the growth of bacteria within textile knitted mesh intersections can occur after surgical mesh implantation, causing infections. Thus, bacterial reproduction has to be stopped in the very early stage of mesh implantation. Herein, novel antimicrobial PP meshes grafted with β-CD and complexes with triclosan were prepared for mesh infection prevention. Initially, PP mesh surfaces were functionalized with suitable cold oxygen plasma. Then, hexamethylene diisocyanate (HDI) was successfully grafted on the plasma-activated PP surfaces. Afterwards, β-CD was connected with the already HDI reacted PP meshes and triclosan, serving as a model antimicrobial agent, was loaded into the cyclodextrin (CD) cavity for desired antibacterial functions. The hydrophobic interior and hydrophilic exterior of β-CD are well suited to form complexes with hydrophobic host guest molecules. Thus, the prepared PP mesh samples, CD-TCL-2 and CD-TCL-6 demonstrated excellent antibacterial properties against Staphylococcus aureus and Escherichia coli that were sustained up to 11 and 13 days, respectively. The surfaces of chemically modified PP meshes showed dramatically reduced water contact angles. Moreover, X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and Thermogravimetric (TGA) evidenced that there was no significant effect of grafted hexamethylene diisocyanate (HDI) and CD on the structural and thermal properties of the PP meshes. Full article

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

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16 pages, 6099 KiB

Open AccessArticle

Cross-Flow Catalysis Behavior of a PVDF/SiO₂@Ag Nanoparticles Composite Membrane

by Wenqiang Wang^1,2, Xi Chen^1,3,*

, Chu Zhao^1,3, Bowu Zhao^1,3, Hualin Dong^1,3, Shengkui Ma^1,3, Liying Li^1,2,*, Li Chen^1,3 and Bin Zhang⁴

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

² School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387, China

³ School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China

⁴ Tianjin BeiAo Membrane Co., Ltd., Tianjin 300180, China

Polymers 2018, 10(1), 59; https://doi.org/10.3390/polym10010059 - 10 Jan 2018

Cited by 11 | Viewed by 4662

Abstract

A blend of Polyvinylidene Fluoride (PVDF) and SiO₂ microspheres in N,N-Dimethylformamide (DMF) underwent phase inversion to form a PVDF/SiO₂ membrane with SiO₂ microspheres in the membrane’s pores. Subsequently, the SiO₂ microspheres have been used as platforms [...] Read more.

A blend of Polyvinylidene Fluoride (PVDF) and SiO₂ microspheres in N,N-Dimethylformamide (DMF) underwent phase inversion to form a PVDF/SiO₂ membrane with SiO₂ microspheres in the membrane’s pores. Subsequently, the SiO₂ microspheres have been used as platforms for in site Ag nanoparticles (NPs) synthesis, forming a composite membrane. Benefitting from the full exposure of Ag NPs to the reactants, the composite membrane shows high catalytic reactivity when catalyzing the reduction of p-nitrophenol under a cross-flow. The catalytic reaction follows the first-order kinetics, and the reaction rate increases with an increase in the amount of Ag NPs in the membrane, the reaction temperature, and the operating pressure. What is more, highly purified products can be produced and separated from the reactants in a timely manner by using the composite membrane. Full article

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

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18 pages, 7213 KiB

Open AccessArticle

Searching for Natural Conductive Fibrous Structures via a Green Sustainable Approach Based on Jute Fibers and Silver Nanoparticles

by Diana P. Ferreira^1,*, Armando Ferreira²

and Raul Fangueiro¹

¹ Centre for Textile Science and Technology (2C2T), University of Minho, 4800 Guimarães, Portugal

² Center of Physics, University of Minho, 4710-057 Braga, Portugal

Polymers 2018, 10(1), 63; https://doi.org/10.3390/polym10010063 - 11 Jan 2018

Cited by 32 | Viewed by 6551

Abstract

This paper provides new insights regarding jute fibers functionalization with silver nanoparticles (Ag NPs) with improved conductivity values and highlights the sustainability of the processes involved. These NPs were applied onto jute fabrics by two different sustainable methods: ultraviolet (UV) photoreduction and by [...] Read more.

This paper provides new insights regarding jute fibers functionalization with silver nanoparticles (Ag NPs) with improved conductivity values and highlights the sustainability of the processes involved. These NPs were applied onto jute fabrics by two different sustainable methods: ultraviolet (UV) photoreduction and by using polyethylene glycol (PEG) as a reducing agent and stabilizer. Field Emission Scanning Electron Microscopy (FESEM) images demonstrated that the Ag NPs were incorporated on the jute fibers surface by the two different approaches, with sizes ranging from 70 to 100 nm. Diffuse reflectance spectra revealed the plasmon absorption band, corresponding to the formation of metallic Ag NPs, in all samples under study. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) was used to characterize the obtained samples, demonstrating NPs adsorption to the surface of the fibers. The resistivity value obtained by the two-point probe method of the jute fabric without functionalization is about 1.5 × 10⁷ Ω·m, whereas, after NPs functionalization, it decreased almost 15,000 times, reaching a value of 1.0 × 10³ Ω·m. Further research work is being undertaken for improving these values, however, 1000 Ω·m of resistivity (conductivity = 0.001 S/m) is already a very reasonable value when compared with those obtained with other developed systems based on natural fibers. In summary, this work shows that the use of very simple methodologies enabled the functionalization of jute fibers with reasonable values of conductivity. This achievement has a huge potential for use in smart textile composites. Full article

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

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11 pages, 4073 KiB

Open AccessArticle

A Molecular Dynamics Study of Crosslinked Phthalonitrile Polymers: The Effect of Crosslink Density on Thermomechanical and Dielectric Properties

by Janel Chua¹ and Qingsong Tu^2,*

¹ DSO National Laboratories, Singapore 118225, Singapore

² Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA

Polymers 2018, 10(1), 64; https://doi.org/10.3390/polym10010064 - 11 Jan 2018

Cited by 23 | Viewed by 9641

Abstract

In this work, molecular dynamics (MD) and molecular mechanics (MM) simulations are used to study well-equilibrated models of 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPh)–1,3-bis(3-aminophenoxy)benzene (m-APB) phthalonitrile (PN) system with a range of crosslink densities. A cross-linking technique is introduced to build a series of systems with different [...] Read more.

In this work, molecular dynamics (MD) and molecular mechanics (MM) simulations are used to study well-equilibrated models of 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPh)–1,3-bis(3-aminophenoxy)benzene (m-APB) phthalonitrile (PN) system with a range of crosslink densities. A cross-linking technique is introduced to build a series of systems with different crosslink densities; several key properties of this material, including thermal expansion, mechanical properties and dielectric properties are studied and compared with experimental results. It is found that the coefficient of linear thermal expansion predicted by the model is in good agreement with experimental results and indicative of the good thermal stability of the PN polymeric system. The simulation also shows that this polymer has excellent mechanical property, whose strength increases with increasing crosslink density. Lastly and most importantly, the calculated dielectric constant—which shows that this polymer is an excellent insulating material—indicates that there is an inverse relation between cross-linking density and dielectric constant. The trend gave rise to an empirical quadratic function which can be used to predict the limits of attainable dielectric constant for highly crosslinked polymer systems. The current computational work provides strong evidence that this polymer is a promising material for aerospace applications and offers guidance for experimental studies of the effect of cross-linking density on the thermal, mechanical and dielectric properties of the material. Full article

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7 pages, 2548 KiB

Open AccessArticle

Gold Nanospheres Dispersed Light Responsive Epoxy Vitrimers

by Zhenhua Wang, Zhen Li, Yen Wei^* and Yan Ji^*

The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China

Polymers 2018, 10(1), 65; https://doi.org/10.3390/polym10010065 - 11 Jan 2018

Cited by 31 | Viewed by 5723

Abstract

Vitrimers represent a new class of smart materials. They are covalently crosslinked like thermosets, yet they can be reprocessed like thermoplastics. The underlying mechanism is the rapid exchange reactions which form new bonds while breaking the old ones. So far, heating is the [...] Read more.

Vitrimers represent a new class of smart materials. They are covalently crosslinked like thermosets, yet they can be reprocessed like thermoplastics. The underlying mechanism is the rapid exchange reactions which form new bonds while breaking the old ones. So far, heating is the most widely used stimulus to activate the exchange reaction. Compared to heating, light not only is much more convenient to achieve remote and regional control, but can also offer fast healing. Gold nanospheres are excellent photothermal agents, but they are difficult to disperse into vitrimers as they easily aggregate. In this paper, we use polydopamine to prepare gold nanospheres. The resultant polydopamine-coated gold nanospheres (GNS) can be well dispersed into epoxy vitrimers, endowing epoxy vitrimers with light responsivity. The composites can be reshaped permanently and temporarily with light at different intensity. Efficient surface patterning and healing are also demonstrated. Full article

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

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14 pages, 5150 KiB

Open AccessArticle

Assessing the Contribution of the CFRP Strip of Bearing the Applied Load Using Near-Surface Mounted Strengthening Technique with Innovative High-Strength Self-Compacting Cementitious Adhesive (IHSSC-CA)

by Alyaa Mohammed^1,*

, Nihad T. K. Al-Saadi² and Riadh Al-Mahaidi²

¹ Centre for Sustainable Infrastructure, Faculty of Science, Engineering and Technology, Swinburne University of Technology, P.O. Box 218, Melbourne, VIC 3122, Australia

² Department of Civil and Construction Engineering, Faculty of Science, Engineering and Technology, Swinburne University of Technology, P.O. Box 218, Melbourne, VIC 3122, Australia

Polymers 2018, 10(1), 66; https://doi.org/10.3390/polym10010066 - 11 Jan 2018

Cited by 9 | Viewed by 4256

Abstract

Efficient transfer of load between concrete substrate and fibre reinforced polymer (FRP) by the bonding agent is the key factor in any FRP strengthening system. An innovative high-strength self-compacting non-polymer cementitious adhesive (IHSSC-CA) was recently developed by the authors and has been used [...] Read more.

Efficient transfer of load between concrete substrate and fibre reinforced polymer (FRP) by the bonding agent is the key factor in any FRP strengthening system. An innovative high-strength self-compacting non-polymer cementitious adhesive (IHSSC-CA) was recently developed by the authors and has been used in a number of studies. Graphene oxide and cementitious materials are used to synthesise the new adhesive. The successful implementation of IHSSC-CA significantly increases carbon FRP (CFRP) strip utilization and the load-bearing capacity of the near-surface mounted (NSM) CFRP strengthening system. A number of tests were used to inspect the interfacial zone in the bonding area of NSM CFRP strips, including physical examination, pore structure analysis, and three-dimensional laser profilometery analysis. It was deduced from the physical inspection of NSM CFRP specimens made with IHSSC-CA that a smooth surface for load transfer was found in the CFRP strip without stress concentrations in some local regions. A smooth surface of the adhesive layer is very important for preventing localized brittle failure in the concrete. The pore structure analysis also confirmed that IHSSC-CA has better composite action between NSM CFRP strips and concrete substrate than other adhesives, resulting in the NSM CFRP specimens made with IHSSC-CA sustaining a greater load. Finally, the results of three-dimensional laser profilometery revealed a greater degree of roughness and less deformation on the surface of the CFRP strip when IHSSC-CA was used compared to other adhesives. Full article

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

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13 pages, 1546 KiB

Open AccessArticle

The Influence of Chemically Modified Potato Maltodextrins on Stability and Rheological Properties of Model Oil-in-Water Emulsions

by Karolina Pycia¹, Artur Gryszkin², Wiktor Berski³ and Lesław Juszczak^4,*

¹ Department of Food Technology and Human Nutrition, University of Rzeszow, Zelwerowicza 4 Str., 35-601 Rzeszow, Poland

² Department of Food Storage and Technology, Wroclaw University of Environmental and Life Sciences, Chełmońskiego 37 Str., 51-630 Wroclaw, Poland

³ Department of Carbohydrates Technology, University of Agriculture in Krakow, Balicka 122 Str., 30-149 Krakow, Poland

⁴ Department of Food Analysis and Evaluation of Food Quality, University of Agriculture in Krakow, Balicka 122 Str., 30-149 Krakow, Poland

Polymers 2018, 10(1), 67; https://doi.org/10.3390/polym10010067 - 13 Jan 2018

Cited by 14 | Viewed by 5404

Abstract

The aim of this study was to determine the effect of the maltodextrins prepared from chemically modified starches (crosslinked, stabilized, crosslinked and stabilized) on the stability and rheological properties of model oil-in-water (o/w) emulsions. Based on the obtained results, it was concluded that [...] Read more.

