Polymers

15 pages, 5624 KiB

Open AccessArticle

Effects of Covalent Functionalization of MWCNTs on the Thermal Properties and Non-Isothermal Crystallization Behaviors of PPS Composites

by Myounguk Kim¹, Jungmin Lee¹, Hyun-gyoo Roh¹, Dahyun Kim¹, Juhee Byeon¹ and Jongshin Park^1,2,*

¹ Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 08826, Korea

² Research Institute for Agriculture and Life Sciences, Seoul 08826, Korea

Polymers 2017, 9(10), 460; https://doi.org/10.3390/polym9100460 - 21 Sep 2017

Cited by 14 | Viewed by 5711

Abstract

In this study, a PPS/MWCNTs composite was prepared with poly(phenylene sulfide) (PPS), as well as pristine and covalent functionalized multi-walled carbon nanotubes (MWCNTs) via melt-blending techniques. Moreover, the dispersion of the MWCNTs on the PPS matrix was improved by covalent functionalization as can [...] Read more.

In this study, a PPS/MWCNTs composite was prepared with poly(phenylene sulfide) (PPS), as well as pristine and covalent functionalized multi-walled carbon nanotubes (MWCNTs) via melt-blending techniques. Moreover, the dispersion of the MWCNTs on the PPS matrix was improved by covalent functionalization as can be seen from a Field-Emission Scanning Electron Microscope (FE-SEM) images. The thermal properties of the PPS/MWCNTs composites were characterized using a thermal conductivity analyzer, and a differential scanning calorimeter (DSC). To analyze the crystallization behavior of polymers under conditions similar with those in industry, the non-isothermal crystallization behaviors of the PPS/MWCNTs composites were confirmed using various kinetic equations, such as the modified Avrami equation and Avrami-Ozawa combined equation. The crystallization rate of PPS/1 wt % pristine MWCNTs composite (PPSP1) was faster because of the intrinsic nucleation effect of the MWCNTs. However, the crystallization rates of the composites containing covalently-functionalized MWCNTs were slower than PPSP1 because of the destruction of the MWCNTs graphitic structure via covalent functionalization. Furthermore, the activation energies calculated by Kissinger’s method were consistently decreased by covalent functionalization. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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14 pages, 2320 KiB

Open AccessArticle

Fabrication of Electrospun Polylactic Acid/Cinnamaldehyde/β-Cyclodextrin Fibers as an Antimicrobial Wound Dressing

by Yaowen Liu^1,2,*,†, Xue Liang^1,†, Rong Zhang¹, Wenting Lan¹ and Wen Qin¹

¹ College of Food Science, Sichuan Agricultural University, Yaan 625014, China

² School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China

^† These authors contributed equally to the work.

Polymers 2017, 9(10), 464; https://doi.org/10.3390/polym9100464 - 21 Sep 2017

Cited by 75 | Viewed by 7311

Abstract

Cinnamaldehyde (CA) was successfully encapsulated in β-cyclodextrin (β-CD), and polylactic acid (PLA)-based composite fibers were prepared by incorporating CA/β-CD via electrospinning. Morphological, structural, spectral, and antibacterial properties of different weight ratios of PLA:β-CD/CA (88:12, 94:6, 97:3, and 98.5:1.5) and PLA/CA/β-CD fibers were investigated. [...] Read more.

Cinnamaldehyde (CA) was successfully encapsulated in β-cyclodextrin (β-CD), and polylactic acid (PLA)-based composite fibers were prepared by incorporating CA/β-CD via electrospinning. Morphological, structural, spectral, and antibacterial properties of different weight ratios of PLA:β-CD/CA (88:12, 94:6, 97:3, and 98.5:1.5) and PLA/CA/β-CD fibers were investigated. PLA and CA/β-CD were incorporated by mixing of CA/β-CD inclusions to enhance the viscosity of the mixed solution. The mechanical properties and hydrophilicity of nanofibers were improved following the addition of CA/β-CD. Moreover, CA/β-CD improved the antibacterial activities of the mixture against Escherichia coli and Staphylococcus aureus. PLA/CA/β-CD-3 exhibited excellent antibacterial effects and low cytotoxicity. Thus, our study showed that PLA/CA/β-CD fibers may have applications as wound dressing materials and for use in other biomedical applications. Full article

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15 pages, 8082 KiB

Open AccessArticle

Shape Memory Polyurethanes Based on Zwitterionic Hard Segments

by Shuqin Fu^1,2,3, Huanhuan Ren³, Zaochuan Ge³, Haitao Zhuo^1,* and Shaojun Chen^3,*

¹ Shenzhen Key Laboratory of Functional Polymer, College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China

² Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

³ Guangdong Research Center for Interfacial Engineering of Functional Materials, Shenzhen Key Laboratory of Polymer Science and Technology, Shenzhen Key Laboratory of Special Functional Materials, Nanshan District Key Lab for Biopolymers and Safety Evaluation, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China

Polymers 2017, 9(10), 465; https://doi.org/10.3390/polym9100465 - 21 Sep 2017

Cited by 20 | Viewed by 6203

Abstract

This work aimed at elucidating the influence of zwitterionic hard segments on the structures and properties of shape memory polyurethanes (SMPUs). A series of zwitterionic SMPUs was successfully prepared with N-methyldiethanolamine (MDEA), 1,3-propanesultone (1,3-PS), 1,6-hexamethylene diisocyanate (HDI) and polyethylene glycol (PEG6000). The [...] Read more.

This work aimed at elucidating the influence of zwitterionic hard segments on the structures and properties of shape memory polyurethanes (SMPUs). A series of zwitterionic SMPUs was successfully prepared with N-methyldiethanolamine (MDEA), 1,3-propanesultone (1,3-PS), 1,6-hexamethylene diisocyanate (HDI) and polyethylene glycol (PEG6000). The influence of MDEA-PS-based zwitterionic hard segment on structure, morphology, thermal property, shape memory property and cytocompatibility were systematically investigated. The results demonstrated that the PEG-based zwitterionic SMPUs (PEG-ZSMPUs) formed phase separation structure consisting of crystalline soft phase and amorphous hard phase. The MDEA-PS zwitterionic segments showed a tendency to form ionic clusters in hard segments, which served as reinforced net points. Shape memory analysis showed that zwitterionic PEG-ZSMPUs containing a high content of zwitterionic segments had thermal-induced shape memory effects. Finally, cytotoxic assays demonstrated that MDEA-PS zwitterionic segment improved the biocompatibility of PEG-ZSMPUs. The zwitterionic PEG-ZSMPUs could thus have a promising application in smart biomedical fields. Full article

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

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13 pages, 2456 KiB

Open AccessArticle

Surface Properties and Structural Transformation Behaviors of mPEG-Maleic Rosin Copolymer in Water

by Juying Zhou^1,2,3,*, Xia Zhang¹, Yanzhi Zhao^1,2, Haitang Xu^1,2,3, Pengfei Li^1,2, Hao Li^1,2, Jinyan Zhang¹, Qin Huang^1,2,3 and Fuhou Lei^1,2

¹ School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning 530006, China

² Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning 530006, China

³ Key Laboratory of Guangxi Colleges and Universities for Food Safety and Pharmaceutical Analytical Chemistry, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning 530006, China

Polymers 2017, 9(10), 466; https://doi.org/10.3390/polym9100466 - 21 Sep 2017

Cited by 7 | Viewed by 5190

Abstract

mPEG (monomethoxy poly(ethylene glycol))-maleic rosin copolymer was successfully prepared. The surface properties of the copolymer were investigated by surface tension and resonance scattering techniques. The critical micelle concentration (CMC) was obtained. The adsorption behaviors and the conformational changes of the surfactant molecules at [...] Read more.

mPEG (monomethoxy poly(ethylene glycol))-maleic rosin copolymer was successfully prepared. The surface properties of the copolymer were investigated by surface tension and resonance scattering techniques. The critical micelle concentration (CMC) was obtained. The adsorption behaviors and the conformational changes of the surfactant molecules at the air-water interface were described. The adsorption amount of state 1 presented a sinusoid shape and that of state 2 presented a sigmoid with the growth of П. The free energy of adsorption is more negative than that of micellization, thus, the surfactant molecules adsorb on the surface firstly, and then form micelles after saturation adsorption. Accordingly, structural transformation and aggregation behaviors of various concentration mPEG-maleic rosin copolymers with changing temperature were explored in water. The mPEG-maleic rosin chains experienced transformation from unimers to aggregates, to contracted aggregates, to cohesive aggregates with increasing temperature when the concentration is lower than CMC. This process is almost reversible with decreasing temperature. Transformation from micelle to aggregate with increasing temperature happened when the concentration is higher than CMC. The phenomena were assessed by DLS (dynamic light scattering) and SEM (scanning electron microscopy) techniques. Full article

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10 pages, 2805 KiB

Open AccessArticle

Enhanced Performance of Nanoporous Titanium Dioxide Solar Cells Using Cadmium Sulfide and Poly(3-hexylthiophene) Co-Sensitizers

by Murugathas Thanihaichelvan¹, Minidu Manoranjana Punya Sri Kodikara¹, Punniyamoorthy Ravirajan^1,*

and Dhayalan Velauthapillai²

¹ Department of Physics, Faculty of Science, University of Jaffna, Jaffna 40000, Sri Lanka

² Faculty of Engineering, Campus Bergen, Western Norway University of Applied Sciences, P.O. Box 7030, 5020 Bergen, Norway

Polymers 2017, 9(10), 467; https://doi.org/10.3390/polym9100467 - 22 Sep 2017

Cited by 9 | Viewed by 5349

Abstract

This work reports the effect of co-sensitization of nanoporous titanium dioxide using Cadmium Sulfide (CdS) and poly(3-hexylthiophene) (P3HT) on the performance of hybrid solar cells. CdS nanolayer with different thicknesses was grown on Titanium Dioxide (TiO₂) nanoparticles by chemical bath deposition [...] Read more.

This work reports the effect of co-sensitization of nanoporous titanium dioxide using Cadmium Sulfide (CdS) and poly(3-hexylthiophene) (P3HT) on the performance of hybrid solar cells. CdS nanolayer with different thicknesses was grown on Titanium Dioxide (TiO₂) nanoparticles by chemical bath deposition technique with varying deposition times. Both atomic force microscopy (AFM) and UV–Vis–NIR spectroscopy measurements of TiO₂ electrode sensitized with and without CdS layer confirm that the existence of CdS layer on TiO₂ nanoparticles. AFM images of CdS-coated TiO₂ nanoparticles show that the surface roughness of the TiO₂ nanoparticle samples decreases with increasing CdS deposition times. Current density–voltage and external quantum efficiency (EQE) measurements were carried out for corresponding solar cells. Both short circuit current density (J_SC) and fill factor were optimized at the CdS deposition time of 12 min. On the other hand, a steady and continuous increment in the open circuit voltage (V_OC) was observed with increasing CdS deposition time and increased up to 0.81 V when the deposition time was 24 min. This may be attributed to the increased gradual separation of P3HT and TiO₂ phases and their isolation at the interfaces. The higher V_OC of 0.81 V was due to the higher built-in voltage at the CdS–P3HT interface when compared to that at the TiO₂–P3HT interface. Optimized nanoporous TiO₂ solar cells with CdS and P3HT co-sensitizers showed external quantum efficiency (EQE) of over 40% and 80% at the wavelengths corresponding to strong absorption of the polymer and CdS, respectively. The cells showed an overall average efficiency of over 2.4% under the illumination of 70 mW/cm² at AM 1.5 condition. Full article

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

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12 pages, 5351 KiB

Open AccessArticle

pH-Mediated Antibacterial Dyeing of Cotton with Prodigiosins Nanomicelles Produced by Microbial Fermentation

by Jixian Gong^1,2,*,†, Yanfei Ren^1,2,†, Ranran Fu¹, Zheng Li^1,2

and Jianfei Zhang^1,2,*

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

² Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China

^† These authors contributed equally and mainly to this study. Yanfei Ren should be regarded as joint first authors.

Polymers 2017, 9(10), 468; https://doi.org/10.3390/polym9100468 - 23 Sep 2017

Cited by 37 | Viewed by 7434

Abstract

This study developed a novel pH-mediated antimicrobial dyeing process of cotton with prodigiosins nanomicelles produced by microbial fermentation. The average diameter of the pigment nanomicelles was 223.8 nm (range of 92.4–510.2 nm), and the pigment concentration was 76.46 mg/L. It was found that [...] Read more.

This study developed a novel pH-mediated antimicrobial dyeing process of cotton with prodigiosins nanomicelles produced by microbial fermentation. The average diameter of the pigment nanomicelles was 223.8 nm (range of 92.4–510.2 nm), and the pigment concentration was 76.46 mg/L. It was found that the superior dyeing effect of cotton fabric was achieved by adjusting the dye bath pH. When the pH was three, dyed cotton under 90 °C for 60 min exhibited the greatest color strength with good rubbing, washing and perspiration color fastness. By the breaking strength test and XRD analysis, it was concluded that the cotton dyed under the optimum condition almost suffered no damage. In addition, due to the presence of prodigiosins, dyed cotton fabric under the optimal process showed outstanding bacteriostatic rates of 99.2% and 85.5% against Staphylococcus aureus and Escherichia coli, respectively. This research provided an eco-friendly and widely-applicable approach for antimicrobial intracellular pigments with the property of pH-sensitive solubility in water to endow cellulose fabric with color and antibacterial activity. Full article

(This article belongs to the Special Issue Antimicrobial Polymers)

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16 pages, 2742 KiB

Open AccessArticle

Fabrication of Hypericin Imprinted Polymer Nanospheres via Thiol-Yne Click Reaction

by Yuxin Pei^*

, Fengfeng Fan, Xinxin Wang

, Weiwei Feng, Yong Hou and Zhichao Pei^*

Shanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling 712100, Shaanxi, China

Polymers 2017, 9(10), 469; https://doi.org/10.3390/polym9100469 - 24 Sep 2017

Cited by 12 | Viewed by 5871

Abstract

To fabricate molecularly imprinted polymer nanospheres via click reaction, five different clickable compounds were synthesized and two types of click reactions (azide-alkyne and thiol-yne) were explored. It was found that molecularly imprinted polymer nanospheres could be successfully synthesized via thiol-yne click reaction using [...] Read more.

