Polymers

21 pages, 2042 KiB

Open AccessArticle

Efficient Shielding of Polyplexes Using Heterotelechelic Polysarcosines

by Philipp Michael Klein^1,*, Kristina Klinker^2,3, Wei Zhang¹, Sarah Kern¹, Eva Kessel¹, Ernst Wagner^1,4

and Matthias Barz^2,*

¹ Department of Pharmacy, Ludwig-Maximilians-Universität (LMU) Munich, Pharmaceutical Biotechnology, Butenandtstrasse 5-13, D-81377 Munich, Germany

² Institute of Organic Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, D-55128 Mainz, Germany

³ Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany

⁴ Nanosystems Initiative Munich, Schellingstraße 4, D-80799 Munich, Germany

Polymers 2018, 10(6), 689; https://doi.org/10.3390/polym10060689 - 20 Jun 2018

Cited by 22 | Viewed by 7729

Abstract

Shielding agents are commonly used to shield polyelectrolyte complexes, e.g., polyplexes, from agglomeration and precipitation in complex media like blood, and thus enhance their in vivo circulation times. Since up to now primarily poly(ethylene glycol) (PEG) has been investigated to shield non-viral carriers [...] Read more.

Shielding agents are commonly used to shield polyelectrolyte complexes, e.g., polyplexes, from agglomeration and precipitation in complex media like blood, and thus enhance their in vivo circulation times. Since up to now primarily poly(ethylene glycol) (PEG) has been investigated to shield non-viral carriers for systemic delivery, we report on the use of polysarcosine (pSar) as a potential alternative for steric stabilization. A redox-sensitive, cationizable lipo-oligomer structure (containing two cholanic acids attached via a bioreducible disulfide linker to an oligoaminoamide backbone in T-shape configuration) was equipped with azide-functionality by solid phase supported synthesis. After mixing with small interfering RNA (siRNA), lipopolyplexes formed spontaneously and were further surface-functionalized with polysarcosines. Polysarcosine was synthesized by living controlled ring-opening polymerization using an azide-reactive dibenzo-aza-cyclooctyne-amine as an initiator. The shielding ability of the resulting formulations was investigated with biophysical assays and by near-infrared fluorescence bioimaging in mice. The modification of ~100 nm lipopolyplexes was only slightly increased upon functionalization. Cellular uptake into cells was strongly reduced by the pSar shielding. Moreover, polysarcosine-shielded polyplexes showed enhanced blood circulation times in bioimaging studies compared to unshielded polyplexes and similar to PEG-shielded polyplexes. Therefore, polysarcosine is a promising alternative for the shielding of non-viral, lipo-cationic polyplexes. Full article

(This article belongs to the Special Issue Hydrophilic Polymers)

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18 pages, 12522 KiB

Open AccessArticle

Enzymatic Degradation of Poly(butylene succinate) Copolyesters Synthesized with the Use of Candida antarctica Lipase B

by Aleksandra Wcisłek¹, Agueda Sonseca Olalla^1,2, Andrew McClain³, Agnieszka Piegat¹, Peter Sobolewski¹

, Judit Puskas³ and Miroslawa El Fray^1,*

¹ Division of Functional Materials and Biomaterials, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Szczecin, Al. Piastow 45, 71-311 Szczecin, Poland

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

³ Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, USA

Polymers 2018, 10(6), 688; https://doi.org/10.3390/polym10060688 - 20 Jun 2018

Cited by 37 | Viewed by 6794

Abstract

Biodegradable polymers are an active area of investigation, particularly ones that can be produced from sustainable, biobased monomers, such as copolymers of poly(butylene succinate) (PBS). In this study, we examine the enzymatic degradation of poly(butylene succinate-dilinoleic succinate) (PBS-DLS) copolymers obtained by “green” enzymatic [...] Read more.

Biodegradable polymers are an active area of investigation, particularly ones that can be produced from sustainable, biobased monomers, such as copolymers of poly(butylene succinate) (PBS). In this study, we examine the enzymatic degradation of poly(butylene succinate-dilinoleic succinate) (PBS-DLS) copolymers obtained by “green” enzymatic synthesis using lipase B from Candida antarctica (CALB). The copolymers differed in their hard to soft segments ratio, from 70:30 to 50:50 wt %. Enzymatic degradation was carried out on electrospun membranes (scaffolds) and compression-moulded films using lipase from Pseudomomas cepacia. Poly(ε-caprolactone) (PCL) was used as a reference aliphatic polyester. The degradation process was monitored gravimetrically via water uptake and mass loss. After 24 days, approx. 40% mass loss was observed for fibrous materials prepared from the PBS-DLS 70:30 copolymer, as compared to approx. 10% mass loss for PBS-DLS 50:50. Infrared spectroscopy (FTIR) and size exclusion chromatography (SEC) analysis were used to examine changes in chemical structure. Differential scanning calorimetry (DSC) and scanning light microscopy (LSM) revealed changes in degree of crystallinity, and changes in surface morphology, consistent with a surface erosion mechanism. We conclude that the obtained copolymers are suitable for tissue engineering applications thanks to tuneable degradation and lack of acidification during breakdown. Full article

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

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14 pages, 2147 KiB

Open AccessArticle

Modular Synthesis of Bioreducible Gene Vectors through Polyaddition of N,N′-Dimethylcystamine and Diglycidyl Ethers

by Guoying Si^1,†, M. Rachèl Elzes^1,†

, Johan F. J. Engbersen² and Jos M. J. Paulusse^1,3,*

¹ Department of Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology and TechMed Institute for Health and Biomedical Technologies, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

² 20Med Therapeutics, Zuidhorst 251, Drienerlolaan 5, 7522 NB Enschede, The Netherlands

³ Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands

^† These authors contributed equally to this work.

Polymers 2018, 10(6), 687; https://doi.org/10.3390/polym10060687 - 20 Jun 2018

Cited by 7 | Viewed by 4787

Abstract

Bioreducible, cationic linear poly(amino ether)s (PAEs) were designed as promising gene vectors. These polymers were synthesized by the reaction of a disulfide-functional monomer, N,N′-dimethylcystamine (DMC), and several different diglycidyl ethers. The resulting PAEs displayed a substantial buffer capacity (up to [...] Read more.

Bioreducible, cationic linear poly(amino ether)s (PAEs) were designed as promising gene vectors. These polymers were synthesized by the reaction of a disulfide-functional monomer, N,N′-dimethylcystamine (DMC), and several different diglycidyl ethers. The resulting PAEs displayed a substantial buffer capacity (up to 64%) in the endosomal acidification region of pH 7.4–5.1. The PAEs condense plasmid DNA into 80–200 nm sized polyplexes, and have surface charges ranging from +20 to +40 mV. The polyplexes readily release DNA upon exposure to reducing conditions (2.5 mM DTT) due to the cleavage of the disulfide groups that is present in the main chain of the polymers, as was demonstrated by agarose gel electrophoresis. Upon exposing COS-7 cells to polyplexes that were prepared at polymer/DNA w/w ratios below 48, cell viabilities between 80–100% were observed, even under serum-free conditions. These polyplexes show comparable or higher transfection efficiencies (up to 38%) compared to 25 kDa branched polyethylenimine (PEI) polyplexes (12% under serum-free conditions). Moreover, the PAE-based polyplexes yield transfection efficiencies as high as 32% in serum-containing medium, which makes these polymers interesting for gene delivery applications. Full article

(This article belongs to the Special Issue Polymers in Gene Delivery)

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15 pages, 5677 KiB

Open AccessArticle

Modification of PSf/SPSf Blended Porous Support for Improving the Reverse Osmosis Performance of Aromatic Polyamide Thin Film Composite Membranes

by Li-Fen Liu^1,2,*

, Xing-Ling Gu¹, Xin Xie¹, Rui-Han Li¹, Chun-Yang Yu³, Xiao-Xiao Song^1,2,* and Cong-Jie Gao^1,2

¹ Center for Membrane and Water Science and Technology, Ocean College, Zhejiang University of Technology, Hangzhou 310014, China

² Collaborative Innovation Center of Membrane Separation and Water Treatment of Zhejiang Province, Hangzhou 310014, China

³ State Key Laboratory of Metal Matrix Composites, School of Chemistry & Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China

Polymers 2018, 10(6), 686; https://doi.org/10.3390/polym10060686 - 20 Jun 2018

Cited by 24 | Viewed by 7036

Abstract

In this study, modification of polysulfone (PSf)/sulfonated polysulfone (SPSf) blended porous ultrafiltration (UF) support membranes was proposed to improve the reverse osmosis (RO) performance of aromatic polyamide thin film composite (TFC) membranes. The synergistic effects of solvent, polymer concentration, and SPSf doping content [...] Read more.