The aim of this study was to determine the effect of the maltodextrins prepared from chemically modified starches (crosslinked, stabilized, crosslinked and stabilized) on the stability and rheological properties of model oil-in-water (o/w) emulsions. Based on the obtained results, it was concluded that emulsion stability depended on hydrolysates dextrose equivalent (DE) value. Maltodextrin with the lowest degree of depolymerization effectively stabilized the dispersed system, and the effectiveness of this action depended on the maltodextrin type and concentration. Addition of distarch phosphate-based maltodextrin stabilized emulsion at the lowest applied concentration, and the least effective was maltodextrin prepared from acetylated starch. Emulsions stabilized by maltodextrins (DE 6) prepared from distarch phosphate and acetylated distarch adipate showed the predominance of the elastic properties over the viscous ones. Only emulsion stabilized by maltodextrin prepared from distarch phosphate (E1412) revealed the properties of strong gel. Additionally, the decrease in emulsions G′ and G″ moduli values, combined with an increase in the value of DE maltodextrins, was observed. Full article

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10 pages, 3067 KiB

Open AccessArticle

Photoinduced Cu(II)-Mediated RDRP to P(VDF-co-CTFE)-g-PAN

by Xin Hu^1,4

, Guopeng Cui^2,4, Ning Zhu^2,4

, Jinglin Zhai^2,4 and Kai Guo^2,3,4,*

¹ College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, China

² College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China

³ State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211800, China

⁴ Jiangsu National Synergetic Innovation Centre for Advance Materials, Nanjing Tech University, Nanjing 211800, China

Polymers 2018, 10(1), 68; https://doi.org/10.3390/polym10010068 - 13 Jan 2018

Cited by 15 | Viewed by 5318

Abstract

Photoinduced Cu(II)-mediated reversible deactivation radical polymerization (RDRP) was employed to synthesize poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-polyacrylonitrile (P(VDF-co-CTFE)-g-PAN). The concentration of copper catalyst (CuCl₂) loading was as low as 1/64 equivalent to chlorine atom in the presence [...] Read more.

Photoinduced Cu(II)-mediated reversible deactivation radical polymerization (RDRP) was employed to synthesize poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-polyacrylonitrile (P(VDF-co-CTFE)-g-PAN). The concentration of copper catalyst (CuCl₂) loading was as low as 1/64 equivalent to chlorine atom in the presence of Me₆-Tren under UV irradiation. The light-responsive nature of graft polymerization was confirmed by “off-on” impulsive irradiation experiments. Temporal control of the polymerization process and varied graft contents were achieved via this photoinduced Cu(II)-mediated RDRP. Full article

(This article belongs to the Special Issue Fluorinated Polymers)

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23 pages, 3900 KiB

Open AccessArticle

Effect of the Configuration of a Bulky Aluminum Initiator on the Structure of Copolymers of l,l-Lactide with Symmetric Comonomer Trimethylene Carbonate

by Marta Socka^*, Ryszard Szymanski^*

, Stanislaw Sosnowski and Andrzej Duda^†

¹ Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Lodz, Sienkiewicza 112, Poland

^† Deceased.

Polymers 2018, 10(1), 70; https://doi.org/10.3390/polym10010070 - 13 Jan 2018

Cited by 4 | Viewed by 4290

Abstract

The effect of configuration of an asymmetric bulky initiator 2,2′-[1,1′-binaphtyl-2,2′-diyl- bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide (Ini) on structure of copolymer of asymmetric monomer l,l-lactide (Lac) with symmetric comonomer trimethylene carbonate (Tmc) was studied using polarimetry, dilatometry, [...] Read more.

The effect of configuration of an asymmetric bulky initiator 2,2′-[1,1′-binaphtyl-2,2′-diyl- bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide (Ini) on structure of copolymer of asymmetric monomer l,l-lactide (Lac) with symmetric comonomer trimethylene carbonate (Tmc) was studied using polarimetry, dilatometry, Size Exclusion Chromatography (SEC), and Carbon Nuclear Magnetic Resonance (¹³C NMR). When the S-enantiomer of Ini was used the distribution in copolymer chains at the beginning of polymerization is statistical, with alternacy tendency, changing next through a gradient region to homoblocks of Tmc. However, when R-Ini was used, the product formed was a gradient oligoblock one, with Tmc blocks prevailing at the beginning, changing to Lac blocks dominating at the end part of chains. Initiation of copolymerization with the mixture of both initiator enantiomers (S:R = 6:94) gave a multiblock copolymer of similar features but shorter blocks. Analysis of copolymerization progress required complex analysis of dilatometric data, assuming different molar volume contraction coefficients for units located in different triads. Comonomer reactivity ratios of studied copolymerizations were determined. Full article

(This article belongs to the Special Issue Polymerization Kinetics)

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13 pages, 3426 KiB

Open AccessArticle

A Natural Antibacterial-Antioxidant Film from Soy Protein Isolate Incorporated with Cortex Phellodendron Extract

by Shumin Liang^1,2 and Lijuan Wang^1,2,*

¹ Key Laboratory of Bio-Based Materials Science and Technology of Ministry of Education, Northeast Forestry University, Harbin 150040, China

² Research Center of Wood Bionic Intelligent Science, Northeast Forestry University, Harbin 150040, China

Polymers 2018, 10(1), 71; https://doi.org/10.3390/polym10010071 - 13 Jan 2018

Cited by 64 | Viewed by 6534

Abstract

An active film was prepared by incorporating cortex Phellodendron extract (CPE, an active agent) into a soybean protein isolate (SPI). Different concentrations of CPE (0%, 10%, 12.5%, 15%, 17.5%, 20%, or 22.5%, w/w, based on SPI) were mixed into the [...] Read more.

An active film was prepared by incorporating cortex Phellodendron extract (CPE, an active agent) into a soybean protein isolate (SPI). Different concentrations of CPE (0%, 10%, 12.5%, 15%, 17.5%, 20%, or 22.5%, w/w, based on SPI) were mixed into the films characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetry, tensile tests, and barrier properties. The rheological properties of the solutions were also tested. The effects of the CPE content on the antibacterial and antioxidant activities of the films were examined. The results indicated that new hydrogen bonds formed between molecules in the films, and the crystallinity of the films decreased. The incorporation of CPE had no significant influence on the thermal stability of the films. Films containing 15% CPE had the maximum tensile strength of 6.00 MPa. The barrier properties against water vapor, oxygen, and light enhanced with the incorporation of CPE. The antioxidant activity of the SPI film was also improved. The films were effective against Staphylococcus aureus (S. aureus, Gram-positive bacteria). These results suggest that the SPI/CPE film can potentially extend the shelf lives of foods. Full article

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

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12 pages, 2750 KiB

Open AccessArticle

Colloidal Dispersion of a Perfluorosulfonated Ionomer in Water–Methanol Mixtures

by Sinan Li, Ken Terao

and Takahiro Sato^*

Department of Macromolecular Science, Osaka University, Toyonaka Osaka 560-0043, Japan

Polymers 2018, 10(1), 72; https://doi.org/10.3390/polym10010072 - 14 Jan 2018

Cited by 11 | Viewed by 4796

Abstract

We have investigated the dispersion state of a perfluorosulfonated ionomer (PFSI; Nafion^®) in aqueous dispersion and the effect of methanol (MeOH) added to the aqueous dispersion by small-angle X-ray scattering (SAXS) as well as static and dynamic light scattering (SLS and [...] Read more.

We have investigated the dispersion state of a perfluorosulfonated ionomer (PFSI; Nafion^®) in aqueous dispersion and the effect of methanol (MeOH) added to the aqueous dispersion by small-angle X-ray scattering (SAXS) as well as static and dynamic light scattering (SLS and DLS, respectively). Although both electrostatic and hydrophobic interactions of PFSI are expected to be strong in the dispersions, SAXS profiles obtained were satisfactorily fitted by the spherical particle model of a bimodal molar mass distribution. The rod-like aggregate model proposed in previous papers was denied at least for the present PFSI dispersion. Although the SAXS profiles exhibited a weak peak and the auto-correlation functions of DLS showed a log-time decay by the “repulsive cage effect” due to the long-ranged electrostatic interaction among PFSI particles, the concentration dependence of SLS results was probably normal because the cancellation of the electrostatic and hydrophobic interactions. The addition of MeOH into the aqueous dispersion of PFSI weakened both the hydrophobic and electcrostatic interactions of PFSI, and it is rather difficult to classify whether MeOH is a good or poor solvent (dispersant) for PFSI. Full article

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13 pages, 1554 KiB

Open AccessArticle

Theory of the Flower Micelle Formation of Amphiphilic Random and Periodic Copolymers in Solution

by Takahiro Sato

Department of Macromolecular Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan

Polymers 2018, 10(1), 73; https://doi.org/10.3390/polym10010073 - 14 Jan 2018

Cited by 8 | Viewed by 6853

Abstract

The mixing Gibbs energy Δg_m for the flower-micelle phase of amphiphilic random and periodic (including alternating) copolymers was formulated on the basis of the lattice model. The formulated Δg_m predicts (1) the inverse proportionality of the aggregation number to [...] Read more.

The mixing Gibbs energy Δg_m for the flower-micelle phase of amphiphilic random and periodic (including alternating) copolymers was formulated on the basis of the lattice model. The formulated Δg_m predicts (1) the inverse proportionality of the aggregation number to the degree of polymerization of the copolymer, (2) the increase of the critical micelle concentration with decreasing the hydrophobe content, and (3) the crossover from the micellization to the liquid–liquid phase separation as the hydrophobe content increases. The transition from the uni-core flower micelle to the multi-core flower necklace as the degree of polymerization increases was also implicitly indicated by the theory. These theoretical results were compared with experimental results for amphiphilic random and alternating copolymers reported so far. Full article

(This article belongs to the Special Issue Polymer Micelles)

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15 pages, 3763 KiB

Open AccessArticle

Bleomycin-Loaded pH-Sensitive Polymer–Lipid-Incorporated Liposomes for Cancer Chemotherapy

by Eiji Yuba^1,*

, Tomohiro Osaki^2,*, Misato Ono², Shinjae Park¹, Atsushi Harada¹, Masamichi Yamashita², Kazuo Azuma², Takeshi Tsuka², Norihiko Ito², Tomohiro Imagawa² and Yoshiharu Okamoto²

¹ Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan

² Joint Department of Veterinary Clinical Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan

Polymers 2018, 10(1), 74; https://doi.org/10.3390/polym10010074 - 15 Jan 2018

Cited by 41 | Viewed by 8290

Abstract

Cancer chemotherapeutic systems with high antitumor effects and less adverse effects are eagerly desired. Here, a pH-sensitive delivery system for bleomycin (BLM) was developed using egg yolk phosphatidylcholine liposomes modified with poly(ethylene glycol)-lipid (PEG-PE) for long circulation in the bloodstream and 2-carboxycyclohexane-1-carboxylated polyglycidol-having [...] Read more.

Cancer chemotherapeutic systems with high antitumor effects and less adverse effects are eagerly desired. Here, a pH-sensitive delivery system for bleomycin (BLM) was developed using egg yolk phosphatidylcholine liposomes modified with poly(ethylene glycol)-lipid (PEG-PE) for long circulation in the bloodstream and 2-carboxycyclohexane-1-carboxylated polyglycidol-having distearoyl phosphatidylethanolamine (CHexPG-PE) for pH sensitization. The PEG-PE/CHexPG-PE-introduced liposomes showed content release responding to pH decrease and were taken up by tumor cells at a rate 2.5 times higher than that of liposomes without CHexPG-PE. BLM-loaded PEG-PE/CHexPG-PE-introduced liposomes exhibited comparable cytotoxicity with that of the free drug. Intravenous administration of these liposomes suppressed tumor growth more effectively in tumor-bearing mice than did the free drug and liposomes without CHexPG-PE. However, at a high dosage of BLM, these liposomes showed severe toxicity to the spleen, liver, and lungs, indicating the trapping of liposomes by mononuclear phagocyte systems, probably because of recognition of the carboxylates on the liposomes. An increase in PEG molecular weight on the liposome surface significantly decreased toxicity to the liver and spleen, although toxicity to the lungs remained. Further improvements such as the optimization of PEG density and lipid composition and the introduction of targeting ligands to the liposomes are required to increase therapeutic effects and to reduce adverse effects. Full article

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

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12 pages, 11746 KiB

Open AccessArticle

Mechanical Properties and Wear Resistance of Sulfonated Graphene/Waterborne Polyurethane Composites Prepared by In Situ Method

by Jianyan Feng^1,2, Xuechuan Wang^1,2,*, Peiying Guo³, Yujie Wang^1,2 and Xiaomin Luo^1,2

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

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

³ School of Arts and Sciences, Shanxi University of Science & Technology, Xi’an 710021, Shanxi, China

Polymers 2018, 10(1), 75; https://doi.org/10.3390/polym10010075 - 15 Jan 2018

Cited by 25 | Viewed by 5531

Abstract

In order to improve the dispensability of graphene oxide (GO) in waterborne polyurethane (WPU), sulfonated graphene (SGO) with superior dispersity was prepared by modifying graphene oxide with sodium 2-chloroethane sulfonate to introduce hydrophilic sulfonic groups into the structure. SGO/WPU composites were prepared using [...] Read more.