To fabricate molecularly imprinted polymer nanospheres via click reaction, five different clickable compounds were synthesized and two types of click reactions (azide-alkyne and thiol-yne) were explored. It was found that molecularly imprinted polymer nanospheres could be successfully synthesized via thiol-yne click reaction using 3,5-diethynyl-pyridine (1) as the monomer, tris(3-mercaptopropionate) (tri-thiol, 5) as the crosslinker, and hypericin as the template (MIP–NSHs). The click polymerization completed in merely 4 h to produce the desired MIP–NSHs, which were characterized by FTIR, SEM, DLS, and BET, respectively. The reaction conditions for adsorption capacity and selectivity towards hypericin were optimized, and the MIP–NSHs synthesized under the optimized conditions showed a high adsorption capacity (Q = 6.03 μmol•g−1) towards hypericin. The imprinting factors of MIP–NSHs towards hypericin, protohypericin, and emodin were 2.44, 2.88, and 2.10, respectively. Full article

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

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30 pages, 8377 KiB

Open AccessReview

Precise Synthesis of Macromolecular Architectures by Novel Iterative Methodology Combining Living Anionic Polymerization with Specially Designed Linking Chemistry

by Raita Goseki^1,2,*, Shotaro Ito¹, Yuri Matsuo¹, Tomoya Higashihara³ and Akira Hirao^1,4,5,*

¹ Polymeric and Organic Materials Department, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1, Ohokayama, Meguro-ku, Tokyo 152-8552, Japan

² Department of Chemical Science and Engineering, School of Materials Chemistry and Technology, Tokyo Institute of Technology, 2-12-1, Ohokayama, Meguro-ku, Tokyo 152-8552, Japan

³ Department of Polymer Science and Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan

⁴ Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan

⁵ Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan

Polymers 2017, 9(10), 470; https://doi.org/10.3390/polym9100470 - 25 Sep 2017

Cited by 40 | Viewed by 8222

Abstract

This article reviews the development of a novel all-around iterative methodology combining living anionic polymerization with specially designed linking chemistry for macromolecular architecture syntheses. The methodology is designed in such a way that the same reaction site is always regenerated after the polymer [...] Read more.

This article reviews the development of a novel all-around iterative methodology combining living anionic polymerization with specially designed linking chemistry for macromolecular architecture syntheses. The methodology is designed in such a way that the same reaction site is always regenerated after the polymer chain is introduced in each reaction sequence, and this “polymer chain introduction and regeneration of the same reaction site” sequence is repeatable. Accordingly, the polymer chain can be successively and, in principle, limitlessly introduced to construct macromolecular architectures. With this iterative methodology, a variety of synthetically difficult macromolecular architectures, i.e., multicomponent μ-star polymers, high generation dendrimer-like hyperbranched polymers, exactly defined graft polymers, and multiblock polymers having more than three blocks, were successfully synthesized. Full article

(This article belongs to the Special Issue Living Polymerization)

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29 pages, 13767 KiB

Open AccessFeature PaperArticle

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk

by Silvio Poppe^1,†, Marco Poppe^1,†, Helgard Ebert¹, Marko Prehm¹, Changlong Chen², Feng Liu², Stefan Werner³, Kirsten Bacia³

and Carsten Tschierske^1,*

¹ Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle, Germany

² State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China

³ Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 3, 06120 Halle, Germany

^† These authors contributed equally.

Polymers 2017, 9(10), 471; https://doi.org/10.3390/polym9100471 - 26 Sep 2017

Cited by 20 | Viewed by 8363

Abstract

Polyphilic self-assembly leads to compartmentalization of space and development of complex structures in soft matter on different length scales, reaching from the morphologies of block copolymers to the liquid crystalline (LC) phases of small molecules. Whereas block copolymers are known to form membranes [...] Read more.

Polyphilic self-assembly leads to compartmentalization of space and development of complex structures in soft matter on different length scales, reaching from the morphologies of block copolymers to the liquid crystalline (LC) phases of small molecules. Whereas block copolymers are known to form membranes and interact with phospholipid bilayers, liquid crystals have been less investigated in this respect. Here, series of bolapolyphilic X-shaped molecules were synthesized and investigated with respect to the effect of molecular structural parameters on the formation of LC phases (part 1), and on domain formation in phospholipid bilayer membranes (part 2). The investigated bolapolyphiles are based on a rod-like π-conjugated oligo(phenylene ethynylene) (OPE) core with two glycerol groups being either directly attached or separated by additional ethylene oxide (EO) units to both ends. The X-shape is provided by two lateral alkyl chains attached at opposite sides of the OPE core, being either linear, branched, or semiperfluorinated. In this report, the focus is on the transition from polyphilic (triphilic or tetraphilic) to binary amphiphilic self-assembly. Polyphilic self-assembly, i.e., segregation of all three or four incorporated units into separate nano-compartments, leads to the formation of hexagonal columnar LC phases, representing triangular honeycombs. A continuous transition from the well-defined triangular honeycomb structures to simple hexagonal columnar phases, dominated by the arrangement of polar columns on a hexagonal lattice in a mixed continuum formed by the lipophilic chains and the OPE rods, i.e., to amphiphilic self-assembly, was observed by reducing the length and volume of the lateral alkyl chains. A similar transition was found upon increasing the length of the EO units involved in the polar groups. If the lateral alkyl chains are enlarged or replaced by semiperfluorinated chains, then the segregation of lateral chains and rod-like cores is retained, even for enlarged polar groups, i.e., the transition from polyphilic to amphiphilic self-assembly is suppressed. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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35 pages, 12466 KiB

Open AccessReview

The Chemistry and Physics of Bayfol^® HX Film Holographic Photopolymer

by Friedrich-Karl Bruder^*, Thomas Fäcke and Thomas Rölle

Covestro Deutschland AG, Building D201, D-51365 Leverkusen, Germany

Polymers 2017, 9(10), 472; https://doi.org/10.3390/polym9100472 - 26 Sep 2017

Cited by 140 | Viewed by 13999

Abstract

Holographic photopolymers are a new technology to create passive diffractive optical elements by a pure laser interference recording. In this review, we explain the chemistry concepts of light harvesting in an interference pattern and the subsequent grating formation as chemical response. Using the [...] Read more.

Holographic photopolymers are a new technology to create passive diffractive optical elements by a pure laser interference recording. In this review, we explain the chemistry concepts of light harvesting in an interference pattern and the subsequent grating formation as chemical response. Using the example of the newly developed Bayfol^® HX film we discuss the reaction-diffusion driven photo-polymerization process for an index modulation formation to create volume phase gratings. Further we elucidate the selection of monomer chemistry and discuss details of the recording conditions based on the concept of exposure dosage and exposure time. Influences ranging from high dosage recording to low power recording are explained and how to affect the desired diffraction efficiency. Finally, we outline and demonstrate the process to mass manufacturing of volume phase gratings. Full article

(This article belongs to the Special Issue Photo-Responsive Polymers)

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11 pages, 2223 KiB

Open AccessArticle

Imidazole, a New Tunable Reagent for Producing Nanocellulose, Part I: Xylan-Coated CNCs and CNFs

by Jia Mao^1,2, Hatem Abushammala^1,2, Hubert Hettegger³

, Thomas Rosenau³

and Marie-Pierre Laborie^1,2,*

¹ Chair of Forest Biomaterials, Faculty of Environment and Natural Resources, Albert-Ludwig-University of Freiburg, Werthmannstr 6, 79085 Freiburg, Germany

² FIT-Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany

³ Division of Chemistry of Renewables Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria

Polymers 2017, 9(10), 473; https://doi.org/10.3390/polym9100473 - 27 Sep 2017

Cited by 23 | Viewed by 6168

Abstract

Imidazole is reported to be an effective reactant for the production of nanocellulose from hardwood pulp. The morphologies and surface properties of the nanocellulose can be simply tailored according to the water content in the imidazole system: with pure imidazole, cellulose nanofibrils (CNFs) [...] Read more.

Imidazole is reported to be an effective reactant for the production of nanocellulose from hardwood pulp. The morphologies and surface properties of the nanocellulose can be simply tailored according to the water content in the imidazole system: with pure imidazole, cellulose nanofibrils (CNFs) in a yield of 10 wt % can be produced. With 25 wt % of water in imidazole, cellulose nanocrystals (CNCs) are obtained in 20 wt % yield. Both nanocelluloses exhibit crystallinity indices in the order of 70%. Interestingly, they retain the original xylan from the pulp with ca. 9–10 wt % of residual xylan content. Full article

(This article belongs to the Special Issue Cellulose Nanomaterials)

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18 pages, 3740 KiB

Open AccessArticle

Design of a Versatile pH-Responsive Hydrogel for Potential Oral Delivery of Gastric-Sensitive Bioactives

by Angus R. Hibbins, Pradeep Kumar

, Yahya E. Choonara

, Pierre P. D. Kondiah, Thashree Marimuthu

, Lisa C. Du Toit and Viness Pillay^*

Wits Advanced Drug Delivery Platform Research Unit, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, School of Therapeutics Sciences, University of the Witwatersrand, Johannesburg, 7 York Road, Parktown 2193, South Africa

Polymers 2017, 9(10), 474; https://doi.org/10.3390/polym9100474 - 27 Sep 2017

Cited by 47 | Viewed by 11593

Abstract

A pH-responsive hydrogel system was prepared by free radical polymerization of acrylamide and methyl acrylic acid in the presence of N-N′-methylene bisacrylamide. Sodium bicarbonate was further applied as a blowing agent, which afforded a porous hydrogel structure. The hydrogel system [...] Read more.

A pH-responsive hydrogel system was prepared by free radical polymerization of acrylamide and methyl acrylic acid in the presence of N-N′-methylene bisacrylamide. Sodium bicarbonate was further applied as a blowing agent, which afforded a porous hydrogel structure. The hydrogel system achieved a constant super swelling rate within simulated intestinal buffer (~4%/min) and remained relatively static within simulated gastric buffer (~0.8%/min). The hydrogel system was able to achieve matrix resilience greater than 30% under a relatively high strain of 40%. In addition, the hydrogel system demonstrated significant swelling properties in response to simulated intestinal environmental over 24 h, with contrasting characteristics in simulated gastric buffer. The hydrogel demonstrated type IV isotherm porosity characteristics, with remarkable MRI and SEM variations in gastric and intestinal simulated fluids. Drug loading was observed to be greater than 98% using theophylline as a prototype drug, evaluating its controlled release kinetics over 24 h. The hydrogel exhibited substantial pH-responsive activity, which could be used as a versatile platform for targeted release of gastric-sensitive therapeutics to the small intestine. Full article

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

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11 pages, 2297 KiB

Open AccessArticle

Synthesis of Polystyrene–Polyphenylsiloxane Janus Particles through Colloidal Assembly with Unexpected High Selectivity: Mechanistic Insights and Their Application in the Design of Polystyrene Particles with Multiple Polyphenylsiloxane Patches

by Daniel Mann^1,2, Stefanie Voogt^1,2,3, Helmut Keul^1,2, Martin Möller^1,2, Marcel Verheijen^4,5 and Pascal Buskens^1,2,3,6,*

¹ DWI—Leibniz Institute for Interactive Materials e.V., Forckenbeckstr. 50, 52056 Aachen, Germany

² Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

³ Zuyd University of Applied Sciences, Nieuw Eyckholt 300, Postbus 550, 6400 AN Heerlen, The Netherlands

⁴ Philips Innovation Labs, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands

⁵ Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

⁶ The Netherlands Organisation for Applied Scientific Research (TNO), De Rondom 1, 5612 AP Eindhoven, The Netherlands

Polymers 2017, 9(10), 475; https://doi.org/10.3390/polym9100475 - 28 Sep 2017

Cited by 11 | Viewed by 6175

Abstract

Janus particles are of great research interest because of their reduced symmetry, which provides them with unique physical and chemical properties. Such particles can be prepared from spherical structures through colloidal assembly. Whilst colloidal assembly has the potential to be a low cost [...] Read more.

Janus particles are of great research interest because of their reduced symmetry, which provides them with unique physical and chemical properties. Such particles can be prepared from spherical structures through colloidal assembly. Whilst colloidal assembly has the potential to be a low cost and scalable process, it typically lacks selectivity. As a consequence, it results in a complex mixture of particles of different architectures, which is tedious to purify. Very recently, we reported the colloidal synthesis of Au semishells, making use of polystyrene–polyphenylsiloxane Janus particles as an intermediate product (Chem. Commun. 2017, 53, 3898–3901). Here, we demonstrate that these Janus particles are realized through colloidal assembly of spherical glucose-functionalized polystyrene particles and an emulsion of phenyltrimethoxysilane in aqueous ammonia, followed by interfacial polycondensation to form the polyphenylsiloxane patch. Both the polystyrene spheres and the emulsion of Ph-TMS in aqueous ammonia are stabilized by a surfmer—a reactive surfactant. The colloidal assembly reported in this manuscript proceeds with an unexpected high selectivity, which makes this process exceptionally interesting for the synthesis of Janus particles. Furthermore, we report insights into the details of the mechanism of formation of these Janus particles, and apply those to adapt the synthesis conditions to produce polystyrene particles selectively decorated with multiple polyphenylsiloxane patches, e.g., raspberry particles. Full article

(This article belongs to the Collection Silicon-Containing Polymeric Materials)

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14 pages, 2910 KiB

Open AccessFeature PaperArticle

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behavior. Part 2: Domain Formation by Self-Assembly in Lipid Bilayer Membranes

by Stefan Werner¹, Jan Ebenhan¹, Marco Poppe², Silvio Poppe², Helgard Ebert², Carsten Tschierske²

and Kirsten Bacia^1,*

¹ Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle, Germany

² Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany

Polymers 2017, 9(10), 476; https://doi.org/10.3390/polym9100476 - 29 Sep 2017

Cited by 3 | Viewed by 4898

Abstract

Supramolecular self-assembly of membrane constituents within a phospholipid bilayer creates complex functional platforms in biological cells that operate in intracellular signaling, trafficking and membrane remodeling. Synthetic polyphilic compounds of macromolecular or small size can be incorporated into artificial phospholipid bilayers. Featuring three or [...] Read more.

Supramolecular self-assembly of membrane constituents within a phospholipid bilayer creates complex functional platforms in biological cells that operate in intracellular signaling, trafficking and membrane remodeling. Synthetic polyphilic compounds of macromolecular or small size can be incorporated into artificial phospholipid bilayers. Featuring three or four moieties of different philicities, they reach beyond ordinary amphiphilicity and open up avenues to new functions and interaction concepts. Here, we have incorporated a series of X-shaped bolapolyphiles into DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) bilayers of giant unilamellar vesicles. The bolapolyphiles consist of a rod-like oligo(phenylene ethynylene) (OPE) core, hydrophilic glycerol-based headgroups with or without oligo(ethylene oxide) expansions at both ends and two lateral alkyl chains attached near the center of the OPE core. In the absence of DPPC and water, the compounds showed thermotropic liquid-crystalline behavior with a transition between polyphilic and amphiphilic assembly (see part 1 in this issue). In DPPC membranes, various trends in the domain morphologies were observed upon structure variations, which entailed branched alkyl chains of various sizes, alkyl chain semiperfluorination and size expansion of the headgroups. Observed effects on domain morphology are interpreted in the context of the bulk behavior (part 1) and of a model that was previously developed based on spectroscopic and physicochemical data. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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1 pages, 128 KiB

Open AccessErratum

Erratum: Correlation-Based Multiplexing of Complex Amplitude Data Pages in a Holographic Storage System Using Digital Holographic Techniques. Polymers, 2017, 9, 375

by Teruyoshi Nobukawa^1,* and Takanori Nomura²

¹ Graduate School of Systems Engineering, Wakayama University, 930 Sakaedani, Wakayama 640-8510, Japan

² Faculty of Systems Engineering, Wakayama University, 930 Sakaedani, Wakayama 640-8510, Japan

Polymers 2017, 9(10), 477; https://doi.org/10.3390/polym9100477 - 29 Sep 2017

Viewed by 2398

Abstract

The authors wish to make a change to the published paper [1].[...] Full article

11 pages, 5250 KiB

Open AccessArticle

Supported Ionic Liquid Silica as Curing Agent for Epoxy Composites with Improved Mechanical and Thermal Properties

by Chongrui Zhang¹, Xiaoqian Mi¹, Junyu Tian¹, Junheng Zhang^1,* and Tiwen Xu^2,*

¹ Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission & Ministry of Education, South-Central University for Nationalities, Wuhan 430074, China

² School of Chemical Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China

Polymers 2017, 9(10), 478; https://doi.org/10.3390/polym9100478 - 29 Sep 2017

Cited by 24 | Viewed by 6906

Abstract

The present study aims to improve the mechanical properties of epoxy composite by incorporating supported ionic liquid silica (IL-silica). The IL-silica not only showed improved interfacial interaction and reinforcement, but also served as cure agent of epoxy composites. The differential scanning calorimetry analysis [...] Read more.