In this study, modification of polysulfone (PSf)/sulfonated polysulfone (SPSf) blended porous ultrafiltration (UF) support membranes was proposed to improve the reverse osmosis (RO) performance of aromatic polyamide thin film composite (TFC) membranes. The synergistic effects of solvent, polymer concentration, and SPSf doping content in the casting solution were investigated systematically on the properties of both porous supports and RO membranes. SEM and AFM were combined to characterize the physical properties of the membranes, including surface pore natures (porosity, mean pore radius), surface morphology, and section structure. A contact angle meter was used to analyze the membrane surface hydrophilicity. Permeate experiments were carried out to evaluate the separation performances of the membranes. The results showed that the PSf/SPSf blended porous support modified with 6 wt % SPSf in the presence of DMF and 14 wt % PSf had higher porosity, bigger pore diameter, and a rougher and more hydrophilic surface, which was more beneficial for fabrication of a polyamide TFC membrane with favorable reverse osmosis performance. This modified PSf/SPSf support endowed the RO membrane with a more hydrophilic surface, higher water flux (about 1.2 times), as well as a slight increase in salt rejection than the nascent PSf support. In a word, this work provides a new facile method to improve the separation performance of polyamide TFC RO membranes via the modification of conventional PSf porous support with SPSf. Full article

(This article belongs to the Special Issue Aromatic Polymers)

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14 pages, 5763 KiB

Open AccessReview

A Radio-Fluorogenic Polymer-Gel Makes Fixed Fluorescent Images of Complex Radiation Fields

by John M. Warman^*, Matthijs P. De Haas, Leonard H. Luthjens, Antonia G. Denkova and Tiantian Yao

Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands

Polymers 2018, 10(6), 685; https://doi.org/10.3390/polym10060685 - 20 Jun 2018

Cited by 10 | Viewed by 3862

Abstract

We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g., [...] Read more.

We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g., maleimido-pyrene (MPy). The radio-fluorogenic effect depends on copolymerization of the MPy into growing chains of TBA on radiation-induced polymerization. This converts the maleimido residue, which quenches the pyrene fluorescence, into a succinimido moeity (SPy), which does not. The intensity of the fluorescence is proportional to the yield of free-radicals formed and hence to the local dose deposited. Because the SPy moieties are built into the polymer network, the image is fixed. The method of preparing the gel and imaging the radiation-induced fluorescence are presented and discussed. The effect is illustrated with fluorescent images of the energy deposited in the gel by beams of X-rays, electrons, and protons as well as a radioactive isotope. Full article

(This article belongs to the Special Issue Polymer Characterization)

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13 pages, 811 KiB

Open AccessArticle

Analysis of the Models of Motion of Aqueous Solutions of Polymers on the Basis of Their Exact Solutions

by Oxana A. Frolovskaya^* and Vladislav V. Pukhnachev^*

Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk State University, 630090 Novosibirsk, Russia

Polymers 2018, 10(6), 684; https://doi.org/10.3390/polym10060684 - 19 Jun 2018

Cited by 19 | Viewed by 3675

Abstract

The qualitative properties of solutions of a hereditary model of motion of aqueous solutions of polymers, its modification in the limiting case of short relaxation times, and a similar second grade fluid model are studied. Unsteady shear flows are considered. In the first [...] Read more.

The qualitative properties of solutions of a hereditary model of motion of aqueous solutions of polymers, its modification in the limiting case of short relaxation times, and a similar second grade fluid model are studied. Unsteady shear flows are considered. In the first case, their properties are similar to those of motion of a usual viscous fluid. Other models can include weak discontinuities, which are retained in the course of fluid motion. Exact solutions are found by using the group analysis of the examined systems of equations. These solutions describe the fluid motion in a gap between coaxial rotating cylinders, the stagnation point flow, and the motion in a half-space induced by plane rotation (analog of the Karman vortex). The problem of motion of an aqueous solution of a polymer in a cylindrical tube under the action of a streamwise pressure gradient is considered. In this case, a flow with straight-line trajectories is possible (analog of the Hagen-Poiseuille flow). In contrast to the latter, however, the pressure in the flow considered here depends on all three spatial variables. Full article

(This article belongs to the Special Issue Polymer Dynamics)

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15 pages, 2568 KiB

Open AccessArticle

An Analytical Model of Interlaminar Fracture of Polymer Composite Reinforced by Carbon Fibres Grafted with Carbon Nanotubes

by Feng Xu¹, Hong-Yuan Liu² and Xusheng Du^3,*

¹ School of Astronautics, Northwestern Polytechnical University, Xi’an 710072, China

² Center for Advanced Materials Technology (CAMT), School of Aeronautics, Mechanical & Mechatronic Engineering J07, The University of Sydney, Sydney, NSW 2006, Australia

³ Institute of Advanced Wear & Corrosion Resistance and Functional Materials, Jinan University, Guangzhou 510632, China

Polymers 2018, 10(6), 683; https://doi.org/10.3390/polym10060683 - 19 Jun 2018

Cited by 23 | Viewed by 3581

Abstract

An analytical model was developed to study the interlaminar fracture behaviour of polymer composite reinforced by carbon fibres grafted with carbon nanotubes. Delamination properties, such as load with displacement or crack (R-curve) and toughness with crack (G_R-curve), can [...] Read more.

An analytical model was developed to study the interlaminar fracture behaviour of polymer composite reinforced by carbon fibres grafted with carbon nanotubes. Delamination properties, such as load with displacement or crack (R-curve) and toughness with crack (G_R-curve), can be obtained from this model. The bridging laws presented, based on the CNT pullout mechanism (CNT pullout from polymer matrix) and the CNT sword-in-sheath mechanism (CNT breakage), were incorporated into the proposed analytical model to investigate the influence of the structure of CNT growth onto CFs (CNT@CFs) on delamination properties. The numerical results showed that different toughening mechanisms led to different features of G_R-curves, R-curves, and load with displacement curves. Parametric study demonstrated that strengthening the CNT@CF interface resulted in significant improvement in toughness. Further, it was found that elastic deformation of CNTs played an important role in the toughness improvement in the CNT sword-in-sheath mechanism, but no such role was evident in the CNT pullout mechanism. Full article

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12 pages, 2476 KiB

Open AccessArticle

Sol-Gel Synthesis, Spectroscopic and Thermal Behavior Study of SiO₂/PEG Composites Containing Different Amount of Chlorogenic Acid

by Michelina Catauro^1,*

, Elisabetta Tranquillo^1,2, Roberta Risoluti³ and Stefano Vecchio Ciprioti⁴

¹ Department of Engineering, University of Campania “Luigi Vanvitelli”, Via Roma 29, I-81031 Aversa, Italy

² Department of Biochemistry, Biophysics and General Pathology, Medical School, University of Campania “Luigi Vanvitelli”, Via L. De Crecchio 7, 80138 Naples, Italy

³ Department of Chemistry—“Sapienza”, University of Rome, p.le A.Moro 5, 00185 Rome, Italy

⁴ Department S.B.A.I., Sapienza University of Rome, Via Del Castro Laurenziano 7, 00185 Rome, Italy

Polymers 2018, 10(6), 682; https://doi.org/10.3390/polym10060682 - 19 Jun 2018

Cited by 56 | Viewed by 6120

Abstract

In this work, new phenol-based materials have been synthesized by the sol-gel method, in which different amounts of the phenolic antioxidant chlorogenic acid (CGA) (from 5 wt % to 20 wt %) were embedded in two different silica matrices: pure silica and silica-based [...] Read more.