In order to improve the dispensability of graphene oxide (GO) in waterborne polyurethane (WPU), sulfonated graphene (SGO) with superior dispersity was prepared by modifying graphene oxide with sodium 2-chloroethane sulfonate to introduce hydrophilic sulfonic groups into the structure. SGO/WPU composites were prepared using isophorone diisocyanate (IPDI), polytetramethylene ether glycol (PTMEG 2000), dimethylolpropionic acid (DMPA) and SGO as raw materials. The influence of SGO content on composite properties were investigated. The structure and morphology of SGO and SGO/WPU composites were characterized by infrared spectroscopy, X-ray diffractometry and transmission electron microscopy etc. Their mechanical properties and wear resistance were analyzed as well. The experimental results showed that SGO was successfully grafted onto polyurethane macromolecule by an in situ method and, with the introduction of sulfonic groups, the interfacial compatibility of GO and PU was improved significantly so that SGO evenly dispersed into WPU. The SGO that was grafted onto WPU macromolecules exhibited layered morphology with nanometers in the WPU matrix. With increasing SGO content, the tensile strength and the wear resistance of the film increased, but the addition of more than 0.8 wt % SGO yielded unfavorable results. When the added amount of SGO was 0.8 wt % of WPU, the tensile strength of the composite film was 46.53% higher than that of the blank group, and the wear resistance of the film was remarkably improved, which was due to a strong interaction between the SGO and WPU phases. Thus, the conclusion can be drawn that appropriate amount of SGO addition can enhance the mechanical properties of SGO/WPU composite film. Full article

(This article belongs to the Special Issue Applications of Graphene and Fullerene Nanocomposites)

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18 pages, 8877 KiB

Open AccessArticle

A Comparative Study on Micellar and Solubilizing Behavior of Three EO-PO Based Star Block Copolymers Varying in Hydrophobicity and Their Application for the In Vitro Release of Anticancer Drugs

by Bijal Vyas¹, Sadafara A. Pillai¹, Anita Bahadur² and Pratap Bahadur^1,*

¹ Department of Chemistry, Veer Narmad South Gujarat University, Surat 395007, India

² Department of Zoology, PT Sarvajanik College of Science, Surat 395001, India

Polymers 2018, 10(1), 76; https://doi.org/10.3390/polym10010076 - 15 Jan 2018

Cited by 25 | Viewed by 7078

Abstract

The temperature and pH dependent self-assembly of three star shaped ethylene oxide-propylene oxide (EO-PO) block copolymers (Tetronics^® 304, 904 and 908) with widely different hydrophobicity was examined in aqueous solutions. Physico-chemical methods viz. viscosity, cloud point, solubilization along with thermal, scattering and [...] Read more.

The temperature and pH dependent self-assembly of three star shaped ethylene oxide-propylene oxide (EO-PO) block copolymers (Tetronics^® 304, 904 and 908) with widely different hydrophobicity was examined in aqueous solutions. Physico-chemical methods viz. viscosity, cloud point, solubilization along with thermal, scattering and spectral techniques shows strongly temperature and salt dependent solution behavior. T304 possessing low molecular weight did not form micelles; moderately hydrophilic T904 remained as micelles at ambient temperature and showed micellar growth while very hydrophilic T908 formed micelles at elevated temperatures. The surface activity/micellization/solubilization power was favored in the presence of salt. The copolymers turn more hydrophilic in acidic pH due to protonation of central ethylene diamine moiety that hinders micelle formation. The solubilization of a model insoluble azo dye 1-(o-Tolylazo)-2-naphthol (Orange OT) and hydrophobic drugs (quercetin and curcumin) for copolymer solutions in aqueous and salt solutions are also reported. Among the three copolymers, T904 showed maximum solubility of dye and drugs, hence the in vitro release of drugs from T904 micelles was estimated and the effect on cytotoxicity of loading the drugs in T904 micelles was compared with the cytotoxicity of free drugs on the CHO-K1 cells. The results from the present work provide a better insight in selection of Tetronics^® for their application in different therapeutic applications. Full article

(This article belongs to the Special Issue Polymer Micelles)

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17 pages, 15625 KiB

Open AccessArticle

EBR Strengthening Technique for Concrete, Long-Term Behaviour and Historical Survey

by Christoph Czaderski^*

and Urs Meier

Swiss Federal Laboratories for Materials Science and Technology (Empa), Überlandstrasse 129, 8600 Dübendorf, Switzerland

Polymers 2018, 10(1), 77; https://doi.org/10.3390/polym10010077 - 17 Jan 2018

Cited by 20 | Viewed by 6503

Abstract

Epoxy bonded steel plates (externally bonded reinforcemen: EBR) for the strengthening of concrete structures were introduced to the construction industry in the late 1960s, and the use of fibre reinforced polymers (FRPs) was introduced in the 1990s, which means that these techniques have [...] Read more.

Epoxy bonded steel plates (externally bonded reinforcemen: EBR) for the strengthening of concrete structures were introduced to the construction industry in the late 1960s, and the use of fibre reinforced polymers (FRPs) was introduced in the 1990s, which means that these techniques have already been used in construction for 50 and 25 years, respectively. In the first part of the paper, a historical survey of the development and introduction of these strengthening techniques into the construction industry are presented. The monitoring of such applications in construction is very important and gives more confidence to this strengthening technique. Therefore, in the second part of the paper, two long-term monitoring campaigns over an extraordinarily long duration will be presented. Firstly, a 47-year monitoring campaign on a concrete beam with an epoxy bonded steel plate and, secondly, a 20-year monitoring campaign on a road bridge with epoxy bonded CFRP (carbon fibre reinforced polymers) strips are described. The paper is an expanded version of the paper presented at the SMAR2017 Conference. Full article

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

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25 pages, 1341 KiB

Open AccessArticle

Microphase Segregation of Diblock Copolymers Studied by the Self-Consistent Field Theory of Scheutjens and Fleer

by Merve Mocan

, Marleen Kamperman and Frans A. M. Leermakers^*

Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands

Polymers 2018, 10(1), 78; https://doi.org/10.3390/polym10010078 - 17 Jan 2018

Cited by 8 | Viewed by 5903

Abstract

We used the self-consistent field (SCF) formalism of Scheutjens and Fleer (SF-SCF) to complement existing theoretical investigations on the phase behavior of block copolymer melts. This method employs the freely jointed chain (FJC) model for finite chain length and systematic differences exist compared [...] Read more.

We used the self-consistent field (SCF) formalism of Scheutjens and Fleer (SF-SCF) to complement existing theoretical investigations on the phase behavior of block copolymer melts. This method employs the freely jointed chain (FJC) model for finite chain length and systematic differences exist compared to the classical SCF predictions. We focus on the critical and hexagonal (HEX) to lamellar (LAM) phase transition region at intermediate and strong segregations. Chain length (N) dependence of the critical point (

χ^{c r}

) was found to be

χ^{c r} N = 10.495 (1 + 4 / N)

. The characteristic spacing (D) of LAM was found as

D = 4 / 3 \sqrt{N}

at the critical conditions. We present SF-SCF predictions for the phases single gyroid (SG), double gyroid (DG) and hexagonally perforated lamellar (HPL), in the region where HEX and LAM compete. At

χ N = 30

,

N = 300

; we found SG and HPL were metastable with respect to LAM or HEX, DG was stable in a narrow region of the asymmetry ratio. In contrast to the latest predictions, at strong segregation

χ N = 120

, DG was found to be metastable. From the structural evolution of HPL, we speculate that this may be an intermediate phase that allows the system to go through various connectivity regimes between minority and majority blocks. Full article

(This article belongs to the Special Issue RAFT Living Radical Polymerization and Self-Assembly)

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18 pages, 2757 KiB

Open AccessArticle

Antimicrobial Carvacrol-Containing Polypropylene Films: Composition, Structure and Function

by Max Krepker¹, Ofer Prinz-Setter¹, Rotem Shemesh², Anita Vaxman², David Alperstein³ and Ester Segal^1,4,*

¹ Department of Biotechnology and Food Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel

² Carmel Olefins Ltd., P.O. Box 1468, Haifa 31014, Israel

³ Department of Mechanical Engineering, Ort Braude College, P.O. Box 78, Karmiel 2161002, Israel

⁴ The Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel

Polymers 2018, 10(1), 79; https://doi.org/10.3390/polym10010079 - 16 Jan 2018

Cited by 55 | Viewed by 8103

Abstract

Significant research has been directed toward the incorporation of bioactive plant extracts or essential oils (EOs) into polymers to endow the latter with antimicrobial functionality. EOs offer a unique combination of having broad antimicrobial activity from a natural source, generally recognized as safe [...] Read more.

Significant research has been directed toward the incorporation of bioactive plant extracts or essential oils (EOs) into polymers to endow the latter with antimicrobial functionality. EOs offer a unique combination of having broad antimicrobial activity from a natural source, generally recognized as safe (GRAS) recognition in the US, and a volatile nature. However, their volatility also presents a major challenge in their incorporation into polymers by conventional high-temperature-processing techniques. Herein, antimicrobial polypropylene (PP) cast films were produced by incorporating carvacrol (a model EO) or carvacrol, loaded into halloysite nanotubes (HNTs), via melt compounding. We studied the composition-structure-property relationships in these systems, focusing on the effect of carvacrol on the composition of the films, the PP crystalline phase and its morphology and the films’ mechanical and antimicrobial properties. For the first time, molecular dynamics simulations were applied to reveal the complex interactions between the components of these carvacrol-containing systems. We show that strong molecular interactions between PP and carvacrol minimize the loss of this highly-volatile EO during high-temperature polymer processing, enabling semi-industrial scale production. The resulting films exhibit outstanding antimicrobial properties against model microorganisms (Escherichia coli and Alternaria alternata). The PP/(HNTs-carvacrol) nanocomposite films, containing the carvacrol-loaded HNTs, display a higher level of crystalline order, superior mechanical properties and prolonged release of carvacrol, in comparison to PP/carvacrol blends. These properties are ascribed to the role of HNTs in these nanocomposites and their effect on the PP matrix and retained carvacrol content. Full article

(This article belongs to the Special Issue Antimicrobial Polymers)

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10 pages, 2113 KiB

Open AccessArticle

Accurately Determining the Extent of Coupling in Post Polymerization Reactions of Polystyrene

by Ching Pan and Eric Tillman^*

Department of Chemistry and Biochemistry, Santa Clara University, 500 El Camino Real, Santa Clara, CA 95053, USA

Polymers 2018, 10(1), 80; https://doi.org/10.3390/polym10010080 - 16 Jan 2018

Cited by 3 | Viewed by 5773

Abstract

Polymers prepared by controlled radical polymerization (CRP) can be employed in subsequent chain-end joining reactions, yet accurately assessing the extent of coupling in mechanistically unique paths is not straightforward. Precisely known mixtures of polystyrene standards were prepared and analyzed by gel permeation chromatography [...] Read more.

Polymers prepared by controlled radical polymerization (CRP) can be employed in subsequent chain-end joining reactions, yet accurately assessing the extent of coupling in mechanistically unique paths is not straightforward. Precisely known mixtures of polystyrene standards were prepared and analyzed by gel permeation chromatography (GPC), mimicking the coupled product and precursor that could be present after a post-polymerization, chain-end joining reaction. The exactly known percentages of each polymer in the mixture allowed for comparison of the true “extent of coupling” (X_c) to that determined by a commonly used equation, which is based on number average molecular weights (M_n) of the precursor and coupled product. The results indicated that an improvement in accuracy could be achieved by instead using refractive index (RI) signal height ratios under the peak molecular weight (M_p) of each component, with all calculations being within 0.05 of the true X_c of the fabricated “product” mixture (compared to greater than 0.10 average error using the more established method) when the sample mixture had nominal molecular weights of 2500 and 5000 Da. Moreover, when “precursor” and “coupled” pairs mixed were not related as a simple doubling of molecular weight, the calculation method presented here remained effective at determining the content of the mixture, especially at higher X_c values (>0.45). This second case is important for experiments that may link polymer chains together with a spacer, such as a radical trap, a triazole, or even larger structure such as an oligomer. Full article

(This article belongs to the Special Issue Living Polymerization)

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12 pages, 4003 KiB

Open AccessArticle

Suitability of Different Variants of Polyethylene Glycol Impregnation for the Dimensional Stabilization of Oak Wood

by Tillmann Meints^1,*, Christan Hansmann¹ and Wolfgang Gindl-Altmutter^1,2

¹ Wood K Plus—Competence Centre for Wood Composites and Wood Chemistry, Altenberger Stasse 69, 4040 Linz, Austria

² Department of Material Science and Process Engineering, Institute of Wood Technology and Renewable Materials, University of Natural Resources and Life Science (BOKU), Konrad Lorenzstrasse 24, 3430 Tulln, Austria

Polymers 2018, 10(1), 81; https://doi.org/10.3390/polym10010081 - 16 Jan 2018

Cited by 37 | Viewed by 6646

Abstract

The common method to impregnate wood with polyethylene glycol (PEG) is to store the samples for several weeks in aqueous PEG-solution, allowing for diffusion of PEG into the wood. As this method is poorly suited for industrial application, an alternative approach based on [...] Read more.