The present study aims to improve the mechanical properties of epoxy composite by incorporating supported ionic liquid silica (IL-silica). The IL-silica not only showed improved interfacial interaction and reinforcement, but also served as cure agent of epoxy composites. The differential scanning calorimetry analysis revealed that epoxy composites could be successfully cured with IL-silica without any routine curing agents. IL-silica/epoxy composites presented higher mechanical and thermal properties compared with epoxy composite containing un-functionalized silica (u-silica). The dynamic mechanical analysis showed that the storage modulus of composites significantly increased with the addition of IL-silica in comparison to that with added u-silica, as well as the variation of Tg parameter. The incorporation of IL-silica simultaneously enhanced the tensile strength, toughness, and thermal stability of the epoxy composites. The considerable improvements in mechanical and thermal properties are ascribed to the improved dispersion of IL-silica and the enhanced interfacial interactions between epoxy matrix and IL-silica by strong covalent bonding, which results in an effective load transfer. Full article

(This article belongs to the Collection Silicon-Containing Polymeric Materials)

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15 pages, 3839 KiB

Open AccessArticle

Biocompatible Silk/Polymer Energy Harvesters Using Stretched Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) Nanofibers

by Raghid Najjar¹, Yi Luo², Dave Jao³, David Brennan³, Ye Xue³, Vince Beachley³, Xiao Hu^3,4

and Wei Xue^1,*

¹ Mechanical Engineering, Rowan University, Glassboro, NJ 08028, USA

² Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, China

³ Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA

⁴ Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA

Polymers 2017, 9(10), 479; https://doi.org/10.3390/polym9100479 - 30 Sep 2017

Cited by 27 | Viewed by 11130

Abstract

Energy harvested from human body movement can produce continuous, stable energy to portable electronics and implanted medical devices. The energy harvesters need to be light, small, inexpensive, and highly portable. Here we report a novel biocompatible device made of poly (vinylidene fluoride-co [...] Read more.

Energy harvested from human body movement can produce continuous, stable energy to portable electronics and implanted medical devices. The energy harvesters need to be light, small, inexpensive, and highly portable. Here we report a novel biocompatible device made of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers on flexible substrates. The nanofibers are prepared with electrospinning followed by a stretching process. This results in aligned nanofibers with diameter control. The assembled device demonstrates high mechanical-to-electrical conversion performance, with stretched PVDF-HFP nanofibers outperforming regular electrospun samples by more than 10 times. Fourier transform infrared spectroscopy (FTIR) reveals that the stretched nanofibers have a higher β phase content, which is the critical polymorph that enables piezoelectricity in polyvinylidene fluoride (PVDF). Polydimethylsiloxane (PDMS) is initially selected as the substrate material for its low cost, high flexibility, and rapid prototyping capability. Bombyx Mori silkworm silk fibroin (SF) and its composites are investigated as promising alternatives due to their high strength, toughness, and biocompatibility. A composite of silk with 20% glycerol demonstrates higher strength and larger ultimate strain than PDMS. With the integration of stretched electrospun PVDF-HFP nanofibers and flexible substrates, this pilot study shows a new pathway for the fabrication of biocompatible, skin-mountable energy devices. Full article

(This article belongs to the Special Issue Protein Biopolymer)

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14 pages, 6986 KiB

Open AccessArticle

Effect of Aging, Antioxidant, and Mono- and Divalent Ions at High Temperature on the Rheology of New Polyacrylamide-Based Co-Polymers

by Saeed Akbari^1,*

, Syed M. Mahmood^2,*

, Isa M. Tan³, Onn Lin Ling⁴ and Hosein Ghaedi⁵

¹ Centre of Research in Enhanced Oil Recovery (COREOR), Petroleum Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar, 32610 Tronoh, Malaysia

² Shale Gas Research Group (SGRG), Institute of Hydrocarbon Recovery, Petroleum Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar, 32610 Tronoh, Malaysia

³ Fundamental and Applied Science, Universiti Teknologi PETRONAS, Seri Iskandar, 32610 Tronoh, Malaysia

⁴ Petroleum Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar, 32610 Tronoh, Malaysia

⁵ Chemical Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar, 32610 Tronoh, Malaysia

Polymers 2017, 9(10), 480; https://doi.org/10.3390/polym9100480 - 4 Oct 2017

Cited by 17 | Viewed by 6872

Abstract

The viscosity of four new polymers was investigated for the effect of aging at high temperature, with varying degrees of salinity and hardness. The four sulfonated based polyacrylamide co-polymers were FLOCOMB C7035; AN132 VHM; SUPERPUSHER SAV55; and THERMOASSOCIATIF copolymers. All polymer samples were [...] Read more.

The viscosity of four new polymers was investigated for the effect of aging at high temperature, with varying degrees of salinity and hardness. The four sulfonated based polyacrylamide co-polymers were FLOCOMB C7035; AN132 VHM; SUPERPUSHER SAV55; and THERMOASSOCIATIF copolymers. All polymer samples were aged at 80 °C for varying times (from zero to at least 90 days) with and without isobutyl alcohol (IBA) as an antioxidant. To see the effect of divalent ions on the polymer solution viscosity, parallel experiments were performed in a mixture of CaCl₂-NaCl of the same ionic strength as 5 wt % NaCl. The polymers without IBA showed severe viscosity reduction after aging for 90 days in both types of preparation (5 wt % NaCl or CaCl₂-NaCl). In the presence of IBA, viscosity was increased when aging time was increased for 5 wt % NaCl. In CaCl₂-NaCl, on the other hand, a viscosity reduction was observed as aging time was increased. This behavior was observed for all polymers except AN132 VHM. Full article

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14 pages, 2060 KiB

Open AccessArticle

Polystyrene Chain Growth from Di-End-Functional Polyolefins for Polystyrene-Polyolefin-Polystyrene Block Copolymers

by Chung Sol Kim, Seung Soo Park, Sung Dong Kim, Su Jin Kwon, Jun Won Baek

and Bun Yeoul Lee^*

Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea

Polymers 2017, 9(10), 481; https://doi.org/10.3390/polym9100481 - 2 Oct 2017

Cited by 13 | Viewed by 9387

Abstract

Triblock copolymers of polystyrene (PS) and a polyolefin (PO), e.g., PS-block-poly(ethylene-co-1-butene)-block-PS (SEBS), are attractive materials for use as thermoplastic elastomers and are produced commercially by a two-step process that involves the costly hydrogenation of PS-block-polybutadiene- [...] Read more.

Triblock copolymers of polystyrene (PS) and a polyolefin (PO), e.g., PS-block-poly(ethylene-co-1-butene)-block-PS (SEBS), are attractive materials for use as thermoplastic elastomers and are produced commercially by a two-step process that involves the costly hydrogenation of PS-block-polybutadiene-block-PS. We herein report a one-pot strategy for attaching PS chains to both ends of PO chains to construct PS-block-PO-block-PS directly from olefin and styrene monomers. Dialkylzinc compound containing styrene moieties ((CH₂=CHC₆H₄CH₂CH₂)₂Zn) was prepared, from which poly(ethylene-co-propylene) chains were grown via “coordinative chain transfer polymerization” using the pyridylaminohafnium catalyst to afford di-end functional PO chains functionalized with styrene and Zn moieties. Subsequently, PS chains were attached at both ends of the PO chains by introduction of styrene monomers in addition to the anionic initiator Me₃SiCH₂Li·(pmdeta) (pmdeta = pentamethyldiethylenetriamine). We found that the fraction of the extracted PS homopolymer was low (~20%) and that molecular weights were evidently increased after the styrene polymerization (ΔM_n = 27–54 kDa). Transmission electron microscopy showed spherical and wormlike PS domains measuring several tens of nm segregated within the PO matrix. Optimal tensile properties were observed for the sample containing a propylene mole fraction of 0.25 and a styrene content of 33%. Finally, in the cyclic tensile test, the prepared copolymers exhibited thermoplastic elastomeric properties with no breakage up over 10 cycles, which is comparable to the behavior of commercial-grade SEBS. Full article

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

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13 pages, 3650 KiB

Open AccessArticle

QCM Biosensor Based on Polydopamine Surface for Real-Time Analysis of the Binding Kinetics of Protein-Protein Interactions

by Chunli Wu^1,†, Xueming Li^2,†, Siyu Song², Yuxin Pei²

, Lili Guo² and Zhichao Pei^2,*

¹ School of Pharmaceutical Sciences, Zhengzhou University, 100 Kexue Avenue, Zhengzhou 450001, China

² Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A & F University, Yangling 712100, China

^† These authors contributed equally to this work.

Polymers 2017, 9(10), 482; https://doi.org/10.3390/polym9100482 - 2 Oct 2017

Cited by 20 | Viewed by 11321

Abstract

A quartz crystal microbalance (QCM) biosensor based on polydopamine (PDA) surface was developed for real-time analysis of the binding kinetics of protein-protein interactions. The biosensor was fabricated by simply immersing the gold sensor chip into an aqueous dopamine solution at pH 8.5 leading [...] Read more.

A quartz crystal microbalance (QCM) biosensor based on polydopamine (PDA) surface was developed for real-time analysis of the binding kinetics of protein-protein interactions. The biosensor was fabricated by simply immersing the gold sensor chip into an aqueous dopamine solution at pH 8.5 leading to a spontaneous deposition of PDA film onto the sensor chip surface, which was followed by incubation with the protein to immobilize it onto the PDA-coated sensor chip surface via Michael addition and/or Schiff base reactions. In this paper, the interaction between monoclonal anti-myoglobin 7005 antibody (IgG1) and its antigen human cardiac myoglobin was used as a model system for real-time analysis of biomolecule interactions on the biosensor surface. The kinetic parameters of the interaction between anti-myoglobin 7005 and myoglobin were studied on the biosensor surface, which were consistent with the results obtained via amine coupling. The biosensor based on PDA surface has excellent regenerability, reproducibility, and specificity. Compared with the most frequently/typically used amine coupling method for immobilization of proteins on carboxylated substrates, the modification methodology presented in this paper is simple, mild and is not subjected to the limitations of the isoelectric point (pI) of the protein. In addition, the PDA biosensor chip can be easily reused, which makes QCM biosensor analysis more efficient and cost effective. Full article

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9 pages, 948 KiB

Open AccessCommunication

Vesicles in Multiple Shapes: Fine-Tuning Polymersomes’ Shape and Stability by Setting Membrane Hydrophobicity

by Jens Gaitzsch^1,*, Lea Messager², Eloise Morecroft³ and Wolfgang Meier^1,*

¹ Departement of Chemistry, University of Basel, Mattenstrasse 24a, BPR1096, 4058 Basel, Switzerland

² LAGEP-Université Claude Bernard Lyon 1, 43 Boulevard du 11 novembre 1918, Bâtiment CPE-308G, M69622 Villeurbanne Cedex, France

³ Institute of Chemical Biology, Exhibition Road, London SW7 2AZ, UK

Polymers 2017, 9(10), 483; https://doi.org/10.3390/polym9100483 - 2 Oct 2017

Cited by 9 | Viewed by 7687

Abstract

Amphiphilic block-copolymers are known to self-assemble into micelles and vesicles. In this paper, we discuss the multiple options between and beyond these boundaries using amphiphilic AB diblock and ABC triblock copolymers. We adjust the final structure reached by the composition of the mixture, [...] Read more.

Amphiphilic block-copolymers are known to self-assemble into micelles and vesicles. In this paper, we discuss the multiple options between and beyond these boundaries using amphiphilic AB diblock and ABC triblock copolymers. We adjust the final structure reached by the composition of the mixture, by the preparation temperature, and by varying the time-scale of formation. This leads to the formation of vesicles and micelles, but also internal micelles in larger sheets, lamellar vesicles, and closed tubes, thus broadening the amount of self-assembly structures available and deepening our understanding of them. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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13 pages, 1924 KiB

Open AccessArticle

Synthesis and Characterization of Organosoluble, Thermal Stable and Hydrophobic Polyimides Derived from 4-(4-(1-pyrrolidinyl)phenyl)-2,6-bis(4-(4-aminophenoxy)phenyl)pyridine

by Xiaohua Huang^*, Beicai Chen, Mei Mei, Hua Li, Chanjuan Liu^* and Chun Wei

Key Laboratory of New Processing Technology for Nonferrous Metal & Materials, Ministry of Education, and School of Material Science and Engineering, Guilin University of Technology, Guilin 541004, China

Polymers 2017, 9(10), 484; https://doi.org/10.3390/polym9100484 - 3 Oct 2017

Cited by 19 | Viewed by 6852

Abstract

A novel aromatic diamine monomer, 4-(4-(1-pyrrolidinyl)phenyl)-2,6-bis(4-(4-aminophenoxy)phenyl)pyridine (PPAPP) containing pyridine rings, pyrrolidine groups, and ether linkages, was successfully synthesized using 4-hydroxyacetophenone and 1-chloro-4-nitrobenzene as starting materials by three-step reactions, and then used to synthesize a series of polyimides by polycondensation with various aromatic dianhydrides [...] Read more.