In this work, new phenol-based materials have been synthesized by the sol-gel method, in which different amounts of the phenolic antioxidant chlorogenic acid (CGA) (from 5 wt % to 20 wt %) were embedded in two different silica matrices: pure silica and silica-based hybrids materials, containing 50 wt % of polyethylene glycol (PEG). The incorporation of CGA in different sol-gel matrices might protect them from degradation, which could cause the loss of their properties. The two series of materials were chemically characterized by Fourier transform infrared (FTIR) spectroscopy. In addition, the thermal behavior of both series of materials containing CGA was studied by thermogravimetry under both air and inert N₂ flowing gas atmosphere. The bioactivity was evaluated by soaking the synthesized hybrids in a simulated body fluid, showing that the bioactivity of the silica matrix is not modified by the presence of PEG and CGA. Full article

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

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13 pages, 4089 KiB

Open AccessArticle

Fabric Coated with Shape Memory Polyurethane and Its Properties

by Md Anwar Jahid¹

, Jinlian Hu^1,*

, KwanHa Wong¹, You Wu¹, Yong Zhu², Hogan Hong Sheng Luo³

and Deng Zhongmin⁴

¹ Institute of Textile and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong 999077, China

² Shanghai Hiend Polyurethane, Inc., Jinshan District, Shanghai 201500, China

³ Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China

⁴ School of Textile Science and Engineering, Wuhan Textile University, Wuhan 430200, China

Polymers 2018, 10(6), 681; https://doi.org/10.3390/polym10060681 - 19 Jun 2018

Cited by 50 | Viewed by 9280

Abstract

In order to provide thermo-physiological comfort to the wearer, textile materials should have some functional property like water-resistance or water vapor transmission (WVT), so that perspiration can evaporate and be transmitted from the body surface to the environment even in extreme weather conditions [...] Read more.

In order to provide thermo-physiological comfort to the wearer, textile materials should have some functional property like water-resistance or water vapor transmission (WVT), so that perspiration can evaporate and be transmitted from the body surface to the environment even in extreme weather conditions that require wind and rain proof. Shape memory polyurethane (SMPU) could possibly be a candidate; it is a functional textile material that meets such requirements. In this research, we synthesized a series of SMPUs, which are responsive materials, to test whether these coated cotton fabrics could provide thermal insulation with lower permeability at low temperature or low relative humidity (RH), and high permeability at room temperature or above, or high relative humidity with its water-resistance property. In this paper, we have proposed a segmented shape memory polyurethane for coated textiles in order to have a water-resistant textile with good water vapor transmitting ability. Full article

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

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14 pages, 3345 KiB

Open AccessArticle

Centrifugally Spun Recycled PET: Processing and Characterization

by Phu Phong Vo^1,2, Hoan Ngoc Doan³

, Kenji Kinashi^4,*, Wataru Sakai⁴, Naoto Tsutsumi⁴

and Dai Phu Huynh²

¹ Internship Student, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan

² National Key Lab for Polymer and Composite, Faculty of Materials Technology, HoChiMinh City University of Technology, Vietnam National University, HoChiMinh City 700000, Vietnam

³ Doctor’s Program of Materials Chemistry, Graduate school of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan

⁴ Faculty of Materials Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan

Polymers 2018, 10(6), 680; https://doi.org/10.3390/polym10060680 - 19 Jun 2018

Cited by 39 | Viewed by 7702

Abstract

Centrifugal spinning, which is a high-productivity fiber fabrication technique, was used to produce a value-added product from recycled poly(ethylene terephthalate) (rPET). In the present study, rPET fibers, with fiber diameters ranging from submicron to micrometer in scale, were fabricated by spinning a solution [...] Read more.

Centrifugal spinning, which is a high-productivity fiber fabrication technique, was used to produce a value-added product from recycled poly(ethylene terephthalate) (rPET). In the present study, rPET fibers, with fiber diameters ranging from submicron to micrometer in scale, were fabricated by spinning a solution of rPET in a mixture of dichloromethane and trifluoroacetic acid. The influence of the polymer solution concentration (the viscosity), the rotational speed of the spinneret, and the inner diameter of the needles on the formation and morphology and mechanical properties of the fibers were examined through scanning electron microscopy and using a tensile testing machine. The thermal behaviors of fibrous mats with various average diameters were also investigated through differential scanning calorimetry. The smoothest and smallest fibers, with an average diameter of 619 nm, were generated using an rPET solution of 10 wt % under a rotation speed of 15,000 rpm using needles having an inner diameter of 160 μm. The fibrous mats have an average tensile strength and modulus of 4.3 MPa and 34.4 MPa, respectively. The productivity and the mechanical properties indicate that centrifugal spinning is an effective technique to fabricate high-value product from rPET. Full article

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16 pages, 10229 KiB

Open AccessArticle

Molecularly Imprinted Polymers for the Selective Extraction of Bisphenol A and Progesterone from Aqueous Media

by César Cáceres¹

, Catalina Bravo², Bernabé Rivas¹, Ewa Moczko³, Pedro Sáez⁴, Yadiris García² and Eduardo Pereira^2,*

¹ Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Edmundo Larenas #129, Concepción 4070371, Chile

² Departamento de Química Analítica e Inorgánica, Facultad de Ciencias Químicas, Universidad de Concepción, Edmundo Larenas #129, Concepción 4070371, Chile

³ Departamento de Química Ambiental, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Alonso de Rivera #2850, Concepción 4090541, Chile

⁴ Sección Microanálisis, Laboratorio de Criminalística Central, Policía de Investigaciones de Chile PDI, Carlos Silva Vidósola #9783, La Reina, Santiago 7860379, Chile

Polymers 2018, 10(6), 679; https://doi.org/10.3390/polym10060679 - 19 Jun 2018

Cited by 29 | Viewed by 5674

Abstract

This paper describes the development of a novel sorbent for selective extraction of endocrine disruptors (EDs) from aqueous media. The main goal was to obtain sufficient molecularly imprinted polymers (MIPs) for selective detection, preconcentration, and extraction of EDs such as bisphenol A (BPA) [...] Read more.