The common method to impregnate wood with polyethylene glycol (PEG) is to store the samples for several weeks in aqueous PEG-solution, allowing for diffusion of PEG into the wood. As this method is poorly suited for industrial application, an alternative approach based on vacuum-pressure treatment is evaluated in the present study. Using European oak wood and three variants of PEG, including silane-functionalized PEG, impregnation experiments at different PEG concentrations were performed. Significant uptake of PEG resulted in clearly altered wood-water relations and improved dimensional stability of oak wood. These results are discussed in terms of stability in humid and aqueous environments, and in terms of effects of the anatomy of oak wood on differences in dimensional stabilization observed along the radial and tangential anatomical directions, respectively. While both of the PEG variants perform better with an anti-shrinkage efficiency of up to 80%, the PEG-silane variant performs less effectively in this respect; however PEG-silane is clearly predominant in case of water extraction. Full article

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16 pages, 5750 KiB

Open AccessArticle

Electrical, Mechanical and Electromechanical Properties of Graphene-Thermoset Polymer Composites Produced Using Acetone-DMF Solvents

by Alessandro Giuseppe D’Aloia^1,2,*

, Alessandro Proietti^1,2, Hossein Cheraghi Bidsorkhi^1,2, Alessio Tamburrano^1,2

, Giovanni De Bellis^1,2, Fabrizio Marra^1,2, Agnese Bregnocchi^1,2

and Maria Sabrina Sarto^1,2

¹ Department of Astronautical, Electrical and Energy Engineering, Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy

² Research Center on Nanotechnology Applied to Engineering of Sapienza (CNIS), Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy

Polymers 2018, 10(1), 82; https://doi.org/10.3390/polym10010082 - 16 Jan 2018

Cited by 13 | Viewed by 5637

Abstract

Recently, graphene-polymer composites gained a central role in advanced stress and strain sensing. A fundamental step in the production of epoxy-composites filled with graphene nanoplatelets (GNPs) consists in the exfoliation and dispersion of expanded graphite in a proper solvent, in the mixing of [...] Read more.

Recently, graphene-polymer composites gained a central role in advanced stress and strain sensing. A fundamental step in the production of epoxy-composites filled with graphene nanoplatelets (GNPs) consists in the exfoliation and dispersion of expanded graphite in a proper solvent, in the mixing of the resulting GNP suspension with the polymer matrix, and in the final removal of the solvent from the composite before curing through evaporation. The effects of traces of residual solvent on polymer curing process are usually overlooked, even if it has been found that even a small amount of residual solvent can affect the mechanical properties of the final composite. In this paper, we show that residual traces of N,N′-Dimethylformamide (DMF) in vinylester epoxy composites can induce relevant variations of the electrical, mechanical and electromechanical properties of the cured GNP-composite. To this purpose, a complete analysis of the morphological and structural characteristics of the composite samples produced using different solvent mixtures (combining acetone and DMF) is performed. Moreover, electrical, mechanical and electromechanical properties of the produced composites are assessed. In particular, the effect on the piezoresistive response of the use of DMF in the solvent mixture is analyzed using an experimental strain dependent percolation law to fit the measured electromechanical data. It is shown that the composites realized using a higher amount of DMF are characterized by a higher electrical conductivity and by a strong reduction of Young’s Modulus. Full article

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15 pages, 4258 KiB

Open AccessArticle

Enhanced Oxidation Resistance of Polyphenylene Sulfide Composites Based on Montmorillonite Modified by Benzimidazolium Salt

by Jian Xing^1,*

, Zhenzhen Xu¹ and Bingyao Deng²

¹ School of Textile and Garment, Anhui Polytechnic University, Wuhu 241000, China

² Key Laboratory of Science &Technology of Eco-Textile, Ministry of Education, Jiangnan University, Wuxi 214122, China

Polymers 2018, 10(1), 83; https://doi.org/10.3390/polym10010083 - 17 Jan 2018

Cited by 53 | Viewed by 7320

Abstract

Organic montmorillonite (MMT) modified by 1,3-dihexadecyl-3H-benzimidazolium bromide (Bz) was used to prepare polyphenylene sulfide (PPS)/MMT composites by melting intercalation. The PPS/MMT composites showed mixed morphology, being comprised of exfoliated and intercalated structures with slight agglomerates. The tensile property of PPS/MMT composites [...] Read more.

Organic montmorillonite (MMT) modified by 1,3-dihexadecyl-3H-benzimidazolium bromide (Bz) was used to prepare polyphenylene sulfide (PPS)/MMT composites by melting intercalation. The PPS/MMT composites showed mixed morphology, being comprised of exfoliated and intercalated structures with slight agglomerates. The tensile property of PPS/MMT composites was significantly improved due to the good dispersion of the MMT nanolayers. The test results showed that the tensile strength retention of PPS/MMT composites was higher than that of pure PPS after the oxidation treatment. Moreover, FTIR and XPS analyses were also used to evaluate the oxidation resistance of PPS composites. The FTIR analysis confirmed that adding MMT could better limit the damage of the C–S group and retard the generation of sulfuryl groups (–SO₂–) during the oxidation treatment compared to pure PPS. The XPS analysis also suggested that the addition of MMT could reduce the chemical combination of the elements sulfur (S) and oxygen (O) during oxidation treatment. Furthermore, the MMT nanolayers could also promote the transfer of S from a C–S bond into an –SO₂– group. Full article

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

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10 pages, 2201 KiB

Open AccessArticle

Quartz Microcrystal-Hybridized Organosilicone Encapsulant with Enhanced Optical and Thermal Performances

by Xin Chen^1,2,†, Yancong Feng^1,2,†, Xiao Wang^1,2, En Li^1,2, Yao Wang^1,2

, Lingling Shui^1,2, Hao Li^1,2,*

, Nan Li^3,4 and Guofu Zhou^1,2,3,4,*

¹ Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China

² National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou 510006, China

³ Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, China

⁴ Academy of Shenzhen Guohua Optoelectronics, Shenzhen 518110, China

^† These authors contributed equally to this work.

Polymers 2018, 10(1), 84; https://doi.org/10.3390/polym10010084 - 16 Jan 2018

Cited by 3 | Viewed by 4593

Abstract

Encapsulant is one determining factor underpinning the device lifetimes of organic optoelectronics. However, encapsulant seriously needs improvement in optical, thermal, and mechanical properties, especially to develop organic light emitting diodes. In this study, we prepared an in situ crosslinked organosilane composite containing benzyloxy [...] Read more.

Encapsulant is one determining factor underpinning the device lifetimes of organic optoelectronics. However, encapsulant seriously needs improvement in optical, thermal, and mechanical properties, especially to develop organic light emitting diodes. In this study, we prepared an in situ crosslinked organosilane composite containing benzyloxy and glycidyl-modified quartz microcrystal (mQMC) as high performance encapsulant. In the present work, methylphenylsilanediol (MPSD) was introduced as a novel crosslinker to impart appropriate structural strength. Along with increasing mQMC fillers, this organosilane system shows improved properties, such as refractive index, thermal stability, and storage modulus. Specifically, these hybridized mQMCs in the organosilane framework may facilitate an approximate two-fold increase (0.238 W/(m·K)) in overall thermal conductivity at the determined concentration. Full article

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

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14 pages, 2479 KiB

Open AccessArticle

Mucoadhesive Interpolyelectrolyte Complexes for the Buccal Delivery of Clobetasol

by Venera R. Garipova¹, Chiara G. M. Gennari², Francesca Selmin², Francesco Cilurzo² and Rouslan I. Moustafine^1,*

¹ Department of Pharmaceutical, Analytical and Toxicological Chemistry, Kazan State Medical University, 49 Butlerov Street, 420012 Kazan, Russia

² Department of Pharmaceutical Science, University of Milan, Via G. Colombo 71, 20133 Milan, Italy

Polymers 2018, 10(1), 85; https://doi.org/10.3390/polym10010085 - 17 Jan 2018

Cited by 31 | Viewed by 5308

Abstract

This work aimed to investigate the feasibility to design: (a) a mucoadhesive interpolyelectrolyte complex (IPEC) loaded with clobetasol propionate (CP) intended to treat oral lichen planus and (b) individuate an orodispersible dosage form suitable for its administration. IPECs were synthesized by mixing Eudragit [...] Read more.

This work aimed to investigate the feasibility to design: (a) a mucoadhesive interpolyelectrolyte complex (IPEC) loaded with clobetasol propionate (CP) intended to treat oral lichen planus and (b) individuate an orodispersible dosage form suitable for its administration. IPECs were synthesized by mixing Eudragit^® E PO (EPO) and different grades of cross-linked polyacrylate derivatives, in different molar ratios, namely 1:1, 1:2, and 2:1. All IPECs resulted at nanoscale independently of their composition (120–200 nm). Both zeta-potentials (ζ) and mucoadhesive performances were influenced by the ratio between polymers. On the bases of the preliminary data, IPECs made of Polycarbophil and EPO in the 1:2 ratio were loaded with CP. The encapsulation efficiency was up 88% independently of the CP-IPEC ratio. The drug encapsulation caused IPEC destabilization in water, as it was noticed by the increase of ζ values and the formation of aggregates. Oral lyophilisates were prepared by freeze-drying slurries made of placebo or CP loaded IPECs, maltodextrin with a dextrose equivalent 38 and Span^®80. The optimized formulation permitted to obtain a fast disintegration upon contact with water reducing the tendency of IPECs to aggregate. Moreover, oral lyophilisates allowed improving the apparent solubility of CP throughout the in vitro release experiment. Full article

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

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18 pages, 3589 KiB

Open AccessArticle

The Effect of Reactive Ionic Liquid or Plasticizer Incorporation on the Physicochemical and Transport Properties of Cellulose Acetate Propionate-Based Membranes

by Edyta Rynkowska^1,2

, Kateryna Fatyeyeva^2,*

, Joanna Kujawa¹

, Krzysztof Dzieszkowski¹, Andrzej Wolan^1,3 and Wojciech Kujawski^1,*

¹ Faculty of Chemistry, Nicolaus Copernicus University in Toruń, 7, Gagarina Street, 87-100 Torun, Poland

² Normandie University, UNIROUEN, INSA Rouen, CNRS, PBS, 76000 Rouen, France

³ Synthex Technologies Sp. z o.o., 7 Gagarina Street, 87-100 Toruń, Poland

Polymers 2018, 10(1), 86; https://doi.org/10.3390/polym10010086 - 17 Jan 2018

Cited by 33 | Viewed by 7372

Abstract

Pervaporation is a membrane-separation technique which uses polymeric and/or ceramic membranes. In the case of pervaporation processes applied to dehydration, the membrane should transport water molecules preferentially. Reactive ionic liquid (RIL) (3-(1,3-diethoxy-1,3-dioxopropan-2-yl)-1-methyl-1H-imidazol-3-ium) was used to prepare novel dense cellulose acetate propionate [...] Read more.

Pervaporation is a membrane-separation technique which uses polymeric and/or ceramic membranes. In the case of pervaporation processes applied to dehydration, the membrane should transport water molecules preferentially. Reactive ionic liquid (RIL) (3-(1,3-diethoxy-1,3-dioxopropan-2-yl)-1-methyl-1H-imidazol-3-ium) was used to prepare novel dense cellulose acetate propionate (CAP) based membranes, applying the phase-inversion method. The designed polymer-ionic liquid system contained ionic liquid partially linked to the polymeric structure via the transesterification reaction. The various physicochemical, mechanical, equilibrium and transport properties of CAP-RIL membranes were determined and compared with the properties of CAP membranes modified with plasticizers, i.e., tributyl citrate (TBC) and acetyl tributyl citrate (ATBC). Thermogravimetric analysis (TGA) testified that CAP-RIL membranes as well as CAP membranes modified with TBC and ATBC are thermally stable up to at least 120 °C. Tensile tests of the membranes revealed improved mechanical properties reflected by reduced brittleness and increased elongation at break achieved for CAP-RIL membranes in contrast to pristine CAP membranes. RIL plasticizes the CAP matrix, and CAP-RIL membranes possess preferable mechanical properties in comparison to membranes with other plasticizers investigated. The incorporation of RIL into CAP membranes tuned the surface properties of the membranes, enhancing their hydrophilic character. Moreover, the addition of RIL into CAP resulted in an excellent improvement of the separation factor, in comparison to pristine CAP membranes, in pervaporation dehydration of propan-2-ol. The separation factor β increased from ca. 10 for pristine CAP membrane to ca. 380 for CAP-16.7-RIL membranes contacting an azeotropic composition of water-propan-2-ol mixture (i.e., 12 wt % water). Full article

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14 pages, 27800 KiB

Open AccessArticle

Mechanical Properties Changes of Irradiated Thermoplastic Elastomer

by David Manas^1,2,†, Ales Mizera^1,*

, Miroslav Manas¹, Martin Ovsik²

, Lenka Hylova², Stanislav Sehnalek¹ and Pavel Stoklasek¹

¹ CEBIA-Tech, Faculty of Applied Informatics, Tomas Bata University in Zlin, Nad Stranemi 4511, 760 05 Zlín, Czech Republic

² Faculty of Technology, Tomas Bata University in Zlin, Vavreckova 275, 760 01 Zlín, Czech Republic

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

Polymers 2018, 10(1), 87; https://doi.org/10.3390/polym10010087 - 17 Jan 2018

Cited by 18 | Viewed by 6683

Abstract

Some polymers need a cross-linking agent for the controlled cross-linking process of polymers with a tendency to degradation during the radiation cross-linking process. While, on the other hand, other polymers do not need a cross-linking agent—predominantly there are cross-linking polymers. The Thermo-Plastic Elastomer [...] Read more.