A novel aromatic diamine monomer, 4-(4-(1-pyrrolidinyl)phenyl)-2,6-bis(4-(4-aminophenoxy)phenyl)pyridine (PPAPP) containing pyridine rings, pyrrolidine groups, and ether linkages, was successfully synthesized using 4-hydroxyacetophenone and 1-chloro-4-nitrobenzene as starting materials by three-step reactions, and then used to synthesize a series of polyimides by polycondensation with various aromatic dianhydrides via a two-step method. The structure of PPAPP was characterized by NMR, FT-IR, and mass spectrometry analysis methods. These polymers showed good solubility in common organic solvents (e.g., NMP, DMF, DMSO, and DMAc) at room temperature or on heating. Moreover, they presented a high thermal stability with the glass transition temperature (T_gs) exceeding 316 °C, as well as the temperature of 10% weight loss ranged from 552–580 °C with more than 67% residue at 800 °C under nitrogen. Furthermore, they also exhibited excellent hydrophobicity with a contact angle in the range of 85.6°–97.7°, and the results of Wide-Angle X-ray Diffraction (WAXD) indicated that all of the polymers revealed an amorphous structure. Full article

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

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17 pages, 3307 KiB

Open AccessArticle

Controlled Release of Lysozyme from Double-Walled Poly(Lactide-Co-Glycolide) (PLGA) Microspheres

by Rezaul H. Ansary^1,2, Mokhlesur M. Rahman^1,3,*, Nasir Mohamad³, Tengku M. Arrif³, Ahmad Zubaidi A. Latif⁴, Haliza Katas⁵, Wan Sani B. Wan Nik⁶ and Mohamed B. Awang⁷

¹ Faculty of Pharmacy, International Islamic University Malaysia, Kuantan 25200, Malaysia

² Department of Chemistry, University of Rajshahi, Rajshahi 6205, Bangladesh

³ Institute for Community Development & Quality of Life (i-CODE), Universiti Sultan Zainal Abidin, Kuala Nerus 21300, Terengganu, Malaysia

⁴ Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Nerus 21300, Terengganu, Malaysia

⁵ Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Kuala Lumpur 50300, Malaysia

⁶ School of Ocean Engineering, Universiti Malaysia Terengganu, 21300 Kuala Nerus, Terengganu, Malaysia

⁷ Faculty of Pharmacy, Cyberjaya University College of Medical Sciences, Cyberjaya 63000, Malaysia

Polymers 2017, 9(10), 485; https://doi.org/10.3390/polym9100485 - 3 Oct 2017

Cited by 17 | Viewed by 7704

Abstract

Double-walled microspheres based on poly(lactide-co-glycolide) (PLGA) are potential delivery systems for reducing a very high initial burst release of encapsulated protein and peptide drugs. In this study, double-walled microspheres made of glucose core, hydroxyl-terminated poly(lactide-co-glycolide) (Glu-PLGA), and carboxyl-terminated PLGA [...] Read more.

Double-walled microspheres based on poly(lactide-co-glycolide) (PLGA) are potential delivery systems for reducing a very high initial burst release of encapsulated protein and peptide drugs. In this study, double-walled microspheres made of glucose core, hydroxyl-terminated poly(lactide-co-glycolide) (Glu-PLGA), and carboxyl-terminated PLGA were fabricated using a modified water-in-oil-in-oil-in-water (w1/o/o/w2) emulsion solvent evaporation technique for the controlled release of a model protein, lysozyme. Microspheres size, morphology, encapsulation efficiency, lysozyme in vitro release profiles, bioactivity, and structural integrity, were evaluated. Scanning electron microscopy (SEM) images revealed that double-walled microspheres comprising of Glu-PLGA and PLGA with a mass ratio of 1:1 have a spherical shape and smooth surfaces. A statistically significant increase in the encapsulation efficiency (82.52% ± 3.28%) was achieved when 1% (w/v) polyvinyl alcohol (PVA) and 2.5% (w/v) trehalose were incorporated in the internal and external aqueous phase, respectively, during emulsification. Double-walled microspheres prepared together with excipients (PVA and trehalose) showed a better control release of lysozyme. The released lysozyme was fully bioactive, and its structural integrity was slightly affected during microspheres fabrication and in vitro release studies. Therefore, double-walled microspheres made of Glu-PLGA and PLGA together with excipients (PVA and trehalose) provide a controlled and sustained release for lysozyme. Full article

(This article belongs to the Special Issue Emulsion Polymerization)

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12 pages, 4529 KiB

Open AccessArticle

Polymer Blending as a Novel Approach for Tuning the SPR Peaks of Silver Nanoparticles

by Shujahadeen B. Aziz^1,*

, Rebar T. Abdulwahid¹

, Mariwan A. Rasheed², Omed Gh. Abdullah¹

and Hameed M. Ahmed¹

¹ Advanced Polymeric Materials Research Lab., Department of Physics, College of Science, University of Sulaimani, Qlyasan Street, Sulaimani 46001, Kurdistan Region-Iraq

² Development Center for Research and Training (DCRT), University of Human Development, Qrga Street, Sulaimani 46001, Kurdistan Region-Iraq

Polymers 2017, 9(10), 486; https://doi.org/10.3390/polym9100486 - 4 Oct 2017

Cited by 153 | Viewed by 7556

Abstract

In the present work, a novel method is exhibited for tuning the surface plasmon resonance (SPR) peaks of silver nanoparticles based on chitosan-Poly(vinyl alcohol) blend polymer nanocomposites. Silver nanoparticles were synthesized by in situ method through the chitosan host polymer. The absence of [...] Read more.

In the present work, a novel method is exhibited for tuning the surface plasmon resonance (SPR) peaks of silver nanoparticles based on chitosan-Poly(vinyl alcohol) blend polymer nanocomposites. Silver nanoparticles were synthesized by in situ method through the chitosan host polymer. The absence of crystalline peaks of PVA in the blend system indicated the occurrence of miscibility between CS and PVA polymers. The UV–vis spectra of CS:AgNt samples shows SPR bands with weak intensity. Obvious tuning in SPR peaks of silver nanoparticles occurred when different amounts of PVA polymer incorporated to the CS:AgNt system. The appearance of distinguishable crystalline peaks of Ag° nanoparticles at 2θ = 38.6° and 2θ = 44.2° in the blend system reveals the role of polymer blending in the enhancement of SPR peaks of silver nanoparticles. Silver nanoparticles synthesized in this work with enhanced SPR peaks are important in various applications and areas such as optoelectronic devices. The TEM images show dispersed silver nanoparticles. The dielectric constant of PVA is higher than that of chitosan. The result of dielectric constant study validates the Mie model which reveals the fact that the dielectric constant of the surrounding material has a great effect on the SPR peak intensity of nanoparticles. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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16 pages, 5647 KiB

Open AccessArticle

Incorporation of Calcium Containing Mesoporous (MCM-41-Type) Particles in Electrospun PCL Fibers by Using Benign Solvents

by Liliana Liverani¹

, Elena Boccardi¹, Ana Maria Beltrán^2,3

and Aldo R. Boccaccini^1,*

¹ Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany

² Institute de Ciencia de Materiales de Sevilla (ICMS), CSIC-Universidad de Sevilla, Seville 41092, Spain

³ Department of Engineering and Materials Science, University of Seville, Sevilla 41092, Spain

Polymers 2017, 9(10), 487; https://doi.org/10.3390/polym9100487 - 4 Oct 2017

Cited by 30 | Viewed by 7010

Abstract

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2 particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The [...] Read more.

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2 particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The main aims of the present work are both the optimization of the particle synthesis and the fabrication of composite fibers, obtained using benign solvents, suitable as drug delivery systems and scaffolds for soft tissue engineering applications. The optimized synthesis and characterization of calcium-containing MCM-41 particles are reported. Homogeneous bead-free composite electrospun mats were obtained by using acetic acid and formic acid as solvents; neat PCL electrospun mats were used as control. Initially, an optimization of the electrospinning environmental parameters, like relative humidity, was performed. The obtained composite nanofibers were characterized from the morphological, chemical and mechanical points of view, the acellular bioactivity of the composite nanofibers was also investigated. Positive results were obtained in terms of mesoporous particle incorporation in the fibers and no significant differences in terms of average fiber diameter were detected between the neat and composite electrospun fibers. Even if the Ca-containing MCM-41 particles are bioactive, this property is not preserved in the composite fibers. In fact, during the bioactivity assessment, the particles were released confirming the potential application of the composite fibers as a drug delivery system. Preliminary in vitro tests with bone marrow stromal cells were performed to investigate cell adhesion on the fabricated composite mats, the positive obtained results confirmed the suitability of the composite fibers as scaffolds for soft tissue engineering. Full article

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

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11 pages, 3889 KiB

Open AccessArticle

Cluster Formation of Polyphilic Molecules Solvated in a DPPC Bilayer

by Xiang-Yang Guo, Christopher Peschel

, Tobias Watermann, Guido Falk von Rudorff and Daniel Sebastiani^*

Institute of Chemistry, MLU Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle, Germany

Polymers 2017, 9(10), 488; https://doi.org/10.3390/polym9100488 - 6 Oct 2017

Cited by 3 | Viewed by 5405

Abstract

We analyse the initial stages of cluster formation of polyphilic additive molecules which are solvated in a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer. Our polyphilic molecules comprise an aromatic (trans-bilayer) core domain with (out-of-bilayer) glycerol terminations, complemented with a fluorophilic and an alkyl side chain, [...] Read more.

We analyse the initial stages of cluster formation of polyphilic additive molecules which are solvated in a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer. Our polyphilic molecules comprise an aromatic (trans-bilayer) core domain with (out-of-bilayer) glycerol terminations, complemented with a fluorophilic and an alkyl side chain, both of which are confined within the aliphatic segment of the bilayer. Large-scale molecular dynamics simulations (1

μ

s total duration) of a set of six of such polyphilic additives reveal the initial steps towards supramolecular aggregation induced by the specific philicity properties of the molecules. For our intermediate system size of six polyphiles, the transient but recurrent formation of a trimer is observed on a characteristic timescale of about 100 ns. The alkane/perfluoroalkane side chains show a very distinct conformational distribution inside the bilayer thanks to their different philicity, despite their identical anchoring in the trans-bilayer segment of the polyphile. The diffusive mobility of the polyphilic additives is about the same as that of the surrounding lipids, although it crosses both bilayer leaflets and tends to self-associate. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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12 pages, 1662 KiB

Open AccessArticle

Micron-Sized Pored Membranes Based on Polyvinylidene Difluoride Hexafluoropropylene Prepared by Phase Inversion Techniques

by Andreas Hofmann^1,*

, Eva Thißen¹, Matthias Migeot¹, Nicole Bohn², Stefan Dietrich¹

and Thomas Hanemann^1,3

¹ Werkstoffkunde (IAM-WK), Institut für Angewandte Materialien, Karlsruher Institut für Technologie (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

² Keramische Werkstoffe und Technologien (IAM-KWT), Institut für Angewandte Materialien, Karlsruher Institut für Technologie (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

³ Institut für Mikrosystemtechnik, Universität Freiburg, Georges-Köhler-Allee 102, 79110 Freiburg, Germany

Polymers 2017, 9(10), 489; https://doi.org/10.3390/polym9100489 - 6 Oct 2017

Cited by 3 | Viewed by 6275

Abstract

In this study, micron-sized pored membranes, based on the co-polymer polyvinylidene difluoride hexafluoropropylene (PVdF-HFP) were prepared via phase inversion techniques. The aim of the approach was to find less harmful and less toxic solvents to fabricate such films. Therefore, the Hansen solubility approach [...] Read more.

In this study, micron-sized pored membranes, based on the co-polymer polyvinylidene difluoride hexafluoropropylene (PVdF-HFP) were prepared via phase inversion techniques. The aim of the approach was to find less harmful and less toxic solvents to fabricate such films. Therefore, the Hansen solubility approach was used to identify safer and less toxic organic solvents for the phase inversion process, relative to present solvent mixtures, based on acetone, dimethyl formamide, dimethyl acetamide or methanol. With this approach, it was possible to identify cyclopentanone, ethylene glycol and benzyl alcohol as suitable solvents for the membrane preparation process. Physicochemical and mechanical properties were analyzed and compared, which revealed a uniform membrane structure through the cross section. Differences were observed at the top surface, in dependence of both preparation approaches, which are described in detail. Full article

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10 pages, 3599 KiB

Open AccessArticle

Preparation of Isotactic Polypropylene/Exfoliated MoS₂ Nanocomposites via In Situ Intercalative Polymerization

by He-Xin Zhang^1,2

, Xue-Quan Zhang^3,* and Keun-Byoung Yoon^2,*

¹ School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan 243000, China

² Department of Polymer Science and Engineering, Kyungpook National University, Daegu 702-701, Korea

³ CAS Key Laboratory of Synthetic Rubber, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun 130022, China

Polymers 2017, 9(10), 490; https://doi.org/10.3390/polym9100490 - 7 Oct 2017

Cited by 14 | Viewed by 6287

Abstract

In this research, a Ziegler–Natta catalyst intercalated MoS₂ was synthesized through the intercalation of a Grignard reagent into MoS₂ galleries, followed by the anchoring of TiCl4. During propylene polymerization, the intercalated MoS₂ exfoliated in situ to form PP/exfoliated MoS₂ [...] Read more.

In this research, a Ziegler–Natta catalyst intercalated MoS₂ was synthesized through the intercalation of a Grignard reagent into MoS₂ galleries, followed by the anchoring of TiCl4. During propylene polymerization, the intercalated MoS₂ exfoliated in situ to form PP/exfoliated MoS₂ (EMoS₂) nanocomposites. The isotactic index values of the resultant PP/EMoS₂ nanocomposites were as high as 99%, varying from 98.1% to 99.0%. It was found that the incorporation of the EMoS₂ significantly improved the thermal stability and mechanical properties (tensile strength, modulus, and elongation at break) of PP. After introduction of EMoS₂, the maximum increases in T_d_5% and Tdmax were 36.9 and 9.7 °C, respectively, relative to neat PP. After blending with commercial PP, the resultant nanocomposites increase in tensile strength and modulus up to 11.4% and 61.2% after 0.52 wt % EMoS₂ loading. Thus, this work provides a new way to produce high-performance PP. Full article

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

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15 pages, 1916 KiB

Open AccessArticle

Ferrocene-Modified Block Copolymers for the Preparation of Smart Porous Membranes

by Sebastian Schöttner, Rimjhim Hossain, Christian Rüttiger

and Markus Gallei^*

Ernst-Berl Institute for Chemical Engineering and Macromolecular Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 4, D-64287 Darmstadt, Germany

Polymers 2017, 9(10), 491; https://doi.org/10.3390/polym9100491 - 8 Oct 2017

Cited by 28 | Viewed by 8044

Abstract

The design of artificially generated channels featuring distinct remote-switchable functionalities is of critical importance for separation, transport control, and water filtration applications. Here, we focus on the preparation of block copolymers (BCPs) consisting of polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) having molar [...] Read more.

The design of artificially generated channels featuring distinct remote-switchable functionalities is of critical importance for separation, transport control, and water filtration applications. Here, we focus on the preparation of block copolymers (BCPs) consisting of polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) having molar masses in the range of 91 to 124 kg mol⁻¹ with a PHEMA content of 13 to 21 mol %. The BCPs can be conveniently functionalized with redox-active ferrocene moieties by a postmodification protocol for the hydrophilic PHEMA segments. Up to 66 mol % of the hydroxyl functionalities can be efficiently modified with the reversibly redox-responsive units. For the first time, the ferrocene-containing BCPs are shown to form nanoporous integral asymmetric membranes by self-assembly and application of the non-solvent-induced phase separation (SNIPS) process. Open porous structures are evidenced by scanning electron microscopy (SEM) and water flux measurements, while efficient redox-switching capabilities are investigated after chemical oxidation of the ferrocene moieties. As a result, the porous membranes reveal a tremendously increased polarity after oxidation as reflected by contact angle measurements. Additionally, the initial water flux of the ferrocene-containing membranes decreased after oxidizing the ferrocene moieties because of oxidation-induced pore swelling of the membrane. Full article

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

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15 pages, 7778 KiB

Open AccessArticle

Synthesis and Characterization of Multifunctional Two-Component Waterborne Polyurethane Coatings: Fluorescence, Thermostability and Flame Retardancy

by Xuan Yin, Xiaoyu Li and Yunjun Luo^*

School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China

Polymers 2017, 9(10), 492; https://doi.org/10.3390/polym9100492 - 8 Oct 2017

Cited by 28 | Viewed by 6558

Abstract

Fluorescent and flame-retardant two-component waterborne polyurethane coatings were synthesized using 1,5-dihydroxy naphthalene, a halogen-free polyphosphate and a hydrophilic curing agent, and their properties were systematically characterized. The average particle sizes and zeta potential values were below 170 nm and −30 mV. Meanwhile, the [...] Read more.