This paper describes the development of a novel sorbent for selective extraction of endocrine disruptors (EDs) from aqueous media. The main goal was to obtain sufficient molecularly imprinted polymers (MIPs) for selective detection, preconcentration, and extraction of EDs such as bisphenol A (BPA) and progesterone (PG). Series of MIPs and their analogues, non-molecularly imprinted polymers (NIPs), were synthesised following a non-covalent imprinting strategy based on radical polymerisation. Sets of synthesis were performed in order to optimise variables of the polymerisation including solvent, cross-linker, and template ratio. The retention capacity of MIPs was determined using HPLC in the range of 33.3% to 96.6% and 32.5% to 96% for BPA and PG, respectively. The adsorption mechanism was studied by isothermal and kinetic assays. The kinetic analysis showed a high retention capacity within 15 min of contact. The polymer yield was obtained in the range of 30% to 100%. Additionally, there was no significant cross-reactivity observed upon testing MIPs with structural analogues and other endocrine disruptors instead of target molecules. The results also revealed the high importance of different concentrations of cross-linker and solvent during the polymerisation. Firstly, the pre-organisation of complementary functional groups, which were present in the polymerisation mixture, and secondly, selective cavity formation for target molecules. Full article

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

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23 pages, 44886 KiB

Open AccessArticle

Finite-Element Investigation of the Structural Behavior of Basalt Fiber Reinforced Polymer (BFRP)- Reinforced Self-Compacting Concrete (SCC) Decks Slabs in Thompson Bridge

by Lingzhu Zhou^1,2, Yu Zheng^1,*

and Susan E. Taylor³

¹ School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523080, China

² Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

³ School of Natural and Built Environment, Queen’s University Belfast, Northern Ireland, BT9 5AG, UK

Polymers 2018, 10(6), 678; https://doi.org/10.3390/polym10060678 - 18 Jun 2018

Cited by 18 | Viewed by 4740

Abstract

The need for a sustainable development and improved whole life performance of concrete infrastructure has led to the requirement of more durable and sustainable concrete bridges alongside accurate predictive analysis tools. Using the combination of Self-Compacting Concrete (SCC) with industrial by-products and fiber-reinforced [...] Read more.

The need for a sustainable development and improved whole life performance of concrete infrastructure has led to the requirement of more durable and sustainable concrete bridges alongside accurate predictive analysis tools. Using the combination of Self-Compacting Concrete (SCC) with industrial by-products and fiber-reinforced polymer (FRP), reinforcement is anticipated to address the concerns of high carbon footprint and corrosion in traditional steel-reinforced concrete structures. This paper presents a numerical investigation of the structural behavior of basalt fiber-reinforced polymer (BFRP)-reinforced SCC deck slabs in a real bridge, named Thompson Bridge, constructed in Northern Ireland, U.K. A non-linear finite element (FE) model is proposed by using ABAQUS 6.10 in this study, which is aimed at extending the previous investigation of the field test in Thompson Bridge. The results of this field test were used to validate the accuracy of the proposed finite element model. The results showed good agreement between the test results and the numerical results; more importantly, the compressive membrane action (CMA) inside the slabs could be well demonstrated by this FE model. Subsequently, a series of parametric studies was conducted to investigate the influence of different parameters on the structural performance of the deck slabs in Thompson Bridge. The results of the analyses are discussed, and conclusions on the behavior of the SCC deck slabs reinforced by BFRP bars are presented. Full article

(This article belongs to the Special Issue Simulations of Polymers)

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15 pages, 4223 KiB

Open AccessArticle

Preparation of Compositional Gradient Polymeric Films Based on Gradient Mesh Template

by Honglei Teng¹, Jing Li¹, Zhaosheng Hou², Xilu Yan¹, Linru Han¹, Jing Xu^1,* and Tianduo Li^1,*

¹ Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Pharmaceutical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China

² College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250100, China

Polymers 2018, 10(6), 677; https://doi.org/10.3390/polym10060677 - 18 Jun 2018

Cited by 7 | Viewed by 4344

Abstract

In this paper, a template-filling method was found to prepare composition gradient gelatin films by incorporating α-[3-(2,3-epoxypropoxy) propyl]-ω-butyl-polydimethylsiloxane (PDMS–E) grafted gelatin (PGG) into a gradient gelatin mesh template. The method can be used to prepare other composition gradient biopolymer films. Gradient mesh template [...] Read more.

In this paper, a template-filling method was found to prepare composition gradient gelatin films by incorporating α-[3-(2,3-epoxypropoxy) propyl]-ω-butyl-polydimethylsiloxane (PDMS–E) grafted gelatin (PGG) into a gradient gelatin mesh template. The method can be used to prepare other composition gradient biopolymer films. Gradient mesh template prepared by the methacrylic anhydride cross-linked gelatin under temperature gradient field. The porosity of the template decreased from 89 to 35% which was accompanied by decrease in average pore size from 160 to 50 µm. Colloidal particles about 0.9~10 µm were formed from PGG after adding them to a mixed solvent system of 9:1 (v/v) of ethanol/water, which were filled in the mesh template under vacuum (0.06 MPa). A gradient film was obtained after drying at room temperature for 48 h. The results of scanning electron microscope-energy dispersive X-ray combined with freezing microtome and Fourier transform infrared spectroscopy suggested that the distribution of the Si element along the thickness showed a typical gradient pattern, which led to hydrophilic/hydrophobic continuous changing along the thickness of film. The water vapor permeability, thermal gravimetric analysis, differential scanning calorimetry and dynamic mechanical tensile results show that the gradient films had excellent water vapor permeability and flexibility, and hence could be used as biomimetic materials and leather finishing agents. Full article

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11 pages, 3012 KiB

Open AccessArticle

Critical Point Drying: An Effective Drying Method for Direct Measurement of the Surface Area of a Pretreated Cellulosic Biomass

by Kyu-Young Kang¹, Kyung-Ran Hwang², Ji-Yeon Park², Joon-Pyo Lee³, Jun-Seok Kim⁴ and Jin-Suk Lee^3,*

¹ Department of Biological and Environmental Science, Dongguk University-Seoul, 32 Dongguk-ro, Ilsandong-gu, Goyang 10326, Korea

² Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 34129, Korea

³ Gwangju Bioenergy R&D Center, Korea Institute of Energy Research, 25 Samso-ro270beongil, Buk-gu, Gwangju 61003, Korea

⁴ Department of Chemical Engineering, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon 16227, Korea

Polymers 2018, 10(6), 676; https://doi.org/10.3390/polym10060676 - 17 Jun 2018

Cited by 27 | Viewed by 8020

Abstract

The surface area and pore size distribution of Eucalyptus samples that were pretreated by different methods were determined by the Brunauer–Emmett–Teller (BET) technique. Three methods were applied to prepare cellulosic biomass samples for the BET measurements, air, freeze, and critical point drying (CPD). [...] Read more.

The surface area and pore size distribution of Eucalyptus samples that were pretreated by different methods were determined by the Brunauer–Emmett–Teller (BET) technique. Three methods were applied to prepare cellulosic biomass samples for the BET measurements, air, freeze, and critical point drying (CPD). The air and freeze drying caused a severe collapse of the biomass pore structures, but the CPD effectively preserved the biomass morphology. The surface area of the CPD prepared Eucalyptus samples were determined to be 58–161 m²/g, whereas the air and freeze dried samples were 0.5–1.3 and 1.0–2.4 m²/g, respectively. The average pore diameter of the CPD prepared Eucalyptus samples were 61–70 Å. The CPD preserved the Eucalyptus sample morphology by replacing water with a non-polar solvent, CO₂ fluid, which prevented hydrogen bond reformation in the cellulose. Full article

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13 pages, 4032 KiB

Open AccessArticle

Effect of a Surfactant in Microcapsule Synthesis on Self-Healing Behavior of Capsule Embedded Polymeric Films

by Jiyeon Lee^1,2,†, Seon Joo Park^2,†, Chul-Soon Park², Oh Seok Kwon², So Young Chung¹, Jongwon Shim¹, Chang-Soo Lee^2,3,* and Joonwon Bae^1,*

¹ Department of Applied Chemistry, Dongduk Women’s University, Seoul 02748, Korea

² Hazards Monitoring Bionano Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB) 125 Gwahak-Ro, Yuseong-Gu, Daejeon 34141, Korea

³ Nanobiotechnology (Major), University of Science & Technology (UST) 125 Gwahak-Ro, Yuseong-Gu, Daejeon 34141, Korea

^† These authors contributed equally to this work.