Some polymers need a cross-linking agent for the controlled cross-linking process of polymers with a tendency to degradation during the radiation cross-linking process. While, on the other hand, other polymers do not need a cross-linking agent—predominantly there are cross-linking polymers. The Thermo-Plastic Elastomer (TPE) that was used belongs to this group of predominantly cross-linking polymers; however, this agent is added because of faster reaction times and smaller irradiation doses. Microindentation–tensile and tensile impact tests were carried out on a thermoplastic sample—with, and without, a cross-linking agent. Small changes were measured between these materials at low radiation doses, (up to 66 kGy); nevertheless, at higher doses, the influence of the cross-linking agent on the mechanical properties is significant. Full article

(This article belongs to the Special Issue Elastomers)

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14 pages, 2316 KiB

Open AccessArticle

One-Pot Synthesis of Waterborne Polymeric Dispersions Stabilized with Alkali-Soluble Resins

by Massimo Bandiera^1,2, Roelof Balk² and Maria J. Barandiaran^1,*

¹ POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country UPV/EHU, 20018 Donostia-San Sebastián, Spain

² BASF SE, 67056 Ludwigshafen am Rhein, Germany

Polymers 2018, 10(1), 88; https://doi.org/10.3390/polym10010088 - 18 Jan 2018

Cited by 18 | Viewed by 6361

Abstract

Alkali-soluble resins (ASRs) are a type of electrosteric emulsifiers of high interest because they can profitably improve the features of waterborne dispersions. In this work, they have been synthesized in-situ through a one-pot approach and they have been used as polymeric surfactants for [...] Read more.

Alkali-soluble resins (ASRs) are a type of electrosteric emulsifiers of high interest because they can profitably improve the features of waterborne dispersions. In this work, they have been synthesized in-situ through a one-pot approach and they have been used as polymeric surfactants for a second emulsion polymerization step in the same reactor. This strategy provides some advantages compared to other polymerization techniques, like the intensification of the process and the absence of organic solvents. Their use can also further reduce the environmental impact of formulations for film-forming applications, since grafting reactions with the particles have been observed and quantified in relation with the synthetic parameters. These chemical linkages with the particles may reduce the leaching and the release of surfactants from polymeric films, for example in water-based coatings or adhesives. The systems have been also studied from the kinetics point of view, finding relevant differences with other electrosterically stabilized processes from the literature, as well as concerns the nucleation mechanism. Full article

(This article belongs to the Special Issue Emulsion Polymerization)

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16 pages, 5122 KiB

Open AccessArticle

Poly(carbonate urethane)-Based Thermogels with Enhanced Drug Release Efficacy for Chemotherapeutic Applications

by Benjamin Qi Yu Chan^1,2,†

, Hongwei Cheng^3,†, Sing Shy Liow¹, Qingqing Dou¹, Yun-Long Wu^3,*

, Xian Jun Loh^1,2,4,* and Zibiao Li^1,*

¹ Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, Singapore 138634, Singapore

² Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore

³ Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen 361102, China

⁴ Singapore Eye Research Institute, 11 Third Hospital Avenue, Singapore 168751, Singapore

^† These authors have made equal contributions to this work.

Polymers 2018, 10(1), 89; https://doi.org/10.3390/polym10010089 - 18 Jan 2018

Cited by 37 | Viewed by 6504

Abstract

In this study, we report the synthesis and characterisation of a thermogelling poly(carbonate urethane) system comprising poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(polytetrahydrofuran carbonate) (PTHF carbonate). The incorporation of PTHF carbonate allowed for the control of the lower critical solution temperature (LCST) [...] Read more.

In this study, we report the synthesis and characterisation of a thermogelling poly(carbonate urethane) system comprising poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(polytetrahydrofuran carbonate) (PTHF carbonate). The incorporation of PTHF carbonate allowed for the control of the lower critical solution temperature (LCST) and decreased critical gelation concentration (CGC) of the thermogels significantly. In addition, the as-prepared thermogels displayed low toxicity against HepG2, L02 and HEK293T cells. Drug release studies were carried out using doxorubicin (Dox). Studies conducted using nude mice models with hepatocellular carcinoma revealed that the Dox-loaded poly(PEG/PPG/PTHF carbonate urethane) thermogels showed excellent in vivo anti-tumour performance and effectively inhibited tumour growth in the tested model. Full article

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

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13 pages, 3363 KiB

Open AccessArticle

Effect of Hydroxyl Monomers on the Enzymatic Degradation of Poly(ethylene succinate), Poly(butylene succinate), and Poly(hexylene succinate)

by Zhenhui Bai^1,†, Yun Liu^2,†, Tingting Su^1,* and Zhanyong Wang^1,*

¹ College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning Shihua University, Fushun 113001, China

² College of Life S ciences and Oceanography, Shenzhen University, Shenzhen 518060, China

^† These authors contributed equally to this work.

Polymers 2018, 10(1), 90; https://doi.org/10.3390/polym10010090 - 18 Jan 2018

Cited by 60 | Viewed by 6892

Abstract

Poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), and poly(hexylene succinate) (PHS), were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied [...] Read more.

Poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), and poly(hexylene succinate) (PHS), were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied heavily on the distance between ester groups, crystallinity, and the hydrophilicity-hydrophobicity balance of polyester surfaces. The weight loss through degradation of the three kinds of polyesters with different hydroxyl monomers took place in the order PHS > PBS > PES. The degradation behavior of the polyesters before and after degradation was analyzed by scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The decrease in relative intensity at 1800–1650 estedpolyesters were degraded simultaneously. The frequencies of the crystalline and amorphous bands were almost identical before and after degradation. Thus, enzymatic degradation did not change the crystalline structure but destroyed it, and the degree of crystallinity markedly decreased. The molecular weight and polydispersity index only changed slightly. The thermal stability of the three kinds of polyesters decreased during enzymatic degradation. Full article

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

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12 pages, 3370 KiB

Open AccessArticle

Thermo-Responsive Starch-g-(PAM-co-PNIPAM): Controlled Synthesis and Effect of Molecular Components on Solution Rheology

by Yifei Fan, Nadia Boulif and Francesco Picchioni^*

Engineering and Technology Institute Groningen, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands

Polymers 2018, 10(1), 92; https://doi.org/10.3390/polym10010092 - 19 Jan 2018

Cited by 31 | Viewed by 8859

Abstract

A series of highly branched random copolymers of acrylamide (AM) and N-isopropylacrylamide (NIPAM) have been prepared from a waxy potato starch-based macroinitiator by aqueous Cu⁰-mediated living radical polymerization (Cu⁰-mediated LRP). The NIPAM intake in the copolymer was varied [...] Read more.

A series of highly branched random copolymers of acrylamide (AM) and N-isopropylacrylamide (NIPAM) have been prepared from a waxy potato starch-based macroinitiator by aqueous Cu⁰-mediated living radical polymerization (Cu⁰-mediated LRP). The NIPAM intake in the copolymer was varied between 0% and 50 mol % to evaluate the influence of chain composition on the aqueous rheological properties as well as their low critical solution temperature (LCST). The viscosity of the copolymer was found to increase with the NIPAM intake and an LCST can be observed when the NIPAM content is high enough (e.g., 50 mol %). In addition, thermo-thickening behavior was observed at a low shear rate (γ ≤ 10 s⁻¹) and higher NIPAM content was found to shift the onset of thermo-thickening behavior to a lower temperature. However, the absolute increase in viscosity values is reduced with the NIPAM intake. Besides this, an interesting significant thermo-thickening behavior was also observed on highly branched starch-g-polyacrylamide at high temperatures (>80 °C), which has not been previously reported. Rheology tests also revealed a good salt-resistant property in copolymers with low NIPAM content (e.g., <25 mol %). Considering the viscosity profile in saline as compared to that in pure water, this NIPAM intake seems to represent an optimum balance of viscosity and salt-resistance performance. Full article

(This article belongs to the Collection Polysaccharides)

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11 pages, 1714 KiB

Open AccessFeature PaperArticle

Aggregation of Cationic Amphiphilic Block and Random Copoly(vinyl ether)s with Antimicrobial Activity

by Yukari Oda^1,2,*

, Kazuma Yasuhara³, Shokyoku Kanaoka^1,4, Takahiro Sato¹

, Sadahito Aoshima^1,*

and Kenichi Kuroda^5,*

¹ Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan

² Current, Department of Applied Chemistry, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395, Japan

³ Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan

⁴ Current, Department of Materials Science, The University of Shiga Prefecture, Hikone, Shiga 522-8533, Japan

⁵ Department of Biologic and Materials Science, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA

Polymers 2018, 10(1), 93; https://doi.org/10.3390/polym10010093 - 19 Jan 2018

Cited by 16 | Viewed by 6227

Abstract

In this study, we investigated the aggregation behaviors of amphiphilic poly(vinyl ether)s with antimicrobial activity. We synthesized a di-block poly(vinyl ether), B38₂₆, composed of cationic primary amine and hydrophobic isobutyl (iBu) side chains, which previously showed antimicrobial activity against [...] Read more.

In this study, we investigated the aggregation behaviors of amphiphilic poly(vinyl ether)s with antimicrobial activity. We synthesized a di-block poly(vinyl ether), B38₂₆, composed of cationic primary amine and hydrophobic isobutyl (iBu) side chains, which previously showed antimicrobial activity against Escherichia coli. B38₂₆ showed similar uptake behaviors as those for a hydrophobic fluorescent dye, 1,6-diphenyl-1,3,5-hexatriene, to counterpart polymers including homopolymer H44 and random copolymer R40₂₅, indicating that the iBu block does not form strong hydrophobic domains. The cryo-TEM observations also indicated that the polymer aggregate of B38₂₆ appears to have low-density polymer chains without any defined microscopic structures. We speculate that B38₂₆ formed large aggregates by liquid-liquid separation due to the weak association of polymer chains. The fluorescence microscopy images showed that B38₂₆ bonds to E. coli cell surfaces, and these bacterial cells were stained by propidium iodide, indicating that the cell membranes were significantly damaged. The results suggest that block copolymers may provide a new platform to design and develop antimicrobial materials that can utilize assembled structures and properties. Full article

(This article belongs to the Special Issue Polymer Micelles)

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10 pages, 2493 KiB

Open AccessArticle

Temperature Scanning Stress Relaxation of an Autonomous Self-Healing Elastomer Containing Non-Covalent Reversible Network Junctions

by Amit Das^1,2

, Aladdin Sallat^1,3

, Frank Böhme¹, Essi Sarlin²

, Jyrki Vuorinen²

, Norbert Vennemann⁴, Gert Heinrich^1,5 and Klaus Werner Stöckelhuber^1,*

¹ Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany

² Laboratory of Materials Science, Tampere University of Technology, P.O. Box 589, 33101 Tampere, Finland

³ Faculty of Chemistry and Food Chemistry, Department of macromolecular Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany

⁴ Faculty of Engineering and Computer Science, University of Applied Sciences Osnabrück, 49076 Osnabrück, Germany

⁵ Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik, Technische Universität Dresden, D-01062 Dresden, Germany

Polymers 2018, 10(1), 94; https://doi.org/10.3390/polym10010094 - 19 Jan 2018

Cited by 35 | Viewed by 8599

Abstract

In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing [...] Read more.