Fluorescent and flame-retardant two-component waterborne polyurethane coatings were synthesized using 1,5-dihydroxy naphthalene, a halogen-free polyphosphate and a hydrophilic curing agent, and their properties were systematically characterized. The average particle sizes and zeta potential values were below 170 nm and −30 mV. Meanwhile, the multifunctional two-component waterborne polyurethane coatings had strong fluorescence intensities. When comparing with the coatings with 0.5 wt % 1,5-dihydroxy naphthalene, the coatings with 1.0 wt % 1,5-dihydroxy naphthalene had a stronger microphase separation. Interestingly, the thermostability of the multifunctional coatings was remarkably improved through 1.0 wt % 1,5-dihydroxy naphthalene, and besides it belonged to nonflammable materials. Additionally, all of the coating films passed the solvent resistance testing. These samples with different amounts of 1,5-dihydroxy naphthalene are environmental friendly, especially applications that require transparent and fluorescent coatings. Full article

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9 pages, 2801 KiB

Open AccessArticle

Surface Properties of a Novel Poly(vinyl alcohol) Film Prepared by Heterogeneous Saponification of Poly(vinyl acetate) Film

by Seong Baek Yang¹, Sung Hun Yoo¹, Joon Seok Lee², Jong Won Kim^2,* and Jeong Hyun Yeum^1,*

¹ Department of Bio-Fibers and Materials Science, Kyungpook National University, Daegu 41566, Korea

² Department of Textile Engineering & Technology, Yeungnam University, Gyeongsan 38541, Korea

Polymers 2017, 9(10), 493; https://doi.org/10.3390/polym9100493 - 9 Oct 2017

Cited by 23 | Viewed by 9493

Abstract

Almost general poly(vinyl alcohol) (PVA) films were prepared by the processing of a PVA solution. For the first time, a novel poly(vinyl alcohol) (PVA) film was prepared by the saponification of a poly(vinyl acetate) (PVAc) film in a heterogenous medium. Under the same [...] Read more.

Almost general poly(vinyl alcohol) (PVA) films were prepared by the processing of a PVA solution. For the first time, a novel poly(vinyl alcohol) (PVA) film was prepared by the saponification of a poly(vinyl acetate) (PVAc) film in a heterogenous medium. Under the same saponification conditions, the influence of saponification time on the degree of saponification (DS) was studied for the preparation of the saponified PVA film, and it was found that the DS varied with time. Optical microscopy was used to confirm the characteristics and surface morphology of the saponified PVA film, revealing unusual black globules in the film structure. The contact angle of the films was measured to study the surface properties, and the results showed that the saponified PVA film had a higher contact angle than the general PVA film. To confirm the transformation of the PVAc film to the PVA film, ¹H nuclear magnetic resonance spectroscopy, X-ray diffraction measurements, differential scanning calorimetry, and Fourier-transform infrared spectroscopy were employed. Full article

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31 pages, 14133 KiB

Open AccessReview

Block Copolymers: Synthesis, Self-Assembly, and Applications

by Hongbo Feng¹, Xinyi Lu¹, Weiyu Wang², Nam-Goo Kang¹ and Jimmy W. Mays^1,3,*

¹ Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA

² Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA

³ Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA

Polymers 2017, 9(10), 494; https://doi.org/10.3390/polym9100494 - 9 Oct 2017

Cited by 383 | Viewed by 43883

Abstract

Research on block copolymers (BCPs) has played a critical role in the development of polymer chemistry, with numerous pivotal contributions that have advanced our ability to prepare, characterize, theoretically model, and technologically exploit this class of materials in a myriad of ways in [...] Read more.

Research on block copolymers (BCPs) has played a critical role in the development of polymer chemistry, with numerous pivotal contributions that have advanced our ability to prepare, characterize, theoretically model, and technologically exploit this class of materials in a myriad of ways in the fields of chemistry, physics, material sciences, and biological and medical sciences. The breathtaking progress has been driven by the advancement in experimental techniques enabling the synthesis and characterization of a wide range of block copolymers with tailored composition, architectures, and properties. In this review, we briefly discussed the recent progress in BCP synthesis, followed by a discussion of the fundamentals of self-assembly of BCPs along with their applications. Full article

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16 pages, 3526 KiB

Open AccessArticle

Isolation and Characterization of Cellulose from Different Fruit and Vegetable Pomaces

by Monika Szymańska-Chargot^*, Monika Chylińska, Karolina Gdula, Arkadiusz Kozioł and Artur Zdunek

Institute of Agrophysics, Polish Academy of Sciences, Doswiadczalna 4, 20-290 Lublin, Poland

Polymers 2017, 9(10), 495; https://doi.org/10.3390/polym9100495 - 9 Oct 2017

Cited by 244 | Viewed by 21280

Abstract

A new fractionation process was developed to achieve valorization of fruit and vegetable pomaces. The importance of the residues from fruits and vegetables is still growing; therefore; the study presents the novel route of a fractioning process for the conversion of agro-industrial biomasses, [...] Read more.

A new fractionation process was developed to achieve valorization of fruit and vegetable pomaces. The importance of the residues from fruits and vegetables is still growing; therefore; the study presents the novel route of a fractioning process for the conversion of agro-industrial biomasses, such as pomaces, into useful feedstocks with potential application in the fields of fuels, chemicals, and polymers. Hence, the biorefinery process is expected to convert them into various by-products offering a great diversity of low-cost materials. The final product of the process is the cellulose of the biofuel importance. The study presents the novel route of the fractioning process for the conversion of agro-industrial biomasses, such as pomaces, into useful feedstocks with a potential application in the fields of fuels, chemicals, and polymers. Therefore the aim of this paper was to present the novel route of the pomaces fraction and the characterization of residuals. Pomaces from apple, cucumber, carrot, and tomato were treated sequentially with water, acidic solution, alkali solution, and oxidative reagent in order to obtain fractions reach in sugars, pectic polysaccharides, hemicellulose, cellulose, and lignin. Pomaces were characterized by dry matter content, neutral detergent solubles, hemicellulose, cellulose, and lignin. Obtained fractions were characterized by the content of pectins expressed as galacturonic acid equivalent and hemicelluloses expressed as a xyloglucan equivalent. The last fraction and residue was cellulose characterized by crystallinity degree by X-ray diffractometer (XRD), microfibril diameter by atomic force microscope (AFM), and overall morphology by scanning electron microscope (SEM). The hemicelluloses content was similar in all pomaces. Moreover, all the materials were characterized by the high pectins level in extracts evaluated as galacturonic acid content. The lignins content compared with other plant biomasses was on a very low level. The cellulose fraction was the highest in cucumber pomace. The cellulose fraction was characterized by crystallinity degree, microfibril diameter, and overall morphology. Isolated cellulose had a very fine structure with relatively high crystalline index but small crystallites. Full article

(This article belongs to the Special Issue Polysaccharides)

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19 pages, 2778 KiB

Open AccessReview

Systematic Development Strategy for Smart Devices Based on Shape-Memory Polymers

by Andrés Díaz Lantada

Product Development Lab, Mechanical Engineering Department, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal 2, 28006 Madrid, Spain

Polymers 2017, 9(10), 496; https://doi.org/10.3390/polym9100496 - 10 Oct 2017

Cited by 35 | Viewed by 8535

Abstract

Shape-memory polymers are outstanding “smart” materials, which can perform important geometrical changes, when activated by several types of external stimuli, and which can be applied to several emerging engineering fields, from aerospace applications, to the development of biomedical devices. The fact that several [...] Read more.

Shape-memory polymers are outstanding “smart” materials, which can perform important geometrical changes, when activated by several types of external stimuli, and which can be applied to several emerging engineering fields, from aerospace applications, to the development of biomedical devices. The fact that several shape-memory polymers can be structured in an additive way is an especially noteworthy advantage, as the development of advanced actuators with complex geometries for improved performance can be achieved, if adequate design and manufacturing considerations are taken into consideration. Present study presents a review of challenges and good practices, leading to a straightforward methodology (or integration of strategies), for the development of “smart” actuators based on shape-memory polymers. The combination of computer-aided design, computer-aided engineering and additive manufacturing technologies is analyzed and applied to the complete development of interesting shape-memory polymer-based actuators. Aspects such as geometrical design and optimization, development of the activation system, selection of the adequate materials and related manufacturing technologies, training of the shape-memory effect, final integration and testing are considered, as key processes of the methodology. Current trends, including the use of low-cost 3D and 4D printing, and main challenges, including process eco-efficiency and biocompatibility, are also discussed and their impact on the proposed methodology is considered. Full article

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

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24 pages, 13360 KiB

Open AccessArticle

Facile Synthesis of Electroactive and Electrochromic Triptycene Poly(ether-imide)s Containing Triarylamine Units via Oxidative Electro-Coupling

by Sheng-Huei Hsiao^*

and Yu-Chuan Liao

Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Sec. 3, Chunghsiao East Rd., Taipei 10608, Taiwan

Polymers 2017, 9(10), 497; https://doi.org/10.3390/polym9100497 - 10 Oct 2017

Cited by 14 | Viewed by 7599

Abstract

Two bisimide compounds, TPA–TPDI and NPC–TPDI, consisting of a triptycene core and two triphenylamine (TPA) or N-phenylcarbazole (NPC) end groups were successfully synthesized by the condensation reactions from 1,4-bis(3,4-dicarboxyphenoxy)triptycene dianhydride with 4-aminotriphenylamine and N-(4-aminophenyl)carbazole, respectively. These two monomers could polymerize electrochemically via the [...] Read more.

Two bisimide compounds, TPA–TPDI and NPC–TPDI, consisting of a triptycene core and two triphenylamine (TPA) or N-phenylcarbazole (NPC) end groups were successfully synthesized by the condensation reactions from 1,4-bis(3,4-dicarboxyphenoxy)triptycene dianhydride with 4-aminotriphenylamine and N-(4-aminophenyl)carbazole, respectively. These two monomers could polymerize electrochemically via the oxidative coupling reactions of triarylamine units. The electrochemical and spectroelectrochemical properties of the electro-generated triptycene poly(ether-imide)s (TPA–TPPI and NPC–TPPI) were studied. Both polymers have two colored oxidation states, and TPA–TPPI showed better electrochromic performance than NPC–TPPI. Full article

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

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11 pages, 1173 KiB

Open AccessArticle

Microwave-Assisted Synthesis of Nanoporous Aluminum-Based Coordination Polymers as Catalysts for Selective Sulfoxidation Reaction

by Madhan Vinu

, Wei-Cheng Lin, Duraisamy Senthil Raja, Jeng-Liang Han^* and Chia-Her Lin^*

Department of Chemistry, Chung Yuan Christian University, Chung Li, Taoyuan 32023, Taiwan

Polymers 2017, 9(10), 498; https://doi.org/10.3390/polym9100498 - 11 Oct 2017

Cited by 33 | Viewed by 8352

Abstract

A series of aluminum-based coordination polymers or metal–organic frameworks (Al–MOFs), i.e., DUT-4, DUT-5, MIL-53, NH₂-MIL-53, and MIL-100, have been facile prepared by microwave (MW)-assisted reactions and used as catalysts for selective sulfoxidation reactions. The MW-assisted synthesis drastically reduced the reaction time [...] Read more.

A series of aluminum-based coordination polymers or metal–organic frameworks (Al–MOFs), i.e., DUT-4, DUT-5, MIL-53, NH₂-MIL-53, and MIL-100, have been facile prepared by microwave (MW)-assisted reactions and used as catalysts for selective sulfoxidation reactions. The MW-assisted synthesis drastically reduced the reaction time from few days to hours. The prepared MOFs have smaller and uniform particle sizes and better yield compared to conventional hydrothermal method. Furthermore, the Al–MOFs have been successfully demonstrated as catalysts in oxidation reaction of methyl phenyl sulfide with H₂O₂ as oxidant, even under mild conditions, with more than 95% conversion. Full article

(This article belongs to the Special Issue Coordination Polymer)

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24 pages, 4275 KiB

Open AccessReview

Polymer Nanocomposites via Click Chemistry Reactions

by Mehmet Arslan^* and Mehmet Atilla Tasdelen^*

Department of Polymer Engineering, Faculty of Engineering, Yalova University, 77200 Yalova, Turkey

Polymers 2017, 9(10), 499; https://doi.org/10.3390/polym9100499 - 11 Oct 2017

Cited by 49 | Viewed by 14627

Abstract

The emerging areas of polymer nanocomposites, as some are already in use in industrial applications and daily commodities, have the potential of offering new technologies with all manner of prominent capabilities. The incorporation of nanomaterials into polymeric matrix provides significant improvements, such as [...] Read more.

The emerging areas of polymer nanocomposites, as some are already in use in industrial applications and daily commodities, have the potential of offering new technologies with all manner of prominent capabilities. The incorporation of nanomaterials into polymeric matrix provides significant improvements, such as higher mechanical, thermal or electrical properties. In these materials, interface/interphase of components play a crucial role bringing additional features on the resulting nanocomposites. Among the various preparation strategies of such materials, an appealing strategy relies on the use of click chemistry concept as a multi-purpose toolbox for both fabrication and modulation of the material characteristics. This review aims to deliver new insights to the researchers of the field by noticing effective click chemistry-based methodologies on the preparation of polymer nanocomposites and their key applications such as optic, biomedical, coatings and sensor. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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18 pages, 2060 KiB

Open AccessReview

Synthesis and Application of Aurophilic Poly(Cysteine) and Poly(Cysteine)-Containing Copolymers

by David Ulkoski and Carmen Scholz^*

Department of Chemistry, University of Alabama, 301 Sparkman Dr., Huntsville, AL 35899, USA

Polymers 2017, 9(10), 500; https://doi.org/10.3390/polym9100500 - 11 Oct 2017

Cited by 13 | Viewed by 9852

Abstract

The redox capacity, as well as the aurophilicity of the terminal thiol side groups, in poly(Cysteine) lend a unique characteristic to this poly(amino acid) or polypeptide. There are two major application fields for this polymer: (i) biomedical applications in drug delivery and surface [...] Read more.