Polymers 2018, 10(6), 675; https://doi.org/10.3390/polym10060675 - 17 Jun 2018

Cited by 15 | Viewed by 6236

Abstract

Recently, there has been increased interest in self-healing membranes containing functional microcapsules in relation to challenges involving water treatment membranes. In this study, a self-healing membrane has been prepared by incorporating microcapsules with a polyurethane (PU) shell and a diisocyanate core in a [...] Read more.

Recently, there has been increased interest in self-healing membranes containing functional microcapsules in relation to challenges involving water treatment membranes. In this study, a self-healing membrane has been prepared by incorporating microcapsules with a polyurethane (PU) shell and a diisocyanate core in a poly(ether sulfone) (PES) membrane. Depending on the characteristics of the microcapsule, to precisely quantify the self-healing behavior and performance of the produced microcapsule embedded membranes, it is important to understand the effect of a used surfactant on microcapsule synthesis. It is noteworthy that mixed surfactants have been employed to control and tailor the size and morphology of microcapsules during the synthetic process, and the surfactant system employed was one of the most dominant parameters for affecting the healing capability of microcapsule embedded membranes. Various techniques including microscopy (optical and electron), thermal analyses (DSC and TGA), and water flux measurements have been employed. This article provides essential and important information for future research into the subtle relation between microcapsule properties with varied synthetic parameters and the self-healing behavior of membrane. Full article

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

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16 pages, 5699 KiB

Open AccessArticle

Polymer Optical Fiber Bragg Gratings in CYTOP Fibers for Angle Measurement with Dynamic Compensation

by Arnaldo Leal-Junior^1,*

, Antreas Theodosiou²

, Camilo Díaz¹, Carlos Marques³

, Maria José Pontes¹

, Kyriacos Kalli²

and Anselmo Frizera-Neto¹

¹ Graduate Program of Electrical Engineering of Federal University of Espirito Santo, 29075-910 Vitória, Brazil

² Photonics and Optical Sensing Research Laboratory, Cyprus University of Technology, Limassol 3036, Cyprus

³ Instituto de Telecomunicações, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

Polymers 2018, 10(6), 674; https://doi.org/10.3390/polym10060674 - 17 Jun 2018

Cited by 82 | Viewed by 5340

Abstract

This paper demonstrates the use of polymer optical fiber Bragg gratings (POFBGs) for angle measurements over a range of different oscillatory frequencies. The POFBGs are inscribed in low-loss, cyclic transparent amorphous fluoropolymers (CYTOP) and are imprinted using the direct-write, plane-by-plane femtosecond laser inscription [...] Read more.

This paper demonstrates the use of polymer optical fiber Bragg gratings (POFBGs) for angle measurements over a range of different oscillatory frequencies. The POFBGs are inscribed in low-loss, cyclic transparent amorphous fluoropolymers (CYTOP) and are imprinted using the direct-write, plane-by-plane femtosecond laser inscription method. As the polymer has a viscoelastic response and given that the Young’s modulus depends on the oscillatory frequency, a compensation technique for sensor frequency cross-sensitivity and hysteresis is proposed and verified. Results show that the proposed compensation technique is able to provide a root mean squared error (RMSE) reduction of 44%, and a RMSE as low as 2.20° was obtained when compared with a reference potentiometer. The hysteresis reduction provided by the proposed technique is 55%, with hysteresis <0.01. The results presented in this paper can pave the way for movement analysis with POFBG providing higher sensitivity and low hysteresis over a large range of motion frequencies. Full article

(This article belongs to the Special Issue Holographic Materials and Photonic Applications)

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13 pages, 2482 KiB

Open AccessArticle

Wound Dressings Based on Chitosan-Dialdehyde Cellulose Nanocrystals-Silver Nanoparticles: Mechanical Strength, Antibacterial Activity and Cytotoxicity

by Feng Dong^1,2

and Shujun Li^1,*

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

² Light Industry and Textile School, Qiqihar University, Qiqihar 161006, China

Polymers 2018, 10(6), 673; https://doi.org/10.3390/polym10060673 - 16 Jun 2018

Cited by 56 | Viewed by 6993

Abstract

The present work envisages a simple approach to synthesize a new wound dressing based on chitosan-dialdehyde cellulose nanocrystal-silver nanoparticles (CS-DCNC-AgNPs). Silver nanoparticles (AgNPs) were generated in-situ by periodate oxidation of cellulose nanocrystals to generate aldehyde functions, which were used to reduce Ag⁺ [...] Read more.

The present work envisages a simple approach to synthesize a new wound dressing based on chitosan-dialdehyde cellulose nanocrystal-silver nanoparticles (CS-DCNC-AgNPs). Silver nanoparticles (AgNPs) were generated in-situ by periodate oxidation of cellulose nanocrystals to generate aldehyde functions, which were used to reduce Ag⁺ into Ag⁰ in mild alkaline conditions. Subsequently, the dialdehyde cellulose nanocrystal-silver nanoparticles (DCNC-AgNPs) were added to chitosan (CS) to form the wound dressings by solution casting method. The aim was to enhance the antibacterial effect of CS by incorporation of AgNPs and to improve the mechanical strength and hydrophobicity of CS by incorporation of DCNC that cross-linked by hydrogen bonds. The antibacterial activities were evaluated against five gram-negative bacteria, one gram-positive bacteria, and three fungi. The in vitro cytotoxicity assay was performed using the NIH3T3 cell lines by Sulforhodamine B assay. Research outputs signified that CS-DCNC-AgNPs possessed good mechanical strength and hydrophobicity, high antibacterial activity and less cytotoxicity. Our results propose that CS-DCNC-AgNPs can be a promising, safe antibacterial to be incorporated in wound dressings. Full article

(This article belongs to the Special Issue Polysaccharides)

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21 pages, 6038 KiB

Open AccessArticle

On the Mechanisms of the Effects of Ionizing Radiation on Diblock and Random Copolymers of Poly(Lactic Acid) and Poly(Trimethylene Carbonate)

by Agnieszka Adamus-Wlodarczyk¹, Radoslaw A. Wach^1,*, Piotr Ulanski¹, Janusz M. Rosiak¹, Marta Socka², Zois Tsinas³ and Mohamad Al-Sheikhly³

¹ Institute of Applied Radiation Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland

² Department of Polymer Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland

³ Department of Materials Science and Engineering, University of Maryland, 4418 Stadium Dr., College Park, MD 20742-2115, USA

Polymers 2018, 10(6), 672; https://doi.org/10.3390/polym10060672 - 16 Jun 2018

Cited by 21 | Viewed by 5841

Abstract

This article demonstrates that ionizing radiation induces simultaneous crosslinking and scission in poly(trimethylene carbonate-co-d-lactide) diblock and random copolymers. Copolymer films were electron-beam (EB) irradiated up to 300 kGy under anaerobic conditions and subsequently examined by evaluation of their structure [...] Read more.