In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering. Full article

(This article belongs to the Special Issue Elastomers)

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18 pages, 2687 KiB

Open AccessArticle

Toughening of Poly(lactic acid) and Thermoplastic Cassava Starch Reactive Blends Using Graphene Nanoplatelets

by Anibal Bher^1,2,3

, Ilke Uysal Unalan^1,4

, Rafael Auras^1,*

, Maria Rubino¹ and Carlos E. Schvezov³

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

² Instituto Sabato, UNSAM-CNEA, San Martin, Buenos Aires 1650, Argentina

³ Instituto de Materiales de Misiones (IMAM), CONICET-UNaM, Posadas, Misiones 3300, Argentina

⁴ Department of Food Engineering, Faculty of Engineering, İzmir University of Economics, İzmir 35330, Turkey

Polymers 2018, 10(1), 95; https://doi.org/10.3390/polym10010095 - 19 Jan 2018

Cited by 48 | Viewed by 7478

Abstract

Poly(lactic acid) (PLA) was reactively blended with thermoplastic cassava starch (TPCS) and functionalized with commercial graphene (GRH) nanoplatelets in a twin-screw extruder, and films were produced by cast-film extrusion. Reactive compatibilization between PLA and TPCS phases was reached by introducing maleic anhydride and [...] Read more.

Poly(lactic acid) (PLA) was reactively blended with thermoplastic cassava starch (TPCS) and functionalized with commercial graphene (GRH) nanoplatelets in a twin-screw extruder, and films were produced by cast-film extrusion. Reactive compatibilization between PLA and TPCS phases was reached by introducing maleic anhydride and a peroxide radical during the reactive blending extrusion process. Films with improved elongation at break and toughness for neat PLA and PLA-g-TPCS reactive blends were obtained by an addition of GRH nanoplatelets. Toughness of the PLA-g-TPCS-GRH was improved by ~900% and ~500% when compared to neat PLA and PLA-g-TPCS, respectively. Crack bridging was established as the primary mechanism responsible for the improvement in the mechanical properties of PLA and PLA-g-TPCS in the presence of the nanofiller due to the high aspect ratio of GRH. Scanning electron microscopy images showed a non-uniform distribution of GRH nanoplatelets in the matrix. Transmittance of the reactive blend films decreased due to the TPCS phase. Values obtained for the reactive blends showed ~20% transmittance. PLA-GRH and PLA-g-TPCS-GRH showed a reduction of the oxygen permeability coefficient with respect to PLA of around 35% and 50%, respectively. Thermal properties, molecular structure, surface roughness, XRD pattern, electrical resistivity, and color of the films were also evaluated. Biobased and compostable reactive blend films of PLA-g-TPCS compounded with GRH nanoplatelets could be suitable for food packaging and agricultural applications. Full article

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

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19 pages, 1968 KiB

Open AccessArticle

Novel Antibacterial Polyglycidols: Relationship between Structure and Properties

by Fabian Marquardt, Cornelia Stöcker, Rita Gartzen, Elisabeth Heine, Helmut Keul^* and Martin Möller^*

Institute of Technical and Macromolecular Chemistry, RWTH Aachen University and DWI Leibniz-Institute for Interactive Materials, Forckenbeckstr. 50, D-52056 Aachen, Germany

Polymers 2018, 10(1), 96; https://doi.org/10.3390/polym10010096 - 20 Jan 2018

Cited by 8 | Viewed by 6119

Abstract

Antimicrobial polymers are an attractive alternative to low molecular weight biocides, because they are non-volatile, chemically stable, and can be used as non-releasing additives. Polymers with pendant quaternary ammonium groups and hydrophobic chains exhibit antimicrobial properties due to the electrostatic interaction between polymer [...] Read more.

Antimicrobial polymers are an attractive alternative to low molecular weight biocides, because they are non-volatile, chemically stable, and can be used as non-releasing additives. Polymers with pendant quaternary ammonium groups and hydrophobic chains exhibit antimicrobial properties due to the electrostatic interaction between polymer and cell wall, and the membrane disruptive capabilities of the hydrophobic moiety. Herein, the synthesis of cationic–hydrophobic polyglycidols with varying structures by post-polymerization modification is presented. The antimicrobial properties of the prepared polyglycidols against E. coli and S. aureus are examined. Polyglycidol with statistically distributed cationic and hydrophobic groups (cationic–hydrophobic balance of 1:1) is compared to (i) polyglycidol with a hydrophilic modification at the cationic functionality; (ii) polyglycidol with both—cationic and hydrophobic groups—at every repeating unit; and (iii) polyglycidol with a cationic–hydrophobic balance of 1:2. A relationship between structure and properties is presented. Full article

(This article belongs to the Special Issue Antimicrobial Polymers)

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11 pages, 3767 KiB

Open AccessArticle

Synthesis of Molecularly Imprinted Cryogels to Deplete Abundant Proteins from Bovine Serum

by Chun Yang^*

, Yan Zhang, Wei-Qin Cao, Xiao-Feng Ji, Jian Wang, Ya-Nan Yan, Tao-Lin Zhong and Yu Wang

School of Chemistry & Chemical Engineering, Yangzhou University, 180 Siwangting RD, Yangzhou 225002, China

Polymers 2018, 10(1), 97; https://doi.org/10.3390/polym10010097 - 20 Jan 2018

Cited by 14 | Viewed by 4783

Abstract

Molecularly imprinted polyacrylamide cryogels were synthesized with pending templates (bovine serums of different concentrations). As the serum concentrations increased in the monomer solutions, the resulting cryogels could adsorb and deplete more proteins from serum samples. Due to the addition of vinyltriethoxysilane (VTEOS) in [...] Read more.

Molecularly imprinted polyacrylamide cryogels were synthesized with pending templates (bovine serums of different concentrations). As the serum concentrations increased in the monomer solutions, the resulting cryogels could adsorb and deplete more proteins from serum samples. Due to the addition of vinyltriethoxysilane (VTEOS) in the prepolymerizing solutions, the polymers came as organic–inorganic hybrid materials. It endued the silica-modified amphoteric polyacrylamide cryogels with improved mechanical strengths. Scanning electron micrography (SEM), Infrared (IR) spectrometry, thermogravimetry-differential thermal analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS) were carried out to characterize these macroporous polymers. Amphoteric cryogels proved to be favorable materials recognizing and binding proteins. When used as liquid chromatography stationary phases, they were capable of simultaneously adsorbing various serum proteins. Electrophoresis showed that abundant proteins were gradually depleted by the cryogels prepared from increased ratios of bovine serums in the monomer solutions. As abundant proteins are always imprinted first, this sample per se imprinting method provides an effective and convenient way to deplete abundant proteins from complex samples such as serums, meanwhile concentrating and collecting scarce species therein. Full article

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

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19 pages, 16132 KiB

Open AccessArticle

Flexural Behaviour of Carbon Textile-Reinforced Concrete with Prestress and Steel Fibres

by Yunxing Du^1,2,*, Xinying Zhang², Lingling Liu², Fen Zhou^1,2, Deju Zhu^1,2 and Wei Pan³

¹ Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province, Changsha 410082, China

² College of Civil Engineering, Hunan University, Changsha 410082, China

³ Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China

Polymers 2018, 10(1), 98; https://doi.org/10.3390/polym10010098 - 20 Jan 2018

Cited by 44 | Viewed by 6704

Abstract

Four-point bending tests were adopted to investigate the influences of the number of textile layers, volume content of steel fibres, and prestress on the flexural behaviour of carbon textile-reinforced concrete (TRC). The failure mode of the specimen changed from debonding failure to shear [...] Read more.

Four-point bending tests were adopted to investigate the influences of the number of textile layers, volume content of steel fibres, and prestress on the flexural behaviour of carbon textile-reinforced concrete (TRC). The failure mode of the specimen changed from debonding failure to shear failure, accompanied by the matrix-textile interfacial debonding with an increasing number of textile layers. The interfacial bonding performance between the textile and matrix improved with the addition of steel fibres in the TRC specimens. The presence of prestress or steel fibres improved first-crack and ultimate stresses of the TRC specimen. In comparison with the first-crack stress, a more pronounced enhancement in the ultimate stress was achieved by the addition of steel fibres. However, the effect of prestress on the first-crack stress was found to be more significant than on the ultimate stress. The prestress combined with steel fibres further improved the flexural behaviour of the TRC specimens. The prestressed TRC specimens with 1% volume content of steel fibres effectively avoided debonding. Thus, the utilization of the textiles could be improved. Full article

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

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13 pages, 1960 KiB

Open AccessArticle

Temperature-Responsive Polymer Microgel-Gold Nanorods Composite Particles: Physicochemical Characterization and Cytocompatibility

by Aslam Khan^1,*

, Tajdar Husain Khan², Maqusood Ahamed¹

, Ahmed Mohamed El-Toni^1,3, Ali Aldalbahi^1,4

, Javed Alam¹

and Tansir Ahamad⁴

¹ King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia

² College of Pharmacy, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia

³ Central Metallurgical Research and Development Institute, CMRDI, Helwan 11421, Egypt

⁴ Department of Chemistry, King Saud University, Riyadh 11451, Saudi Arabia

Polymers 2018, 10(1), 99; https://doi.org/10.3390/polym10010099 - 20 Jan 2018

Cited by 14 | Viewed by 7314

Abstract

In this paper, we report an easy route for preparing new metal nanorod-polymer composites consisting of gold nanorods, Au NRs, and temperature responsive copolymer “microgel” particles. The microgel particles of ~200 nm in size, which contain carboxylic acid groups, were prepared by surfactant-free [...] Read more.

In this paper, we report an easy route for preparing new metal nanorod-polymer composites consisting of gold nanorods, Au NRs, and temperature responsive copolymer “microgel” particles. The microgel particles of ~200 nm in size, which contain carboxylic acid groups, were prepared by surfactant-free emulsion polymerization of a selected mixture made of N-isopropylacylamide and acrylic acid in the presence of a cross-linker N,N′-methylenebisacrylamide. The electrostatic interactions between the cationic cetyltrimethylammonium bromide (CTAB) stabilized Au NRs and anionic microgel particles were expected to occur in order to prepare stable Au NRs-microgel composite particles. The optical and structural characterization of the composite was achieved using UV-Vis spectroscopy, Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and dynamic light scattering (DLS). TEM image shows that Au NRs are attached on the surface of the microgel particles. Dynamic light scattering measurements prove that the composite particles are temperature responsive, which means the particles undergo a decrease in size as the temperature increases above its phase transition temperature. In vitro cytotoxicity of the composite materials were tested by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Lactate dehydrogenase (LDH), and hemolysis assay, which showed non-toxicity (biocompatibility). Full article

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

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8 pages, 2583 KiB

Open AccessCommunication

Photoluminescence Enhancement of Poly(3-methylthiophene) Nanowires upon Length Variable DNA Hybridization

by Jingyuan Huang¹, Jinho Choi², Gil Sun Lee³, Fengchun Chen¹, Chunzhi Cui^1,*

, Long Yi Jin^1,* and Dong Hyuk Park^2,*

¹ Department of Chemistry, College of Science, and Key Laboratory for Organism Resources of the Changbai Mountain and Functional Molecules, Ministry of Education, Yanbian University, Yanji 133002, China

² Department of Applied Organic Materials Engineering, Inha University, Incheon 402-751, Korea

³ Department of General Education, Kookmin University, Seoul 02707, Korea

Polymers 2018, 10(1), 100; https://doi.org/10.3390/polym10010100 - 20 Jan 2018

Cited by 5 | Viewed by 5265

Abstract

The use of low-dimensional inorganic or organic nanomaterials has advantages for DNA and protein recognition due to their sensitivity, accuracy, and physical size matching. In this research, poly(3-methylthiophene) (P3MT) nanowires (NWs) are electrochemically prepared with dopant followed by functionalization with probe DNA (pDNA) [...] Read more.

The use of low-dimensional inorganic or organic nanomaterials has advantages for DNA and protein recognition due to their sensitivity, accuracy, and physical size matching. In this research, poly(3-methylthiophene) (P3MT) nanowires (NWs) are electrochemically prepared with dopant followed by functionalization with probe DNA (pDNA) sequence through electrostatic interaction. Various lengths of pDNA sequences (10-, 20- and 30-mer) are conjugated to the P3MT NWs respectively followed with hybridization with their complementary target DNA (tDNA) sequences. The nanoscale photoluminescence (PL) properties of the P3MT NWs are studied throughout the whole process at solid state. In addition, the correlation between the PL enhancement and the double helix DNA with various lengths is demonstrated. Full article

(This article belongs to the Special Issue Polymer Based Bio-Sensors)

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16 pages, 4061 KiB

Open AccessArticle

A Combined Self-Consistent Method to Estimate the Effective Properties of Polypropylene/Calcium Carbonate Composites

by Zhongqiang Xiong¹, Shaorong Lu^1,*, Junkun Liu¹, Guangsheng Lv¹, Yuqi Li^1,* and Jinhong Yu^1,2,*

¹ Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China

² Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201, China

Polymers 2018, 10(1), 101; https://doi.org/10.3390/polym10010101 - 21 Jan 2018

Cited by 7 | Viewed by 4614

Abstract

In this work, trying to avoid difficulty of application due to the irregular filler shapes in experiments, self-consistent and differential self-consistent methods were combined to obtain a decoupled equation. The combined method suggests a tenor γ independent of filler-contents being an important connection [...] Read more.