The redox capacity, as well as the aurophilicity of the terminal thiol side groups, in poly(Cysteine) lend a unique characteristic to this poly(amino acid) or polypeptide. There are two major application fields for this polymer: (i) biomedical applications in drug delivery and surface modification of biomedical devices and (ii) as coating for electrodes to enhance their electrochemical sensitivity. The intended application determines the synthetic route for p(Cysteine). Polymers to be used in biomedical applications are typically polymerized from the cysteine N-carboxyanhydride by a ring-opening polymerization, where the thiol group needs to be protected during the polymerization. Advances in this methodology have led to conditions under which the polymerization progresses as living polymerization, which allows for a strict control of the molecular architecture, molecular weight and polydispersity and the formation of block copolymers, which eventually could display polyphilic properties. Poly(Cysteine) used as electrode coating is typically polymerized onto the electrode by cyclic voltammetry, which actually produces a continuous, pinhole-free film on the electrode via the formation of covalent bonds between the amino group of Cysteine and the carbon of the electrode. This resulting coating is chemically very different from the well-defined poly(Cysteine) obtained by ring-opening polymerizations. Based on the structure of cysteine a significant degree of cross-linking within the coating deposited by cyclic voltammetry can be assumed. This manuscript provides a detailed discussion of the ring-opening polymerization of cysteine, a brief consideration of the role of glutathione, a key cysteine-containing tripeptide, and examples for the utilization of poly(Cysteine) and poly(Cysteine)-containing copolymers, in both, the biomedical as well as electrochemical realm. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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16 pages, 559 KiB

Open AccessArticle

Influence of Polymer Relaxation Time on the Electrospinning Process: Numerical Investigation

by Siddharth Gadkari^1,2

¹ Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3168, Australia

² Department of Chemical Engineering, Indian Institute of Technology–Bombay, Mumbai 400076, India

Polymers 2017, 9(10), 501; https://doi.org/10.3390/polym9100501 - 12 Oct 2017

Cited by 26 | Viewed by 6754

Abstract

“Electrospinnability”, or the ease with which a solution can be used to obtain bead-free uniform fibers, depends on a large number of parameters, including solution properties, process parameters and ambient conditions. In this study, the effect of the polymer relaxation time on electrospinning [...] Read more.

“Electrospinnability”, or the ease with which a solution can be used to obtain bead-free uniform fibers, depends on a large number of parameters, including solution properties, process parameters and ambient conditions. In this study, the effect of the polymer relaxation time on electrospinning of dilute polymer solutions is investigated numerically. It is shown that elastic stresses (ES) increase exponentially with the Deborah number (

D e

). For each polymer concentration there exists a critical

D e

below which the ES are insufficient to overcome capillary stresses (CS) and lead to the formation of beaded fibers. However, above the critical

D e

, there is a higher probability of the ES overcoming the CS and leading to the formation of uniform fibers. This analysis suggests the possibility of improved electrospinnability even with dilute polymer solutions, provided the relaxation time is sufficiently large. It is also found that changes in the drag coefficient due to change in the polymer conformation and self-concentration of polymer molecules would become significant for the electrospinning of polymer solutions with a longer relaxation time and high conductivity. Full article

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19 pages, 5523 KiB

Open AccessArticle

Fabrication of Al₂O₃ Nano-Structure Functional Film on a Cellulose Insulation Polymer Surface and Its Space Charge Suppression Effect

by Jian Hao^1,*

, Yanqing Li¹, Ruijin Liao¹, Guoyong Liu², Qiang Liao³ and Chao Tang⁴

¹ The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China

² College of Material Science and Engineering, Chongqing University, Chongqing 400044, China

³ College of Power Engineering, Chongqing University, Chongqing 400044, China

⁴ College of Engineering and Technology, Southwest University, Chongqing 400715, China

Polymers 2017, 9(10), 502; https://doi.org/10.3390/polym9100502 - 12 Oct 2017

Cited by 37 | Viewed by 7036

Abstract

Cellulose insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in [...] Read more.

Cellulose insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a cellulose insulation pressboard surface using reactive radio frequency (RF) magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al₂O₃ film with amorphous phase was successfully fabricated onto the fibre surface. The cellulose insulation pressboard surface sputtered by Al₂O₃ film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (<10³ Hz) region. The oil-impregnated sputtered pressboard presents an apparent space-charge suppression effect. Compared with the pressboard sputtered with Al₂O₃ film for 90 min, the pressboard sputtered with Al₂O₃ film for 60 min had a better space charge suppression effect. Ultra-small Al₂O₃ particles (<10 nm) grew on the surface of the larger nanoparticles. The nano-structured Al₂O₃ film sputtered on the fibre surface could act as a functional barrier layer for suppression of the charge injection and accumulation. This study offers a new perspective in favour of the application of insulation pressboard with a nano-structured function surface against space charge injection/accumulation in HVDC equipment. Full article

(This article belongs to the Collection Polysaccharides)

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19 pages, 3812 KiB

Open AccessArticle

Supramolecular Interactions Induce Unexpectedly Strong Emissions from Triphenylamine-Functionalized Polytyrosine Blended with Poly(4-vinylpyridine)

by Yu-Ru Jheng¹, Mohamed Gamal Mohamed¹

and Shiao-Wei Kuo^1,2,3,*

¹ Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan

² Ningbo Institute of Material Technology and Engineering, Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Chinese Academy of Science, Zhongguan West Road 1219, Ningbo 315201, China

³ Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80424, Taiwan

Polymers 2017, 9(10), 503; https://doi.org/10.3390/polym9100503 - 12 Oct 2017

Cited by 14 | Viewed by 6855

Abstract

In this study, we synthesized a triphenylamine-functionalized polytyrosine (PTyr-TPA) through living ring opening polymerization with 4,4′-diamino-4″-methoxytriphenylamine (TPA-NH₂) as an initiator, and used Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy to confirm the chemical structure. Photoluminescence spectroscopy revealed the photophysical [...] Read more.

In this study, we synthesized a triphenylamine-functionalized polytyrosine (PTyr-TPA) through living ring opening polymerization with 4,4′-diamino-4″-methoxytriphenylamine (TPA-NH₂) as an initiator, and used Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy to confirm the chemical structure. Photoluminescence spectroscopy revealed the photophysical properties of TPA-NH₂ and PTyr-TPA and suggested that TPA-NH₂ exhibited aggregation-caused quenching; in contrast, attaching the initiator to the rigid rod conformation of the PTyr segments caused PTyr-TPA to display aggregation-induced emission behavior. Differential scanning calorimetry revealed single glass transition temperatures for miscible PTyr-TPA/P4VP blends, the result of intermolecular hydrogen bonding between the pyridine units of P4VP and the phenolic OH units of PTyr-TPA, as confirmed through FTIR spectroscopic analyses. Furthermore, the chain behavior of PTyr-TPA transformed from a β-sheet conformation to random coils after blending with P4VP, as determined using wide-angle X-ray diffraction. These findings suggest that the decreased emission intensity of PTyr-TPA resulted from release of the restricted intramolecular rotation of the triphenylamine moiety in the polypeptide center. Full article

(This article belongs to the Special Issue Smart Polymers)

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18 pages, 4807 KiB

Open AccessArticle

Interfacial Hydrogen Bonds and Their Influence Mechanism on Increasing the Thermal Stability of Nano-SiO₂-Modified Meta-Aramid Fibres

by Chao Tang^1,2,*, Xu Li¹, Zhiwei Li¹ and Jian Hao³

¹ College of Engineering and Technology, Southwest University, Chongqing 400715, China

² School of Electronics and Computer Science, University of Southampton, Southampton SO171BJ, UK

³ Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China

Polymers 2017, 9(10), 504; https://doi.org/10.3390/polym9100504 - 12 Oct 2017

Cited by 80 | Viewed by 9306

Abstract

For further analysis of the effect of nano-doping on the properties of high polymers and research into the mechanism behind modified interfacial hydrogen bonds, a study on the formation probability of nano-SiO₂/meta-aramid fibre interfacial hydrogen bonds and the strengthening mechanism behind [...] Read more.

For further analysis of the effect of nano-doping on the properties of high polymers and research into the mechanism behind modified interfacial hydrogen bonds, a study on the formation probability of nano-SiO₂/meta-aramid fibre interfacial hydrogen bonds and the strengthening mechanism behind interfacial hydrogen bonds on the thermal stability of meta-aramid fibres using molecular dynamics is performed in this paper. First, the pure meta-aramid fibre and nano-SiO₂/meta-aramid fibre mixed models with nanoparticle radiuses of 3, 5, 7 and 9 Å (1 Å = 10⁻¹ nm) are built, and then the optimization process and dynamics simulation of the models are conducted. The dynamics simulation results indicate that the number of hydrogen bonds increase due to the doping by nano-SiO₂ and that the number of interfacial hydrogen bonds increases with the nanoparticle radius. By analysing the hydrogen bond formation probability of all the atom pairs in the mixed model with pair correlation functions (PCFs), it can be observed that the hydrogen bond formation probability between the oxygen atom and hydrogen atom on the nanoparticle surface is the greatest. An effective way to increase the number of interfacial hydrogen bonds in nano-SiO₂ and meta-aramid fibres is to increase the number of hydrogen atoms on the nano-silica surface and oxygen atoms in the meta-aramid fibre. By using the radial distribution function (RDF), the conclusion can be further drawn that the hydrogen bond formation probability is at a maximum when the atomic distance is 2.7–2.8 Å; therefore, increasing the number of atoms within this range can significantly increase the formation probability of hydrogen bonds. According to the results of chain movement, the existence of interfacial hydrogen bonds effectively limits the free movement of the molecular chains of meta-aramid fibres and enhances the thermal stability of meta-aramid fibres. The existence of interfacial hydrogen bonds is one of the important reasons for formation of the stable interface structure between nanoparticles and meta-aramid fibres. In addition, a nanoparticle with a small radius improves the interfacial hydrogen bond energy density and interfacial interaction energy density, enhancing the stability of the mixed model interface. Full article

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17 pages, 10276 KiB

Open AccessArticle

Correlating PSf Support Physicochemical Properties with the Formation of Piperazine-Based Polyamide and Evaluating the Resultant Nanofiltration Membrane Performance

by Micah Belle Marie Yap Ang¹, Victor Jr. Lau², Yan-Li Ji^1,3,*, Shu-Hsien Huang^1,4,*, Quan-Fu An⁵, Alvin R. Caparanga²

, Hui-An Tsai¹, Wei-Song Hung¹, Chien-Chieh Hu¹, Kueir-Rarn Lee^1,* and Juin-Yih Lai^1,6

¹ R&D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan University, Taoyuan 32023, Taiwan

² School of Chemical Engineering and Chemistry, Mapúa University, Manila 1002, Philippines

³ Center for Membrane and Water Science & Technology, Ocean College, Zhejiang University of Technology, Hangzhou 310014, China

⁴ Department of Chemical and Materials Engineering, National Ilan University, Yilan 26047, Taiwan

⁵ Beijing Key Laboratory for Green Catalysis and Separation, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China

⁶ Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan

Polymers 2017, 9(10), 505; https://doi.org/10.3390/polym9100505 - 13 Oct 2017

Cited by 48 | Viewed by 8191

Abstract

Membrane support properties influence the performance of thin-film composite nanofiltration membranes. We fabricated several polysulfone (PSf) supports. The physicochemical properties of PSf were altered by adding polyethylene glycol (PEG) of varying molecular weights (200–35,000 g/mol). This alteration facilitated the formation of a thin [...] Read more.

Membrane support properties influence the performance of thin-film composite nanofiltration membranes. We fabricated several polysulfone (PSf) supports. The physicochemical properties of PSf were altered by adding polyethylene glycol (PEG) of varying molecular weights (200–35,000 g/mol). This alteration facilitated the formation of a thin polyamide layer on the PSf surface during the interfacial polymerization reaction involving an aqueous solution of piperazine containing 4-aminobenzoic acid and an organic solution of trimesoyl chloride. Attenuated total reflectance-Fourier transform infrared validated the presence of PEG in the membrane support. Scanning electron microscopy and atomic force microscopy illustrated that the thin-film polyamide layer morphology transformed from a rough to a smooth surface. A cross-flow filtration test indicated that a thin-film composite polyamide membrane comprising a PSf support (TFC-PEG20k) with a low surface porosity, small pore size, and suitable hydrophilicity delivered the highest water flux and separation efficiency (J = 81.1 ± 6.4 L·m⁻²·h⁻¹, R_Na2SO4 = 91.1% ± 1.8%, and R_NaCl = 35.7% ± 3.1% at 0.60 MPa). This membrane had a molecular weight cutoff of 292 g/mol and also a high rejection for negatively charged dyes. Therefore, a PSf support exhibiting suitable physicochemical properties endowed a thin-film composite polyamide membrane with high performance. Full article

(This article belongs to the Special Issue Polymeric Membranes)

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29 pages, 7042 KiB

Open AccessReview

Synthesis, Morphologies and Building Applications of Nanostructured Polymers

by Yong Lu¹, Kwok Wei Shah^1,*

and Jianwei Xu^2,*

¹ School of Design and Environment, National University of Singapore, 4 Architecture Drive, Singapore 117566, Singapore

² Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore

Polymers 2017, 9(10), 506; https://doi.org/10.3390/polym9100506 - 13 Oct 2017

Cited by 35 | Viewed by 9223

Abstract

Nanostructured polymers (NSPs) are polymeric materials in the size of nanoscale, normally consisting of nanoparticles, nanofibers, nanowires, nanospheres and other morphologies. Polymer nanoparticles (PNPs) can be fabricated either by physical methods (i.e., solvent evaporation, nanoprecipitation, salting out) or by direct nanosynthesis, using micro- [...] Read more.

Nanostructured polymers (NSPs) are polymeric materials in the size of nanoscale, normally consisting of nanoparticles, nanofibers, nanowires, nanospheres and other morphologies. Polymer nanoparticles (PNPs) can be fabricated either by physical methods (i.e., solvent evaporation, nanoprecipitation, salting out) or by direct nanosynthesis, using micro- or nanoemulsions with nanoreactor compartments to perform polymerization. Polymer nanofibers (PNFs) can be produced via various techniques and the most commonly used approach is electrospinning, whereby a charged solution of a polymer when exposed to an opposite high electric field is pulled into long thin nanofibers. NSPs in general exhibit enhanced properties such as excellent structural and mechanical properties, making them promising candidates for some particular building applications. A variety of PNFs have been developed and used for noise and air pollution filtration. Moreover, PNFs can also be fabricated with phase change materials which are usually employed for thermal energy storage in construction industry. In this review, we will summarize the morphologies and nanosynthesis methods of NSPs, in particular, PNPs and PNFs. In addition, representative NSPs mainly used in construction are introduced for building applications. Full article

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

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12 pages, 2174 KiB

Open AccessArticle

Spontaneous Formation of Fractal Aggregates of Au Nanoparticles in Epoxy-Siloxane Films and Their Application as Substrates for NIR Surface Enhanced Raman Spectroscopy

by Dinesh K. Basker and Kalaichelvi Saravanamuttu^*

Department of Chemistry and Chemical Biology, McMaster University, 1280 Main St. West, Hamilton, ON L8S 4M1, Canada

Polymers 2017, 9(10), 507; https://doi.org/10.3390/polym9100507 - 13 Oct 2017

Cited by 3 | Viewed by 5681

Abstract

We present a facile, inexpensive route to free-standing, thermo-mechanically robust and flexible epoxy-siloxane substrates embedded with fractal aggregates of Au nanoparticles, and demonstrate their efficiency as substrates for surface enhanced Raman spectroscopy (SERS) at NIR wavelengths. The metallodielectric films are prepared by generating [...] Read more.