This article demonstrates that ionizing radiation induces simultaneous crosslinking and scission in poly(trimethylene carbonate-co-d-lactide) diblock and random copolymers. Copolymer films were electron-beam (EB) irradiated up to 300 kGy under anaerobic conditions and subsequently examined by evaluation of their structure (FT-IR, NMR), molecular weight, intrinsic viscosities, and thermal properties. Radiation chemistry of the copolymers is strongly influenced by the content of ester linkages of the lactide component. At low lactide content, crosslinking reaction is the dominant one; however, as the lactide ratio increases, the ester linkages scission becomes more competent and exceeds the crosslinking. Electron paramagnetic resonance (EPR) measurements indicate that higher content of amorphous carbonate units in copolymers leads to a reduction in free radical yield and faster radical decay as compared to lactide-rich compositions. The domination of scission of ester bonds was confirmed by identifying the radiolytically produced alkoxyl and acetyl radicals, the latter being more stable due to its conjugated structure. Full article

(This article belongs to the Special Issue Radiation Effects in Polymers)

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11 pages, 3773 KiB

Open AccessArticle

A Numerical and Experimental Study on a Pre-Twisted Ring Spinning System

by Keyi Wang^1,2, Wenliang Xue^1,2 and Longdi Cheng^1,2,*

¹ Key Laboratory of Textile Science & Technology, Ministry of Education, Donghua University, Shanghai 201620, China

² College of Textiles, Donghua University, Shanghai 201620, China

Polymers 2018, 10(6), 671; https://doi.org/10.3390/polym10060671 - 16 Jun 2018

Cited by 5 | Viewed by 5247

Abstract

The ring spinning process is the most widely used method in the spinning industry. Nowadays, the labor cost become more and more expensive, and it is essential to improve productivity. For increasing the productivity, a modification of adding a pre-twister and holding roller [...] Read more.

The ring spinning process is the most widely used method in the spinning industry. Nowadays, the labor cost become more and more expensive, and it is essential to improve productivity. For increasing the productivity, a modification of adding a pre-twister and holding roller on the traditional ring spinning system have been discussed in this paper. The computational fluid dynamics (CFD) are introduced to study the effects of pre-twister and spinning tests are implemented for verification. The numerical simulations show that the cavity conical degree and nozzle numbers of the pre-twister are the key parameters which affect the airflow fluctuation in the cavity, and have obvious effects on the resultant yarn twist. By contrast, the axial angle and tangential angle of the nozzle have less effect on the resultant yarn twist. When the fiber bundles pass by the front nip, they are affected by the vortex and result in a partially strengthened and wrapped structure which could be subsequently twisted less by the traveler and ring, so the productivity could be potentially increased. According to the spinning tests, an evident productivity increase by nearly 30% for medium cotton yarns can be achieved, and the yarns have an acceptable reduction in nearly all properties. Full article

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

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14 pages, 4662 KiB

Open AccessArticle

Modification of Alkali Lignin with Poly(Ethylene Glycol) Diglycidyl Ether to Be Used as a Thickener in Bio-Lubricant Formulations

by Esperanza Cortés-Triviño

, Concepción Valencia

, Miguel A. Delgado and José M. Franco^*

Pro2TecS-Chemical Product and Process Technology Centre, University of Huelva, 21071 Huelva, Spain

Polymers 2018, 10(6), 670; https://doi.org/10.3390/polym10060670 - 16 Jun 2018

Cited by 36 | Viewed by 7090

Abstract

Considerable efforts are currently being made by the academic community and industry, aiming to develop environmentally friendly lubricants with suitable technical features for their performance. In this context, lignin could be considered a promising candidate to be used as a bio-sourced thickening agent [...] Read more.

Considerable efforts are currently being made by the academic community and industry, aiming to develop environmentally friendly lubricants with suitable technical features for their performance. In this context, lignin could be considered a promising candidate to be used as a bio-sourced thickening agent to formulate eco-friendly lubricating greases. In this work, alkali lignin (AL) was chemically modified with poly(ethylene glycol) diglycidyl ether (PEGDE). Afterwards, the epoxidized lignin was properly dispersed in castor oil (CO) in order to obtain an oleogel for lubricant applications. The epoxidized lignins were characterized by means of epoxy index determination, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The epoxide-functionalized lignin-based oleogels were analyzed from both rheological and tribological points of view. It was found that the viscosity, consistency and viscoelastic functions of these oleogels clearly increased with the epoxy index of the epoxide-modified lignin compound. Thermo-rheological characterization of these oleogels revealed a slight thermal dependence of the viscoelastic moduli below 100 °C, but a significant softening above that critical temperature. In general, these oleogels showed low values of the friction coefficient under the mixed lubrication regime as compared to the neat castor oil. Full article

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

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14 pages, 3836 KiB

Open AccessArticle

Heterogeneous Catalytic Composites from Palladium Nanoparticles in Montmorillonite Intercalated with Poly (Vinyl Pyrrolidone) Chains

by Mengdie Xu, Jing Zhao, Guiqing Shu, Qi Liu and Minfeng Zeng^*

Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, College of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China

Polymers 2018, 10(6), 669; https://doi.org/10.3390/polym10060669 - 15 Jun 2018

Cited by 10 | Viewed by 4189

Abstract

In this study, poly (vinyl pyrrolidone) (PVP) chains intercalated montmorillonite (MMT) matrices has been demonstrated as an excellent scaffolding material for the immobilization of palladium (Pd) nanoparticles to prepare efficient heterogeneous catalysts for Heck reactions. Multiple layers (up to four) of PVP chains [...] Read more.

In this study, poly (vinyl pyrrolidone) (PVP) chains intercalated montmorillonite (MMT) matrices has been demonstrated as an excellent scaffolding material for the immobilization of palladium (Pd) nanoparticles to prepare efficient heterogeneous catalysts for Heck reactions. Multiple layers (up to four) of PVP chains can intercalate the interlayer space of the MMT, resulting in an increase therein from 1.25 to 3.22 nm. MMT/PVP with PVP loading (20%) was selected as the platform for the immobilization of Pd. The in-situ reduction of the chelated Pd²⁺ into Pd⁰ in the interlayer space of MMT/PVP composite could be easily achieved. For the prepared Pd@MMT/PVP catalytic composite, a unique maze-like microstructure of Pd nanoparticles tightly encaged by PVP chains and by lamellae of layered silica has been detected by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). Furthermore, the microstructure is well elucidated in molecular level by positron annihilation lifetime analysis of the Pd@MMT/PVP catalytic composite. The prepared Pd@MMT/PVP catalysts were highly active for the Heck coupling reactions between aromatic halides and alkenes, and could be recycled 9 times without significant decreases in coupling yields. The excellent comprehensive catalytic performances of the Pd@MMT/PVP catalytic composites are mainly attributed to their unique maze-like microstructure. Full article

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

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18 pages, 6555 KiB

Open AccessArticle

Visco-Hyperelastic Model with Damage for Simulating Cyclic Thermoplastic Elastomers Behavior Applied to an Industrial Component

by Rafael Tobajas¹, Daniel Elduque^2,*

, Elena Ibarz³, Carlos Javierre², Alfonso F. Canteli⁴ and Luis Gracia³

¹ Department of Mechanical Engineering, University of Zaragoza, C/María de Luna, 3, 50018 Zaragoza, Spain

² i+aitiip, Department of Mechanical Engineering, University of Zaragoza, C/María de Luna, 3, 50018 Zaragoza, Spain

³ i3A, Department of Mechanical Engineering, University of Zaragoza, C/María de Luna, 3, 50018 Zaragoza, Spain

⁴ Department of Construction and Manufacturing Engineering, University of Oviedo, C/Pedro Puig Adam, 33203 Gijón, Spain

Polymers 2018, 10(6), 668; https://doi.org/10.3390/polym10060668 - 15 Jun 2018

Cited by 14 | Viewed by 5697

Abstract

In this work a nonlinear phenomenological visco-hyperelastic model including damage consideration is developed to simulate the behavior of Santoprene 101-73 material. This type of elastomeric material is widely used in the automotive and aeronautic sectors, as it has multiple advantages. However, there are [...] Read more.