In this work, trying to avoid difficulty of application due to the irregular filler shapes in experiments, self-consistent and differential self-consistent methods were combined to obtain a decoupled equation. The combined method suggests a tenor γ independent of filler-contents being an important connection between high and low filler-contents. On one hand, the constant parameter can be calculated by Eshelby’s inclusion theory or the Mori–Tanaka method to predict effective properties of composites coinciding with its hypothesis. On the other hand, the parameter can be calculated with several experimental results to estimate the effective properties of prepared composites of other different contents. In addition, an evaluation index

σ_{f}^{'}

of the interactional strength between matrix and fillers is proposed based on experiments. In experiments, a hyper-dispersant was synthesized to prepare polypropylene/calcium carbonate (PP/CaCO₃) composites up to 70 wt % of filler-content with dispersion, whose dosage was only 5 wt % of the CaCO₃ contents. Based on several verifications, it is hoped that the combined self-consistent method is valid for other two-phase composites in experiments with the same application progress as in this work. Full article

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17 pages, 3663 KiB

Open AccessArticle

Highly Zeolite-Loaded Polyvinyl Alcohol Composite Membranes for Alkaline Fuel-Cell Electrolytes

by Po-Ya Hsu¹, Ting-Yu Hu¹, Selvaraj Rajesh Kumar¹

, Chia-Hao Chang², Kevin C.-W. Wu², Kuo-Lun Tung² and Shingjiang Jessie Lue^1,3,4,*

¹ Department of Chemical and Materials Engineering, and Green Technology Research Center, Chang Gung University, Guishan District, Taoyuan City 333, Taiwan

² Department of Chemical Engineering, National Taiwan University, Da-an, Taipei City 106, Taiwan

³ Department of Radiation Oncology, Chang Gung Memorial Hospital, Guishan District, Taoyuan City 333, Taiwan

⁴ Department of Safety, Health and Environmental Engineering, Ming-Chi University of Technology, Taishan District, New Taipei City 243, Taiwan

Polymers 2018, 10(1), 102; https://doi.org/10.3390/polym10010102 - 22 Jan 2018

Cited by 43 | Viewed by 9497

Abstract

Having a secure and stable energy supply is a top priority for the global community. Fuel-cell technology is recognized as a promising electrical energy generation system for the twenty-first century. Polyvinyl alcohol/zeolitic imidazolate framework-8 (PVA/ZIF-8) composite membranes were successfully prepared in this work [...] Read more.

Having a secure and stable energy supply is a top priority for the global community. Fuel-cell technology is recognized as a promising electrical energy generation system for the twenty-first century. Polyvinyl alcohol/zeolitic imidazolate framework-8 (PVA/ZIF-8) composite membranes were successfully prepared in this work from direct ZIF-8 suspension solution (0–45.4 wt %) and PVA mixing to prevent filler aggregation for direct methanol alkaline fuel cells (DMAFCs). The ZIF-8 fillers were chosen for the appropriate cavity size as a screening aid to allow water and suppress methanol transport. Increased ionic conductivities and suppressed methanol permeabilities were achieved for the PVA/40.5% ZIF-8 composites, compared to other samples. A high power density of 173.2 mW cm⁻² was achieved using a KOH-doped PVA/40.5% ZIF-8 membrane in a DMAFC at 60 °C with 1–2 mg cm⁻² catalyst loads. As the filler content was raised beyond 45.4 wt %, adverse effects resulted and the DMAFC performance (144.9 mW cm⁻²) was not improved further. Therefore, the optimal ZIF-8 content was approximately 40.5 wt % in the polymeric matrix. The specific power output was higher (58 mW mg⁻¹) than most membranes reported in the literature (3–18 mW mg⁻¹). Full article

(This article belongs to the Special Issue Polymeric Membranes)

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16 pages, 3462 KiB

Open AccessArticle

Designing High-Refractive Index Polymers Using Materials Informatics

by Vishwesh Venkatraman^*

and Bjørn Kåre Alsberg^*

Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway

Polymers 2018, 10(1), 103; https://doi.org/10.3390/polym10010103 - 22 Jan 2018

Cited by 34 | Viewed by 12651

Abstract

A machine learning strategy is presented for the rapid discovery of new polymeric materials satisfying multiple desirable properties. Of particular interest is the design of high refractive index polymers. Our in silico approach employs a series of quantitative structure–property relationship models that facilitate [...] Read more.

A machine learning strategy is presented for the rapid discovery of new polymeric materials satisfying multiple desirable properties. Of particular interest is the design of high refractive index polymers. Our in silico approach employs a series of quantitative structure–property relationship models that facilitate rapid virtual screening of polymers based on relevant properties such as the refractive index, glass transition and thermal decomposition temperatures, and solubility in standard solvents. Exploration of the chemical space is carried out using an evolutionary algorithm that assembles synthetically tractable monomers from a database of existing fragments. Selected monomer structures that were further evaluated using density functional theory calculations agree well with model predictions. Full article

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8 pages, 3032 KiB

Open AccessCommunication

Magnetically Tunable Vibration Transmissibility for Polyurethane Magnetic Elastomers

by Hiroyuki Endo^1,2, Shunsuke Kato^1,2, Mayuko Watanebe³, Takehito Kikuchi⁴, Mika Kawai^1,2 and Tetsu Mitsumata^1,2,3,*

¹ Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan

² ALCA, Japan Science and Technology Agency, Tokyo 102-0076, Japan

³ Faculty of Engineering, Niigata University, Niigata 950-2181, Japan

⁴ Faculty of Science and Technology, Oita University, Oita 870-1192, Japan

Polymers 2018, 10(1), 104; https://doi.org/10.3390/polym10010104 - 22 Jan 2018

Cited by 11 | Viewed by 6715

Abstract

The effect of a weak magnetic field on vibration transmissibility was investigated for magnetic elastomers with various volume fractions of magnetic particles. Polyurethane elastomers without magnetic particles exhibited a natural frequency at 53 Hz and were insensitive to a magnetic field of 60 [...] Read more.

The effect of a weak magnetic field on vibration transmissibility was investigated for magnetic elastomers with various volume fractions of magnetic particles. Polyurethane elastomers without magnetic particles exhibited a natural frequency at 53 Hz and were insensitive to a magnetic field of 60 mT. The natural frequency for magnetic elastomers with a volume fraction of 0.23 was 115 Hz at 0 mT, and increased to 134 Hz at 60 mT. The vibration transmissibility was independent of the magnetic field. A linear relation between the natural frequency and (G/m)^1/2 was observed (G: storage modulus, m: mass), indicating that the observed vibration is basically described by a simple harmonic oscillation. Full article

(This article belongs to the Special Issue Elastomers)

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17 pages, 4515 KiB

Open AccessArticle

Synergistic Effect of Binary Mixed-Pluronic Systems on Temperature Dependent Self-assembly Process and Drug Solubility

by Chin-Fen Lee¹, Hsueh-Wen Tseng¹, Pratap Bahadur² and Li-Jen Chen^1,*

¹ Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan

² Department of Chemistry, Veer Narmad South Gujarat University, Surat 395007, India

Polymers 2018, 10(1), 105; https://doi.org/10.3390/polym10010105 - 22 Jan 2018

Cited by 25 | Viewed by 6750

Abstract

Mixed Pluronic micelles from very hydrophobic and very hydrophilic copolymers were selected to scrutinize the synergistic effect on the self-assembly process as well as the solubilization capacity of ibuprofen. The tendency of mixing behavior between parent copolymers was systematically examined from two perspectives: [...] Read more.

Mixed Pluronic micelles from very hydrophobic and very hydrophilic copolymers were selected to scrutinize the synergistic effect on the self-assembly process as well as the solubilization capacity of ibuprofen. The tendency of mixing behavior between parent copolymers was systematically examined from two perspectives: different block chain lengths at same hydrophilicity (L92 + F108, +F98, +F88, and +F68), as well as various hydrophobicities at the same PPO moiety (L92 + F88, +F87, and +P84). Temperature-dependent micellization in these binary systems was clearly inspected by the combined use of high sensitivity differential scanning calorimeter (HSDSC) and dynamic light scattering (DLS). Changes in heat capacity and size of aggregates at different temperatures during the whole micellization process were simultaneously observed and examined. While distinction of block chain length between parent copolymers increases, the monodispersity of the binary Pluronic systems decreases. However, parent copolymers with distinct PPO moieties do not affirmatively lead to non-cooperative binding, such as the L92 + P84 system. The addition of ibuprofen promotes micellization as well as stabilizes aggregates in the solution. The partial replacement of the hydrophilic Pluronic by a more hydrophobic Pluronic L92 would increase the total hydrophobicity of mixed Pluronics used in the system to substantially enhance the solubility of ibuprofen. The solubility of ibuprofen in the 0.5 wt % L92 + 0.368 wt % P84 system is as high as 4.29 mg/mL, which is 1.4 times more than that of the 0.868 wt % P84 system and 147 times more than that in pure water at 37 °C. Full article

(This article belongs to the Special Issue Polymer Micelles)

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Review

Jump to: Editorial, Research

30 pages, 6176 KiB

Open AccessReview

Recent Development in ITO-free Flexible Polymer Solar Cells

by Shudi Lu^1,*,†, Yang Sun^2,†, Kuankuan Ren², Kong Liu², Zhijie Wang^2,* and Shengchun Qu^2,*

¹ Department of Physics, Hebei Normal University of Science & Technology, Qinhuangdao 066004, China

² Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

^† These authors contributed equally.

Polymers 2018, 10(1), 5; https://doi.org/10.3390/polym10010005 - 22 Dec 2017

Cited by 60 | Viewed by 14190

Abstract

Polymer solar cells have shown good prospect for development due to their advantages of low-cost, light-weight, solution processable fabrication, and mechanical flexibility. Their compatibility with the industrial roll-to-roll manufacturing process makes it superior to other kind of solar cells. Normally, indium tin oxide [...] Read more.

Polymer solar cells have shown good prospect for development due to their advantages of low-cost, light-weight, solution processable fabrication, and mechanical flexibility. Their compatibility with the industrial roll-to-roll manufacturing process makes it superior to other kind of solar cells. Normally, indium tin oxide (ITO) is adopted as the transparent electrode in polymer solar cells, which combines good conductivity and transparency. However, some intrinsic weaknesses of ITO restrict its large scale applications in the future, including a high fabrication price using high temperature vacuum deposition method, scarcity of indium, brittleness and scaling up of resistance with the increase of area. Some substitutes to ITO have emerged in recent years, which can be used in flexible polymer solar cells. This article provides the review on recent progress using other transparent electrodes, including carbon nanotubes, graphene, metal nanowires and nanogrids, conductive polymer, and some other electrodes. Device stability is also discussed briefly. Full article

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

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21 pages, 2185 KiB

Open AccessReview

Spectroscopic Techniques for the Characterization of Polymer Nanocomposites: A Review

by Liliane Bokobza

196 Boulevard Bineau, 92200 Neuilly-Sur-Seine, France

Polymers 2018, 10(1), 7; https://doi.org/10.3390/polym10010007 - 22 Dec 2017

Cited by 53 | Viewed by 11747

Abstract

Due to the growing interest in nanocomposites, a molecular characterization of these materials is essential for the understanding of their properties and for the development of new materials. Spectroscopic techniques that bring information at a molecular level are unavoidable when characterizing polymers, fillers [...] Read more.

Due to the growing interest in nanocomposites, a molecular characterization of these materials is essential for the understanding of their properties and for the development of new materials. Spectroscopic techniques that bring information at a molecular level are unavoidable when characterizing polymers, fillers and composites. Selected examples of the application of fluorescence, solid-state nuclear magnetic resonance (NMR), infrared and Raman spectroscopies, illustrate the potential of these techniques for the analysis of the filler surface, the evaluation of the state of filler dispersion in the host matrix, the extent of interaction between the polymer and the filler particles or the dynamics of polymer chains at the polymer–filler interface. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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27 pages, 4658 KiB

Open AccessReview

Photo Processing for Biomedical Hydrogels Design and Functionality: A Review

by Hongyi Yao^1,†, Jieqiong Wang^1,† and Shengli Mi^1,2,*

¹ Biomanufacturing Engineering Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China

² Open FIESTA Center, Tsinghua University, Shenzhen 518055, China

^† These authors contributed equally to this work.

Polymers 2018, 10(1), 11; https://doi.org/10.3390/polym10010011 - 22 Dec 2017

Cited by 79 | Viewed by 10698

Abstract

A large number of opportunities for biomedical hydrogel design and functionality through photo-processing have stretched the limits of innovation. As both photochemical understanding and engineering technologies continue to develop, more complicated geometries and spatiotemporal manipulations can be realized through photo-exposure, producing multifunctional hydrogels [...] Read more.