We present a facile, inexpensive route to free-standing, thermo-mechanically robust and flexible epoxy-siloxane substrates embedded with fractal aggregates of Au nanoparticles, and demonstrate their efficiency as substrates for surface enhanced Raman spectroscopy (SERS) at NIR wavelengths. The metallodielectric films are prepared by generating Au nanoparticles through the in-situ reduction of gold (III) chloride trihydrate in epoxypropoxypropyl terminated polydimethyl siloxane (EDMS). The metal nanoparticles spontaneously aggregate into fractal structures in the colloid, which could then be drop-cast onto a substrate. Subsequent UV-initiated cationic polymerization of epoxide moieties in EDMS transforms the fluid colloid into a thin, free-standing film, which contains a dense distribution of fractal aggregates of Au nanoparticles. We used electron and optical microscopy as well as UV–Vis–NIR spectrometry to monitor the evolution of nanoparticles and to optically and structurally characterize the resulting films. Raman spectroscopy of the chromophore Eosin Y adsorbed onto the metallodielectric films showed that they are excellent SERS substrates at NIR excitation with an enhancement factor of ~9.3 × 10³. Full article

(This article belongs to the Special Issue Photo-Responsive Polymers)

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11 pages, 5393 KiB

Open AccessArticle

Evolution of Surface Nanopores in Pressurised Gyrospun Polymeric Microfibers

by U. Eranka Illangakoon^*, Suntharavathanan Mahalingam, Rupy K. Matharu

and Mohan Edirisinghe

Department of Mechanical Engineering, University College London, London WC1E 7JE, UK

Polymers 2017, 9(10), 508; https://doi.org/10.3390/polym9100508 - 13 Oct 2017

Cited by 26 | Viewed by 5874

Abstract

The selection of a solvent or solvent system and the ensuing polymer–solvent interactions are crucial factors affecting the preparation of fibers with multiple morphologies. A range of poly(methylmethacrylate) fibers were prepared by pressurised gyration using acetone, chloroform, N,N-dimethylformamide (DMF), ethyl acetate and [...] Read more.

The selection of a solvent or solvent system and the ensuing polymer–solvent interactions are crucial factors affecting the preparation of fibers with multiple morphologies. A range of poly(methylmethacrylate) fibers were prepared by pressurised gyration using acetone, chloroform, N,N-dimethylformamide (DMF), ethyl acetate and dichloromethane as solvents. It was found that microscale fibers with surface nanopores were formed when using chloroform, ethyl acetate and dichloromethane and poreless fibers were formed when using acetone and DMF as the solvent. These observations are explained on the basis of the physical properties of the solvents and mechanisms of pore formation. The formation of porous fibers is caused by many solvent properties such as volatility, solubility parameters, vapour pressure and surface tension. Cross-sectional images show that the nanopores are only on the surface of the fibers and they were not inter-connected. Further, the results show that fibers with desired nanopores (40–400 nm) can be prepared by carefully selecting the solvent and applied pressure in the gyration process. Full article

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15 pages, 2457 KiB

Open AccessArticle

The Effect of Heat Transfer and Polymer Concentration on Non-Newtonian Fluid from Pore-Scale Simulation of Rock X-ray Micro-CT

by Moussa Tembely^*

, Ali M. AlSumaiti, Mohamed S. Jouini

and Khurshed Rahimov

Petroleum Institute, Khalifa University of Science and Technology, P.O. Box 2533, Abu Dhabi, UAE

Polymers 2017, 9(10), 509; https://doi.org/10.3390/polym9100509 - 13 Oct 2017

Cited by 20 | Viewed by 6885

Abstract

Most of the pore-scale imaging and simulations of non-Newtonian fluid are based on the simplifying geometry of network modeling and overlook the fluid rheology and heat transfer. In the present paper, we developed a non-isothermal and non-Newtonian numerical model of the flow properties [...] Read more.

Most of the pore-scale imaging and simulations of non-Newtonian fluid are based on the simplifying geometry of network modeling and overlook the fluid rheology and heat transfer. In the present paper, we developed a non-isothermal and non-Newtonian numerical model of the flow properties at pore-scale by simulation of the 3D micro-CT images using a Finite Volume Method (FVM). The numerical model is based on the resolution of the momentum and energy conservation equations. Owing to an adaptive mesh generation technique and appropriate boundary conditions, rock permeability and mobility are accurately computed. A temperature and concentration-dependent power-law viscosity model in line with the experimental measurement of the fluid rheology is adopted. The model is first applied at isothermal condition to 2 benchmark samples, namely Fontainebleau sandstone and Grosmont carbonate, and is found to be in good agreement with the Lattice Boltzmann method (LBM). Finally, at non-isothermal conditions, an effective mobility is introduced that enables to perform a numerical sensitivity study to fluid rheology, heat transfer, and operating conditions. While the mobility seems to evolve linearly with polymer concentration in agreement with a derived theoretical model, the effect of the temperature seems negligible by comparison. However, a sharp contrast is found between carbonate and sandstone under the effect of a constant temperature gradient. Besides concerning the flow index and consistency factor, a master curve is derived when normalizing the mobility for both the carbonate and the sandstone. Full article

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11 pages, 6570 KiB

Open AccessArticle

Facile Synthesis of Polyaniline Nanotubes with Square Capillary Using Urea as Template

by Shuhua Pang^1,†, Weiliang Chen^1,†, Zhewei Yang^1,†, Zheng Liu^1,2,†, Xin Fan^1,* and Dong Fang^3,*

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

² BengBu Center of Product Quality Supervising and Inspection, BengBu 233000, China

³ Key Lab of Green Processing and Functional Textiles of New Textile Materials, Ministry of Education, College of Material Science and Engineering, Wuhan Textile University, Wuhan 430700, China

^† These authors contributed equally to this work.

Polymers 2017, 9(10), 510; https://doi.org/10.3390/polym9100510 - 14 Oct 2017

Cited by 24 | Viewed by 6657

Abstract

Polyaniline nanotubes were successfully synthesized by a facile in situ chemical oxidative polymerization method using urea as soft template. When the urea/aniline molar ratio is 3:1, the as-prepared nanotubular polyaniline (PANI-3) shows regular and uniform square capillaries, which provides a high electrode/electrolyte contact, [...] Read more.

Polyaniline nanotubes were successfully synthesized by a facile in situ chemical oxidative polymerization method using urea as soft template. When the urea/aniline molar ratio is 3:1, the as-prepared nanotubular polyaniline (PANI-3) shows regular and uniform square capillaries, which provides a high electrode/electrolyte contact, easy ion diffusion and enhanced electroactive regions during the electrochemical process, leading to weak internal resistance and improved electrochemical performance. The PANI-3 sample exhibits a high specific capacitance of 405 F/g at current density of 0.2 A/g, and PANI only has a specific capacitance of 263 F/g. At current density of 1 A/g, the capacitance of PANI-3 is still 263 F/g (64.9% of the capacitance at 0.2 A/g). Such a PANI-3 nanotube, with regular and uniform capillary, is a promising electrode material for high-performance supercapacitors. Full article

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17 pages, 7329 KiB

Open AccessArticle

Synthesis and Electrochromism of Highly Organosoluble Polyamides and Polyimides with Bulky Trityl-Substituted Triphenylamine Units

by Sheng-Huei Hsiao^1,*

, Wei-Kai Liao^1,2 and Guey-Sheng Liou^2,*

¹ Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Sec. 3, Chunghsiao East Rd., Taipei 10608, Taiwan

² Institute of Polymer Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan

Polymers 2017, 9(10), 511; https://doi.org/10.3390/polym9100511 - 14 Oct 2017

Cited by 36 | Viewed by 8395

Abstract

Two series of polyamides and polyimides containing bulky trityl-substituted triphenylamine units were synthesized from condensation reactions of 4,4′-diamino-4′′-trityltriphenylamine with various dicarboxylic acids and tetracarboxylic dianhydrides, respectively. The polymers showed good solubility and film-forming ability. Flexible or robust films could be readily obtained via [...] Read more.

Two series of polyamides and polyimides containing bulky trityl-substituted triphenylamine units were synthesized from condensation reactions of 4,4′-diamino-4′′-trityltriphenylamine with various dicarboxylic acids and tetracarboxylic dianhydrides, respectively. The polymers showed good solubility and film-forming ability. Flexible or robust films could be readily obtained via solution-casting. The use of aliphatic diacid or dianhydride reduces interchain charge transfer complexing and leads to colorless polyamide and polyimide films. These polymers showed glass-transition temperatures in the range of 206–336 °C. Cyclic voltammograms of the polyamide and polyimide films displayed reversible electrochemical oxidation processes in the range of 0–1.0 or 0–1.3 V. Upon oxidation, the color of polymer films changes from colorless to blue-green or blue. As compared to the polyimide counterparts, the polyamides showed lower oxidation potentials and thus a higher electrochromic stability and coloration efficiency. Simple electrochromic devices were also fabricated as a preliminary investigation for electrochromic applications of the prepared polymers. Full article

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

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14 pages, 4148 KiB

Open AccessArticle

Conjugated Polymers Containing BODIPY and Fluorene Units for Sensitive Detection of CN⁻ Ions: Site-Selective Synthesis, Photo-Physical and Electrochemical Properties

by Tian He^†, Danting Tang^†, Cuiling Lin, Xi Shen, Chenjie Lu, Luonan Xu, Zhengye Gu, Zheng Xu, Huayu Qiu, Qian Zhang^* and Shouchun Yin^*

¹ College of Material Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036, China

^† These authors contributed equally to this work.

Polymers 2017, 9(10), 512; https://doi.org/10.3390/polym9100512 - 14 Oct 2017

Cited by 22 | Viewed by 7388

Abstract

Conjugated polymers containing distinct molecular units are expected to be very interesting because of their unique properties endowed by these units and the formed conjugated polymers. Herein, four new conjugated copolymers based on fluorene and 4,4’-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) have been designed and [...] Read more.

Conjugated polymers containing distinct molecular units are expected to be very interesting because of their unique properties endowed by these units and the formed conjugated polymers. Herein, four new conjugated copolymers based on fluorene and 4,4’-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) have been designed and synthesized via Sonogashira polymerization. The fluorene unit was attached to the 3,5- or 2,6-positions of BODIPY by ethynylenes or p-diacetylenebenzene. The obtained polymers show good thermal stability and broad absorption in the wavelength range from 300 to 750 nm. The effects of site-selective copolymerization and conjugation length along the polymer backbone on the optoelectronic and electrochemical properties of these copolymers were systematically studied by UV-Vis spectroscopy, photoluminescence (PL) and cyclic voltammetry. Besides, it is found that the BODIPY-based copolymers exhibit selectively sensitive responses to cyanide anions, resulting in obvious change of UV-Vis absorption spectra and significant fluorescence quenching of the polymers among various common anions. Full article

(This article belongs to the Special Issue Conjugated Polymers 2016)

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14 pages, 5495 KiB

Open AccessArticle

A Low-Cost, Formaldehyde-Free and High Flame Retardancy Wood Adhesive from Inorganic Adhesives: Properties and Performance

by Shicun Jin^1,2,3, Kuang Li^1,2,3

, Jianzhang Li^1,2,3,* and Hui Chen^1,2,3,*

¹ Key Laboratory of Wood Materials Science and Utilization (Beijing Forestry University), Ministry of Education, Beijing 100083, China

² Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China

³ College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China

Polymers 2017, 9(10), 513; https://doi.org/10.3390/polym9100513 - 16 Oct 2017

Cited by 49 | Viewed by 8417

Abstract

Wood composites used in indoor living environments often pose formaldehyde emission and fire hazard problems. In this study, magnesium oxychloride cement-based (MOC) inorganic adhesives are presented as an effective and sustainable binder for plywood applications. The phase composition, microstructure, and thermal stability of [...] Read more.

Wood composites used in indoor living environments often pose formaldehyde emission and fire hazard problems. In this study, magnesium oxychloride cement-based (MOC) inorganic adhesives are presented as an effective and sustainable binder for plywood applications. The phase composition, microstructure, and thermal stability of the adhesives prepared with different ratios of MgO/MgCl₂ were investigated. In addition, the dry and wet shear strength and the combustion behavior of the plywood were also examined. The results indicated that the limiting oxygen index (LOI) values of the plywood bonded by the MOC adhesives were higher than those of the plywood bonded by urea-formaldehyde resin. The active MgO/MgCl₂ molar ratio of 7 was the optimal ratio for the dry and wet shear strength of the plywood with values of 1.02 and 0.88 MPa, respectively, which meet the interior use panel (Type II plywood) requirements. These improvements were ascribed to the increasing ratio of MgO/MgCl₂ that facilitated the formation of an excellent microstructure. Meanwhile, the continuous hydration phase strengthened the interaction between the MOC adhesive and the wood. With these improved properties, MOC adhesive is expected to be widely used for industrial applications in plywood fabrication. Full article

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11 pages, 981 KiB

Open AccessArticle

Characterization and Performance of Soy-Based Adhesives Cured with Epoxy Resin

by Nairong Chen^*

, Peitao Zheng, Qinzhi Zeng, Qiaojia Lin^* and Jiuping Rao^*

College of Materials Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China

Polymers 2017, 9(10), 514; https://doi.org/10.3390/polym9100514 - 16 Oct 2017

Cited by 61 | Viewed by 6605

Abstract

Soy-based adhesives have attracted much attention recently because they are environmentally safe, low cost, and readily available. To improve the gluability and water resistance of soy-based adhesives, we prepared an enzyme-treated soy-based adhesive modified with an epoxy resin. We investigated the wet shear [...] Read more.

Soy-based adhesives have attracted much attention recently because they are environmentally safe, low cost, and readily available. To improve the gluability and water resistance of soy-based adhesives, we prepared an enzyme-treated soy-based adhesive modified with an epoxy resin. We investigated the wet shear strength of plywood bonded with the modified adhesive using the boiling-water test. Fourier transformed infrared spectroscopy (FTIR) and ¹H nuclear magnetic resonance analysis were used to characterize the reaction between epoxy groups and –NH₂ groups in the modified soy-based adhesives. FTIR analysis confirmed the cross-linking structure in the cured adhesives. Viscosity and the solid content of soy-based adhesives gradually increased with the increasing amount of epoxy resin, but had little effect on its operability. Wet shear strength of plywood samples increased as the amount of epoxy resin was increased, whereas the inverse trend was observed regarding the water absorption of cured adhesives. Compared to an unmodified adhesive, the addition of 30% of epoxy resin increased the wet shear strength of plywood samples by 58.3% (0.95 MPa), meeting the requirement of the Chinese National Standard for exterior plywood. Differential scanning calorimetry and thermogravimetric analysis showed the improved thermostability of the cured adhesives after curing at 160 °C. These results suggest that epoxy resin could effectively improve the performance of enzyme-treated soy-based adhesives, which might provide a new option for the preparation of soy-based adhesives with high gluability and water resistance. Full article

(This article belongs to the Collection Polymeric Adhesives)

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9 pages, 2892 KiB

Open AccessArticle

A Single-Site Iron(III)-Salan Catalyst for Converting COS to Sulfur-Containing Polymers

by Ge-Ge Gu, Tian-Jun Yue, Zhao-Qian Wan, Rong Zhang, Xiao-Bing Lu

and Wei-Min Ren^*

Key Laboratory of Fine Chemicals, Dalian University of Technology, 2 Linggong Road, Dalian 116012, China

Polymers 2017, 9(10), 515; https://doi.org/10.3390/polym9100515 - 17 Oct 2017

Cited by 21 | Viewed by 5726

Abstract

An iron(III) complex of tetradentate N,N′-disubstituted bis(aminophenoxide) (designated as salan, a saturated version of the corresponding salen ligand) with a sterically hindered organic base anchored on the ligand framework, can selectively mediate the conversion of carbonyl sulfide to sulfur-containing polymers [...] Read more.