In this work a nonlinear phenomenological visco-hyperelastic model including damage consideration is developed to simulate the behavior of Santoprene 101-73 material. This type of elastomeric material is widely used in the automotive and aeronautic sectors, as it has multiple advantages. However, there are still challenges in properly analyzing the mechanical phenomena that these materials exhibit. To simulate this kind of material a lot of theories have been exposed, but none of them have been endorsed unanimously. In this paper, a new model is presented based on the literature, and on experimental data. The test samples were extracted from an air intake duct component of an automotive engine. Inelastic phenomena such as hyperelasticity, viscoelasticity and damage are considered singularly in this model, thus modifying and improving some relevant models found in the literature. Optimization algorithms were used to find out the model parameter values that lead to the best fit of the experimental curves from the tests. An adequate fitting was obtained for the experimental results of a cyclic uniaxial loading of Santoprene 101-73. Full article

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17 pages, 8430 KiB

Open AccessArticle

Effect of Graphene Nano-Additives on the Local Mechanical Behavior of Derived Polymer Nanocomposites

by Mostapha Tarfaoui^1,2,*

, Khalid Lafdi², Imane Beloufa¹, Debora Daloia² and Ali Muhsan²

¹ ENSTA Bretagne, IRDL—UMR CNRS 6027, F-29200 Brest, France

² University of Dayton, Dayton, OH 45469-0168, USA

Polymers 2018, 10(6), 667; https://doi.org/10.3390/polym10060667 - 15 Jun 2018

Cited by 20 | Viewed by 5117

Abstract

In this study, indentation tests of graphene-based polymer nanocomposites were carried out to determine the local elastic mechanical properties. The samples consist of epoxy matrix with graphene additives. Additives were added at levels of 0% as a control, 0.5%, 1%, 2.5%, 5% and [...] Read more.

In this study, indentation tests of graphene-based polymer nanocomposites were carried out to determine the local elastic mechanical properties. The samples consist of epoxy matrix with graphene additives. Additives were added at levels of 0% as a control, 0.5%, 1%, 2.5%, 5% and 10% by weight. The local elastic properties such as moduli and hardness were calculated. After each indentation, the prints were characterized using scanning electron microscopy (SEM). It seems that the local mechanical properties of nanocomposite samples were improved as the amount of nano-additives increased. Based on the curve displacement and surface imaging, we can conclude that the nano-additives influenced the overall plastic mechanical behavior of the samples. For simulating micro-indentation test, a finite element analysis model was developed using ABAQUS software and compared to experimental tests. Good correlation was observed. Full article

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

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18 pages, 7269 KiB

Open AccessArticle

Fused Deposition Modeling of ABS-Barium Titanate Composites: A Simple Route towards Tailored Dielectric Devices

by Bilal Khatri^1,*

, Karl Lappe¹, Mathis Habedank¹, Tobias Mueller², Christof Megnin³ and Thomas Hanemann^1,3

¹ Laboratory for Materials Processing, University of Freiburg, 79110 Freiburg, Germany

² Institute of Automation and Applied Informatics, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany

³ Institute of Applied Materials, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany

Polymers 2018, 10(6), 666; https://doi.org/10.3390/polym10060666 - 14 Jun 2018

Cited by 95 | Viewed by 9215

Abstract

A process for the development, characterization and correlation of composite materials for 3D printing is presented, alongside the processing of a polymer-ceramic functional composite using fused deposition modeling (FDM). The composite was developed using acrylonitrile butadiene styrene (ABS) as the matrix material filled [...] Read more.

A process for the development, characterization and correlation of composite materials for 3D printing is presented, alongside the processing of a polymer-ceramic functional composite using fused deposition modeling (FDM). The composite was developed using acrylonitrile butadiene styrene (ABS) as the matrix material filled with barium titanate (BT) micro-powder up to 35 vol % (74.2 wt %). The ABS-BT composites exhibited a shear thinning behavior with increasing ceramic content. The composite was 3D printed into structural and functional test samples using FDM by adapting and optimizing the print parameters. Structural characterization revealed increasingly brittle behavior at higher filler ratios, with the ultimate tensile strength falling from 25.5 MPa for pure ABS to 13.7 MPa for the ABS-35 vol % BT composite. Four-point flexural tests showed a similar decrease in flexural strength with increasing ceramic content. Functional characterization revealed an increase in the relative permittivity at 200 kHz from 3.08 for pure ABS to 11.5 for the composite with 35 vol % BT. These results were correlated with the Maxwell-Garnett and Jayasundere-Smith effective medium models. The process described in this work can be used for other 3D printing processes and provides a framework for the rapid prototyping of functional composites into functional parts with reliable properties. The ABS-BT composite shows promise as a functional dielectric material, with potential applications as capacitors and light-weight passive antennas. Full article

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25 pages, 7092 KiB

Open AccessArticle

Trithiocarbonate-Functionalized PNiPAAm-Based Nanocomposites for Antimicrobial Properties

by Milène Tan

, Lenke Horvàth, Priscilla S. Brunetto

and Katharina M. Fromm^*

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

Polymers 2018, 10(6), 665; https://doi.org/10.3390/polym10060665 - 14 Jun 2018

Cited by 3 | Viewed by 5413

Abstract

In this study, four trithiocarbonate-functionalized PNiPAAms with different molecular weights were synthesized and used as a matrix to form composites with silver nanoparticles. Nanocomposites with several polymer-to-silver ratios P:Ag⁺ were prepared in order to evaluate the influence of silver loading. UV studies [...] Read more.

In this study, four trithiocarbonate-functionalized PNiPAAms with different molecular weights were synthesized and used as a matrix to form composites with silver nanoparticles. Nanocomposites with several polymer-to-silver ratios P:Ag⁺ were prepared in order to evaluate the influence of silver loading. UV studies showed a thermoresponsive behavior of the nanocomposites with a thermo-reversibility according to cooling-heating cycles. Release kinetics demonstrated that the release of silver ions is mainly influenced by the size of the silver nanoparticles (AgNPs), which themselves depend on the polymer length. Antimicrobial tests against E. coli and S. aureus showed that some of the nanocomposites are antimicrobial and even full killing could be induced. Full article

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13 pages, 4089 KiB

Open AccessArticle

Preparation and Properties of 3D Printed Alginate–Chitosan Polyion Complex Hydrogels for Tissue Engineering

by Qiongqiong Liu^1,2, Qingtao Li^1,2, Sheng Xu^2,3, Qiujian Zheng^4,* and Xiaodong Cao^2,3,*

¹ School of Medicine, South China University of Technology, 382 Outer Ring Rd, Guangzhou 510006, China

² National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, 382 Outer Ring Rd, Guangzhou 510006, China

³ School of Material Science and Engineering, South China University of Technology, 381 Wushan Rd, Guangzhou 510641, China

⁴ Guangdong General Hospital, 106 Zhongshan Second Rd, Guangzhou 510080, China

Polymers 2018, 10(6), 664; https://doi.org/10.3390/polym10060664 - 14 Jun 2018

Cited by 179 | Viewed by 14479

Abstract

Three-dimensional (3D) printing holds great potential for preparing sophisticated scaffolds for tissue engineering. As a result of the shear thinning properties of an alginate solution, it is often used as 3D printing ink. However, it is difficult to prepare scaffolds with complexity structure [...] Read more.