A large number of opportunities for biomedical hydrogel design and functionality through photo-processing have stretched the limits of innovation. As both photochemical understanding and engineering technologies continue to develop, more complicated geometries and spatiotemporal manipulations can be realized through photo-exposure, producing multifunctional hydrogels with specific chemical, biological and physical characteristics for the achievement of biomedical goals. This report describes the role that light has recently played in the synthesis and functionalization of biomedical hydrogels and primarily the design of photoresponsive hydrogels via different chemical reactions (photo crosslinking and photo degradation) and conventional light curing processes (micropatterning, stereolithography and two/multiphoton techniques) as well as typical biomedical applications of the hydrogels (cell culture, differentiation and in vivo vascularization) and their promising future. Full article

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

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14 pages, 1946 KiB

Open AccessReview

Polymer-Based Nanomaterials and Applications for Vaccines and Drugs

by Jinyu Han^1,2,†, Dandan Zhao^2,†

, Dan Li², Xiaohua Wang^2,3, Zheng Jin^1,* and Kai Zhao^2,3,*

¹ Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, College of Chemistry and Material Sciences, Heilongjiang University, Harbin 150080, China

² Key Laboratory of Microbiology, School of Life Science, Heilongjiang University, Harbin 150080, China

³ School of Biological Science and Technology, University of Jinan, Jinan 250022, China

^† These authors contributed equally to this study.

Polymers 2018, 10(1), 31; https://doi.org/10.3390/polym10010031 - 2 Jan 2018

Cited by 294 | Viewed by 27433

Abstract

Nanotechnology plays a significant role in drug development. As carriers, polymeric nanoparticles can deliver vaccine antigens, proteins, and drugs to the desired site of action. Polymeric nanoparticles with lower cytotoxicity can protect the delivered antigens or drugs from degradation under unfavorable conditions via [...] Read more.

Nanotechnology plays a significant role in drug development. As carriers, polymeric nanoparticles can deliver vaccine antigens, proteins, and drugs to the desired site of action. Polymeric nanoparticles with lower cytotoxicity can protect the delivered antigens or drugs from degradation under unfavorable conditions via a mucosal administration route; further, the uptake of nanoparticles by antigen-presenting cells can increase and induce potent immune responses. Additionally, nanomaterials are widely used in vaccine delivery systems because nanomaterials can make the vaccine antigen long-acting. This review focuses on some biodegradable polymer materials such as natural polymeric nanomaterials, chemically synthesized polymer materials, and biosynthesized polymeric materials, and points out the advantages and the direction of research on degradable polymeric materials. The application and future perspectives of polymeric materials as delivery carriers and vaccine adjuvants in the field of drugs and vaccines are presented. With the increase of knowledge and fundamental understandings of polymer-based nanomaterials, means of integrating some other attractive properties, such as slow release, target delivery, and alternative administration methods and delivery pathways are feasible. Polymer-based nanomaterials have great potential for the development of novel vaccines and drug systems for certain needs, including single-dose and needle-free deliveries of vaccine antigens and drugs in the future. Full article

(This article belongs to the Special Issue Hydrophilic Polymers)

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38 pages, 3723 KiB

Open AccessReview

Review of Progress in Shape Memory Epoxies and Their Composites

by József Karger-Kocsis^1,2,*

and Sándor Kéki³

¹ Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary

² MTA–BME Research Group for Composite Science and Technology, Műegyetem rkp. 3, H-1111 Budapest, Hungary

³ Department of Applied Chemistry, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary

Polymers 2018, 10(1), 34; https://doi.org/10.3390/polym10010034 - 29 Dec 2017

Cited by 115 | Viewed by 12181

Abstract

Shape memory polymer (SMP) is capable of memorizing one or more temporary shapes and recovering successively to the permanent shape upon various external stimuli. Beside of the above mentioned one-way variants, also two-way shape memory polymers (SMPs) and shape memory (SM) systems exist [...] Read more.

Shape memory polymer (SMP) is capable of memorizing one or more temporary shapes and recovering successively to the permanent shape upon various external stimuli. Beside of the above mentioned one-way variants, also two-way shape memory polymers (SMPs) and shape memory (SM) systems exist which feature a reversible shape change on the basis of “on-off switching” of the external stimulus. The preparation, properties and modelling of shape memory epoxy resins (SMEP), SMEP foams and composites have been surveyed in this exhaustive review article. The underlying mechanisms and characteristics of SM were introduced. Emphasis was put to show new strategies on how to tailor the network architecture and morphology of EPs to improve their SM performance. To produce SMEPs novel preparation techniques, such as electrospinning, ink printing, solid-state foaming, were tried. The potential of SMEPs and related systems as multifunctional materials has been underlined. Added functionality may include, among others, self-healing, sensing, actuation, porosity control, recycling. Recent developments in the modelling of SMEPs were also highlighted. Based on the recent developments some open topics were deduced which are merit of investigations in future works. Full article

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

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52 pages, 8825 KiB

Open AccessFeature PaperReview

Metal Free Reversible-Deactivation Radical Polymerizations: Advances, Challenges, and Opportunities

by Johannes Kreutzer^1,*

and Yusuf Yagci^1,2,*

¹ Department of Chemistry, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey

² Center of Excellence for Advanced Materials Research (CEAMR) and Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia

Polymers 2018, 10(1), 35; https://doi.org/10.3390/polym10010035 - 29 Dec 2017

Cited by 41 | Viewed by 12825

Abstract

A considerable amount of the worldwide industrial production of synthetic polymers is currently based on radical polymerization methods. The steadily increasing demand on high performance plastics and tailored polymers which serve specialized applications is driven by the development of new techniques to enable [...] Read more.

A considerable amount of the worldwide industrial production of synthetic polymers is currently based on radical polymerization methods. The steadily increasing demand on high performance plastics and tailored polymers which serve specialized applications is driven by the development of new techniques to enable control of polymerization reactions on a molecular level. Contrary to conventional radical polymerization, reversible-deactivation radical polymerization (RDRP) techniques provide the possibility to prepare polymers with well-defined structures and functionalities. The review provides a comprehensive summary over the development of the three most important RDRP methods, which are nitroxide mediated radical polymerization, atom transfer radical polymerization and reversible addition fragmentation chain transfer polymerization. The focus thereby is set on the newest developments in transition metal free systems, which allow using these techniques for biological or biomedical applications. After each section selected examples from materials synthesis and application to biomedical materials are summarized. Full article

(This article belongs to the Special Issue Living Polymerization)

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21 pages, 3205 KiB

Open AccessReview

Integration of Heterogeneous Materials for Wearable Sensors

by Yaser M. Haddara^* and Matiar M. R. Howlader

Electrical & Computer Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada

Polymers 2018, 10(1), 60; https://doi.org/10.3390/polym10010060 - 18 Jan 2018

Cited by 22 | Viewed by 6915

Abstract

Wearable sensors are of interest for several application areas, most importantly for their potential to allow for the design of personal continuous health monitoring systems. For wearable sensors, flexibility is required and imperceptibility is desired. Wearable sensors must be robust to strain, motion, [...] Read more.

Wearable sensors are of interest for several application areas, most importantly for their potential to allow for the design of personal continuous health monitoring systems. For wearable sensors, flexibility is required and imperceptibility is desired. Wearable sensors must be robust to strain, motion, and environmental exposure. A number of different strategies have been utilized to achieve flexibility, imperceptibility, and robustness. All of these approaches require the integration of materials having a range of chemical, mechanical, and thermal properties. We have given a concise review of the range of materials that must be incorporated in wearable sensors regardless of the strategies adopted to achieve wearability. We first describe recent advances in the range of wearable sensing materials and their processing requirements and then discuss the potential routes to the integration of these heterogeneous materials. Full article

(This article belongs to the Special Issue Wearable Sensor)

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28 pages, 15524 KiB

Open AccessReview

Intercalation Polymerization Approach for Preparing Graphene/Polymer Composites

by Yifan Guo¹, Fuxi Peng¹, Huagao Wang¹, Fei Huang¹, Fanbin Meng^1,*, David Hui² and Zuowan Zhou^1,*

¹ Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China

² Department of Mechanical Engineering, University of New Orleans, New Orleans, LA 70148, USA

Polymers 2018, 10(1), 61; https://doi.org/10.3390/polym10010061 - 10 Jan 2018

Cited by 44 | Viewed by 11390

Abstract

The rapid development of society has promoted increasing demand for various polymer materials. A large variety of efforts have been applied in order for graphene strengthened polymer composites to satisfy different requirements. Graphene/polymer composites synthesized by traditional strategies display some striking defects, like [...] Read more.

The rapid development of society has promoted increasing demand for various polymer materials. A large variety of efforts have been applied in order for graphene strengthened polymer composites to satisfy different requirements. Graphene/polymer composites synthesized by traditional strategies display some striking defects, like weak interfacial interaction and agglomeration of graphene, leading to poor improvement in performance. Furthermore, the creation of pre-prepared graphene while being necessary always involves troublesome processes. Among the various preparation strategies, an appealing approach relies on intercalation and polymerization in the interlayer of graphite and has attracted researchers’ attention due to its reliable, fast and simple synthesis. In this review, we introduce an intercalation polymerization strategy to graphene/polymer composites by the intercalation of molecules/ions into graphite interlayers, as well as subsequent polymerization. The key point for regulating intercalation polymerization is tuning the structure of graphite and intercalants for better interaction. Potential applications of the resulting graphene/polymer composites, including electrical conductivity, electromagnetic absorption, mechanical properties and thermal conductivity, are also reviewed. Furthermore, the shortcomings, challenges and prospects of intercalation polymerization are discussed, which will be helpful to researchers working in related fields. Full article

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

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26 pages, 4367 KiB

Open AccessReview

Self-Assembly of Block and Graft Copolymers in Organic Solvents: An Overview of Recent Advances

by Leonard Ionut Atanase^1,2,*

and Gerard Riess³

¹ Faculty of Dental Medicine, “Apollonia” University, 700399 Iasi, Romania

² Research Institute “Academician Ioan Haulica”, 700399 Iasi, Romania

³ University of Haute Alsace, Ecole Nationale Supérieure de Chimie de Mulhouse, Laboratoire de Photochimie et d’Ingénierie Macromoléculaires, 68093 Mulhouse CEDEX, France

Polymers 2018, 10(1), 62; https://doi.org/10.3390/polym10010062 - 11 Jan 2018

Cited by 76 | Viewed by 11631

Abstract

This review is an attempt to update the recent advances in the self-assembly of amphiphilic block and graft copolymers. Their micellization behavior is highlighted for linear AB, ABC triblock terpolymers, and graft structures in non-aqueous selective polar and non-polar solvents, including solvent mixtures [...] Read more.

This review is an attempt to update the recent advances in the self-assembly of amphiphilic block and graft copolymers. Their micellization behavior is highlighted for linear AB, ABC triblock terpolymers, and graft structures in non-aqueous selective polar and non-polar solvents, including solvent mixtures and ionic liquids. The micellar characteristics, such as particle size, aggregation number, and morphology, are examined as a function of the copolymers’ architecture and molecular characteristics. Full article

(This article belongs to the Special Issue Polymer Micelles)

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28 pages, 8031 KiB

Open AccessReview

Synthesis, Characterization, and Applications of Magnetic Nanoparticles Featuring Polyzwitterionic Coatings

by Philip Biehl^1,2, Moritz Von der Lühe^1,2, Silvio Dutz^3,*

and Felix H. Schacher^1,2,*

¹ Institute of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany

² Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany

³ Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693 Ilmenau, Germany

Polymers 2018, 10(1), 91; https://doi.org/10.3390/polym10010091 - 18 Jan 2018

Cited by 178 | Viewed by 15326

Abstract

Throughout the last decades, magnetic nanoparticles (MNP) have gained tremendous interest in different fields of applications like biomedicine (e.g., magnetic resonance imaging (MRI), drug delivery, hyperthermia), but also more technical applications (e.g., catalysis, waste water treatment) have been pursued. Different surfactants and polymers [...] Read more.

Throughout the last decades, magnetic nanoparticles (MNP) have gained tremendous interest in different fields of applications like biomedicine (e.g., magnetic resonance imaging (MRI), drug delivery, hyperthermia), but also more technical applications (e.g., catalysis, waste water treatment) have been pursued. Different surfactants and polymers are extensively used for surface coating of MNP to passivate the surface and avoid or decrease agglomeration, decrease or modulate biomolecule absorption, and in most cases increase dispersion stability. For this purpose, electrostatic or steric repulsion can be exploited and, in that regard, surface charge is the most important (hybrid) particle property. Therefore, polyelectrolytes are of great interest for nanoparticle coating, as they are able to stabilize the particles in dispersion by electrostatic repulsion due to their high charge densities. In this review article, we focus on polyzwitterions as a subclass of polyelectrolytes and their use as coating materials for MNP. In the context of biomedical applications, polyzwitterions are widely used as they exhibit antifouling properties and thus can lead to minimized protein adsorption and also long circulation times. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

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