Three-dimensional (3D) printing holds great potential for preparing sophisticated scaffolds for tissue engineering. As a result of the shear thinning properties of an alginate solution, it is often used as 3D printing ink. However, it is difficult to prepare scaffolds with complexity structure and high fidelity, because the alginate solution has a low viscosity and alginate hydrogels prepared with Ca²⁺ crosslinking are mechanically weak. In this work, chitosan powders were dispersed and swelled in an alginate solution, which could effectively improve the viscosity of an alginate solution by 1.5–4 times. With the increase of chitosan content, the shape fidelity of the 3D printed alginate–chitosan polyion complex (AlCh PIC) hydrogels were improved. Scanning electron microscope (SEM) photographs showed that the lateral pore structure of 3D printed hydrogels was becoming more obvious. As a result of the increased reaction ion pairs in comparison to the alginate hydrogels that were prepared with Ca²⁺ crosslinking, AlCh PIC hydrogels were mechanically strong, and the compression stress of hydrogels at a 90% strain could achieve 1.4 MPa without breaking. In addition, human adipose derived stem cells (hASCs) adhered to the 3D printed AlCh PIC hydrogels and proliferated with time, which indicated that the obtained hydrogels were biocompatible and could potentially be used as scaffolds for tissue engineering. Full article

(This article belongs to the Collection Polysaccharides)

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19 pages, 1332 KiB

Open AccessReview

Compression Garments for Medical Therapy and Sports

by Ying Xiong¹ and Xiaoming Tao^1,2,*

¹ Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China

² Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China

Polymers 2018, 10(6), 663; https://doi.org/10.3390/polym10060663 - 14 Jun 2018

Cited by 117 | Viewed by 19859

Abstract

Compression garments are elastic clothing with an engineered compression gradient that can be worn on limbs, upper, lower, or full body to use for therapy and sports. This article presents an overview and review on the compression garments and concentrates on the design [...] Read more.

Compression garments are elastic clothing with an engineered compression gradient that can be worn on limbs, upper, lower, or full body to use for therapy and sports. This article presents an overview and review on the compression garments and concentrates on the design of compression garments with an appropriate pressure for specific applications. It covers the types of compression garments, fibers and yarns, knitted fabric construction, garment design, an evaluation system, and pressure measurement and modeling. The material properties, fabric properties, pressure modeling, and the garment design system presents the prediction, design, and fabrication of the compression garments. Lastly, the research status and directions are discussed. Full article

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

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13 pages, 3026 KiB

Open AccessArticle

Synthesis and Characterization of Poly(1,4,7-Trioxacycloundecane-8,11-dione) Macrocyclic Functionalized Hydrogel for High Selectivity Adsorption and Complexation of Bismuth Ion

by Brian A. Omondi^1,2,*

, Hirotaka Okabe^1,2, Yoshiki Hidaka^1,2

and Kazuhiro Hara^1,2

¹ Department of Applied Quantum Physics and Nuclear Engineering, Faculty of Engineering, West 2, 922-2, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan

² Center for Research and Education of Environmental Technology, Faculty of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan

Polymers 2018, 10(6), 662; https://doi.org/10.3390/polym10060662 - 13 Jun 2018

Cited by 5 | Viewed by 3646

Abstract

Macrocyclic functional hydrogels incorporating new poly cyclic active sites (1,4,7-trioxacycloundecane-8,11-dione) within their entire network, have been synthesized. Using the high-dilution coupling of the bi-functional monomers maleic acid and bis(chloroethyl)ether in a sol-gel chemistry synthesis, 11-membered chelate rings infused with three oxygen donor atoms [...] Read more.

Macrocyclic functional hydrogels incorporating new poly cyclic active sites (1,4,7-trioxacycloundecane-8,11-dione) within their entire network, have been synthesized. Using the high-dilution coupling of the bi-functional monomers maleic acid and bis(chloroethyl)ether in a sol-gel chemistry synthesis, 11-membered chelate rings infused with three oxygen donor atoms were created and characterized, and their structures confirmed using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic analyses. The macrocyclic gel, designed for selective host-guest adsorption and complexation of metal substrates, was initially tested against an aqueous set of 14 metal competitive solutions, where it demonstrated exclusive selectivity for Bi³⁺_aq, with the other metals exhibiting zero adsorption. Further analysis using binary and single ion Bi³⁺-containing solutions showed a near-complete removal of Bi³⁺ using this polycyclic hydrogel, with 98% extraction efficiency and q = 9.80 mg/g. These results clearly confirm that the 1,4,7-trioxacycloundecane-8,11-dione cyclic sites are most suitable for high selectivity and capture of Bi. The metal substrates were entrapped within the 1,4,7-trioxacycloundecane-8,11-dione cyclic sites. Evidently, by exploiting the host-guest complexation chemistry of macrocycles, we were able to design hydrogel adsorbents whose networks were comprised entirely of macrocyclic active groups for possible purification works of copper involving bismuth impurities, and/or for efficient selective uptake and recovery of bismuth trace ions existing in highly competitive environments such as sea water. Full article

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12 pages, 4713 KiB

Open AccessArticle

Tensile Creep Behavior of Quasi-Unidirectional E-Glass Fabric Reinforced Polypropylene Composite

by Zhanyu Zhai^1,*, Bingyan Jiang² and Dietmar Drummer¹

¹ Institute of Polymer Technology, University Erlangen-Nuremberg, 91054 Erlangen, Germany

² State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Lushan South Road 932, 410083 Changsha, China

Polymers 2018, 10(6), 661; https://doi.org/10.3390/polym10060661 - 13 Jun 2018

Cited by 18 | Viewed by 6075

Abstract

The present work addressed the creep behavior of quasi-unidirectional E-glass fabric reinforced polypropylene composites under off-axis tensile loading. A series of creep tests were performed on the composite at three different loading stress levels. The creep response of off-axis samples of quasi-unidirectional composites [...] Read more.

The present work addressed the creep behavior of quasi-unidirectional E-glass fabric reinforced polypropylene composites under off-axis tensile loading. A series of creep tests were performed on the composite at three different loading stress levels. The creep response of off-axis samples of quasi-unidirectional composites under a constant loading level can be clearly observed. A phenomenological viscoplasticity model was built for describing the creep behavior of the composite. To improve the accuracy of prediction, cyclic loading-unloading tests were adopted to determine the material constants in the model. The predicted results in terms of the strains after a load over a period of time were found to be satisfactory, compared with the experimental results. In addition, same failure mechanism was found in off-axis samples under quasi-static and creep loading cases. Full article

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15 pages, 2908 KiB

Open AccessArticle

pH-Responsive Hybrid Hydrogels as Antibacterial and Drug Delivery Systems

by Shabnam Sattari, Abbas Dadkhah Tehrani and Mohsen Adeli^*

Department of Chemistry, Faculty of Science, Lorestan University, Khorramabad P.O. Box 465, Iran

Polymers 2018, 10(6), 660; https://doi.org/10.3390/polym10060660 - 13 Jun 2018

Cited by 62 | Viewed by 7673

Abstract

This study describes the design and synthesis of organic–inorganic hybrid hydrogels based on an interpenetrating polymer network (IPN) composed of polyaspartic acid crosslinked by graphene nanosheets as the primary network and poly(acrylamide-co-acrylic acid) as the secondary network. Silver, copper oxide, and zinc oxide [...] Read more.

This study describes the design and synthesis of organic–inorganic hybrid hydrogels based on an interpenetrating polymer network (IPN) composed of polyaspartic acid crosslinked by graphene nanosheets as the primary network and poly(acrylamide-co-acrylic acid) as the secondary network. Silver, copper oxide, and zinc oxide nanoparticles were formed within the gel matrix, and the obtained hydrogel was applied to a load and controlled release of curcumin. The loading of curcumin and the release of this drug from the gels depended on the nanoparticle’s (NP’s) content of hydrogels as well as the pH of the medium. The synthesized hydrogels showed antibacterial activity against E. coli and S. aureus bacteria. The ability of the synthesized hydrogels to incapacitate bacteria and their loading capacity and controlled release of curcumin qualify them for future therapies such as wound-dressing applications. Full article

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

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Polymers, Volume 10, Issue 6 (June 2018) – 126 articles

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