An iron(III) complex of tetradentate N,N′-disubstituted bis(aminophenoxide) (designated as salan, a saturated version of the corresponding salen ligand) with a sterically hindered organic base anchored on the ligand framework, can selectively mediate the conversion of carbonyl sulfide to sulfur-containing polymers by the copolymerization with epoxides. This single-site catalyst exhibits broad substrate scope, and the resultant copolymers have completely alternating structures. In addition, this catalyst is efficient in producing diblock copolymers, suggesting a living polymerization nature. Full article

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

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10 pages, 2007 KiB

Open AccessArticle

Medium Bandgap D-A Type Photovoltaic Polymers Based on an Asymmetric Dithienopyran Donor and a Benzotriazole Acceptor

by Junyi Hu^1,2, Xiaochen Wang^1,*, Fan Chen^1,2, Bo Xiao^1,2, Ailing Tang¹ and Erjun Zhou^1,*

¹ CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China

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

Polymers 2017, 9(10), 516; https://doi.org/10.3390/polym9100516 - 17 Oct 2017

Cited by 8 | Viewed by 5320

Abstract

Conjugated polymers based on the donor of an asymmetric 5H-dithieno[3,2-b:2′,3′-d]pyran (DTPa) and the acceptors of benzo[d][1,2,3]triazole (BTA) or di-fluorinated benzo[d][1,2,3]triazole (ffBTA) with thiophene as π-bridge were designed and synthesized. Two asymmetric-building-block-containing polymers (ABC-polymers) possess a [...] Read more.

Conjugated polymers based on the donor of an asymmetric 5H-dithieno[3,2-b:2′,3′-d]pyran (DTPa) and the acceptors of benzo[d][1,2,3]triazole (BTA) or di-fluorinated benzo[d][1,2,3]triazole (ffBTA) with thiophene as π-bridge were designed and synthesized. Two asymmetric-building-block-containing polymers (ABC-polymers) possess a strong and broad absorption in the range of 300–750 nm and medium optical bandgap of 1.73 and 1.77 eV for PDTPa-TBTA and PDTPa-TffBTA, respectively. Polymer solar cells using PDTPa-TBTA as donor and [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as an acceptor exhibited power conversion efficiencies (PCE) of 2.22% with a V_oc of 0.58 V, a J_sc of 6.04 mA/cm², and an FF of 63.41%. The introduction of fluorine substituents on the BTA unit evidently influenced the optical and photovoltaic properties. Interestingly, although the HOMO energy level indeed decreased, PDTPa-TffBTA showed a decreased V_oc of 0.52 V in solar cells. Combined with an obviously enhanced J_sc of 10.23 mA/cm², and an outstanding FF of 0.64, the PCE of solar cells based on PDTPa-TffBTA was improved by nearly 55%, reached 3.43%. Our results indicate that the BTA unit can be used to construct ABC polymers with a medium bandgap, and the introduction of fluorine on the BTA unit is also effective in improving the photovoltaic performance. Full article

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

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13 pages, 2101 KiB

Open AccessArticle

Interactions of Biocidal Polyhexamethylene Guanidine Hydrochloride and Its Analogs with POPC Model Membranes

by Xuliang Luo^1,2, Ziran Jiang^1,2, Niya Zhang¹, Zixin Yang³ and Zhongxin Zhou^1,2,*

¹ Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Sciences & Technology, Huazhong Agriculture University, 1 Shizishan Street, Wuhan 430070, China

² The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agriculture University, 1 Shizishan Street, Wuhan 430070, China

³ College of Sciences, Huazhong Agriculture University, 1 Shizishan Street, Wuhan 430070, China

Polymers 2017, 9(10), 517; https://doi.org/10.3390/polym9100517 - 17 Oct 2017

Cited by 15 | Viewed by 6049

Abstract

The bacterial membrane-targeted polyhexamethylene guanidine hydrochloride (PHGH) and its novel analog polyoctamethylene guanidine hydrochloride (POGH) had excellent antimicrobial activities against antibiotics-resistant bacteria. However, the biocompatibility aspects of PHGH and POGH on the phospholipid membrane of the eukaryotic cell have not yet been considered. [...] Read more.

The bacterial membrane-targeted polyhexamethylene guanidine hydrochloride (PHGH) and its novel analog polyoctamethylene guanidine hydrochloride (POGH) had excellent antimicrobial activities against antibiotics-resistant bacteria. However, the biocompatibility aspects of PHGH and POGH on the phospholipid membrane of the eukaryotic cell have not yet been considered. Four chemically synthesized cationic oligoguanidine polymers containing alkyl group with different carbon chain lengths, including PHGH, POGH, and their two analogs, were used to determine their interactions with zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipids vesicles mimicking the eukaryotic cell membrane. Characterization was conducted by using bactericidal dynamics, hemolysis testing, calcein dye leakage, and isothermal titration calorimetry. Results showed that the gradually lengthened alkyl carbon chain of four oligoguanidine polymers increased the biocidal activity of the polymer, accompanied with the increased hemolytic activity, calcein dye leakage rate and the increased absolute value of the exothermic effect of polymer-POPC membrane interaction. The thermodynamic curve of the polymer-POPC membrane interaction exhibited a very weak exothermic effect and a poorly unsaturated titration curve, which indicated that four guanidine polymers had weak affinity for zwitterionic POPC vesicles. Generally, PHGH of four guanidine polymers had high biocidal activity and relatively high biocompatibility. This study emphasized that appropriate amphiphilicity balanced by the alkyl chain length, and the positive charge is important factor for the biocompatibility of cationic antimicrobial guanidine polymer. Both PHGH and POGH exhibited destructive power to phospholipid membrane of eukaryotic cell, which should be considered in their industry applications. Full article

(This article belongs to the Special Issue Antimicrobial Polymers)

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16 pages, 7133 KiB

Open AccessArticle

Electrosynthesis of Copolymers Based on 1,3,5-Tris(N-Carbazolyl)Benzene and 2,2′-Bithiophene and Their Applications in Electrochromic Devices

by Chung-Wen Kuo^* and Po-Ying Lee

Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

Polymers 2017, 9(10), 518; https://doi.org/10.3390/polym9100518 - 17 Oct 2017

Cited by 21 | Viewed by 5734

Abstract

Poly(1,3,5-tris(N-carbazolyl)benzene) (PtnCz) and three copolymers based on 1,3,5-tris(N-carbazolyl)benzene (tnCz) and 2,2′-bithiophene (bTp) were electrochemically synthesized. The anodic P(tnCz1-bTp2) film with a tnCz/bTp feed molar ratio of 1/2 showed four colors (light orange at 0.0 V, yellowish-orange at 0.7 V, [...] Read more.

Poly(1,3,5-tris(N-carbazolyl)benzene) (PtnCz) and three copolymers based on 1,3,5-tris(N-carbazolyl)benzene (tnCz) and 2,2′-bithiophene (bTp) were electrochemically synthesized. The anodic P(tnCz1-bTp2) film with a tnCz/bTp feed molar ratio of 1/2 showed four colors (light orange at 0.0 V, yellowish-orange at 0.7 V, yellowish-green at 0.8 V, and blue at 1.1 V) from the neutral state to oxidized states. The optical contrast (∆T%) and coloration efficiency (η) of the P(tnCz1-bTp2) film were measured as 48% and 112 cm²∙C⁻¹, respectively, at 696 nm. Electrochromic devices (ECDs) based on PtnCz, P(tnCz1-bTp1), P(tnCz1-bTp2), P(tnCz1-bTp4), and PbTp films as anodic polymer layers and poly(3,4-dihydro-3,3-dimethyl-2H-thieno[3,4-b-1,4]dioxepin) (PProDOT-Me₂) as cathodic polymer layers were assembled. P(tnCz1-bTp2)/PProDOT-Me₂ ECD showed three various colors (saffron yellow, yellowish-blue, and dark blue) at potentials ranging from −0.3 to 1.5 V. In addition, P(tnCz1-bTp2)/PProDOT-Me₂ ECD showed a high ∆T% value (40% at 630 nm) and a high coloration efficiency (519 cm²∙C⁻¹ at 630 nm). Full article

(This article belongs to the Special Issue Smart Polymers)

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17 pages, 3761 KiB

Open AccessArticle

Modeling the Temperature Dependence of Dynamic Mechanical Properties and Visco-Elastic Behavior of Thermoplastic Polyurethane Using Artificial Neural Network

by Ivan Kopal^1,2,*, Marta Harničárová^1,3, Jan Valíček^1,3,4 and Milena Kušnerová^1,3

¹ Institute of Physics, Faculty of Mining and Geology, Vysoká škola báňská—Technical University of Ostrava, 17. Listopadu 15, 708 33 Ostrava, Czech Republic

² Department of Numerical Methods and Computing Modelling, Faculty of Industrial Technologies in Púchov, Alexander Dubček University of Trenčín, Ivana Krasku 491/30, 020 01 Puchov, Slovakia

³ Regional Materials Science and Technology Centre, Vysoká škola báňská—Technical University of Ostrava, 17. Listopadu 15, 708 33 Ostrava, Czech Republic

⁴ Technical Faculty, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 949 76 Nitra, Slovakia

Polymers 2017, 9(10), 519; https://doi.org/10.3390/polym9100519 - 18 Oct 2017

Cited by 41 | Viewed by 8320

Abstract

This paper presents one of the soft computing methods, specifically the artificial neural network technique, that has been used to model the temperature dependence of dynamic mechanical properties and visco-elastic behavior of widely exploited thermoplastic polyurethane over the wide range of temperatures. It [...] Read more.

This paper presents one of the soft computing methods, specifically the artificial neural network technique, that has been used to model the temperature dependence of dynamic mechanical properties and visco-elastic behavior of widely exploited thermoplastic polyurethane over the wide range of temperatures. It is very complex and commonly a highly non-linear problem with no easy analytical methods to predict them directly and accurately in practice. Variations of the storage modulus, loss modulus, and the damping factor with temperature were obtained from the dynamic mechanical analysis tests across transition temperatures at constant single frequency of dynamic mechanical loading. Based on dynamic mechanical analysis experiments, temperature dependent values of both dynamic moduli and damping factor were calculated by three models of well-trained multi-layer feed-forward back-propagation artificial neural network. The excellent agreement between the modeled and experimental data has been found over the entire investigated temperature interval, including all of the observed relaxation transitions. The multi-layer feed-forward back-propagation artificial neural network has been confirmed to be a very effective artificial intelligence tool for the modeling of dynamic mechanical properties and for the prediction of visco-elastic behavior of tested thermoplastic polyurethane in the whole temperature range of its service life. Full article

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31 pages, 7351 KiB

Open AccessFeature PaperReview

Development of Solution-Processable, Optically Transparent Polyimides with Ultra-Low Linear Coefficients of Thermal Expansion

by Masatoshi Hasegawa

Department of Chemistry, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan

Polymers 2017, 9(10), 520; https://doi.org/10.3390/polym9100520 - 18 Oct 2017

Cited by 156 | Viewed by 19719

Abstract

This paper reviews the development of new high-temperature polymeric materials applicable to plastic substrates in image display devices with a focus on our previous results. Novel solution-processable colorless polyimides (PIs) with ultra-low linear coefficients of thermal expansion (CTE) are proposed in this paper. [...] Read more.

This paper reviews the development of new high-temperature polymeric materials applicable to plastic substrates in image display devices with a focus on our previous results. Novel solution-processable colorless polyimides (PIs) with ultra-low linear coefficients of thermal expansion (CTE) are proposed in this paper. First, the principles of the coloration of PI films are briefly discussed, including the influence of the processing conditions on the film coloration, as well as the chemical and physical factors dominating the low CTE characteristics of the resultant PI films to clarify the challenges in simultaneously achieving excellent optical transparency, a very high T_g, a very low CTE, and excellent film toughness. A possible approach of achieving these target properties is to use semi-cycloaliphatic PI systems consisting of linear chain structures. However, semi-cycloaliphatic PIs obtained using cycloaliphatic diamines suffer various problems during precursor polymerization, cyclodehydration (imidization), and film preparation. In particular, when using trans-1,4-cyclohexanediamine (t-CHDA) as the cycloaliphatic diamine, a serious problem emerges: salt formation in the initial stages of the precursor polymerization, which terminates the polymerization in some cases or significantly extends the reaction period. The system derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) and t-CHDA can be polymerized by a controlled heating method and leads to a PI film with relatively good properties, i.e., excellent light transmittance at 400 nm (T₄₀₀ = ~80%), a high T_g (>300 °C), and a very low CTE (10 ppm·K⁻¹). However, this PI film is somewhat brittle (the maximum elongation at break, ε_{b max} is about 10%). On the other hand, the combination of cycloaliphatic tetracarboxylic dianhydrides and aromatic diamines does not result in salt formation. The steric structures of cycloaliphatic tetracarboxylic dianhydrides significantly influence the polymerizability with aromatic diamines and the CTE values of the resultant PI films. For three isomers of hydrogenated pyromellitic dianhydride, the steric structure effect on the polymerizability and the properties of the PI films is discussed. 1,2,3,4-Cyclobutanetetracarboxylic dianhydride (CBDA) is a very unusual cycloaliphatic tetracarboxylic dianhydride that is suitable for reducing the CTE. For example, the PI system derived from CBDA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) yields a colorless PI film with a relatively low CTE (21 ppm·K⁻¹). However, this PI is insoluble in common organic solvents, which means that it is neither solution-processable nor compatible with the chemical imidization process; furthermore, the film is somewhat brittle (ε_b < 10%). In addition, the effect of the film preparation route on the film properties is shown to be significant. Films prepared via chemical imidization always have higher optical transparency and lower CTE values than those prepared via the conventional two-step process (i.e., precursor casting and successive thermal imidization). These results suggest that compatibility with the chemical imidization process is the key for achieving our goal. To dramatically improve the solubility in the CBDA-based PI systems, a novel amide-containing aromatic diamine (AB-TFMB), which possesses the structural features of TFMB and 4,4′-diaminobenzanilide (DABA), is proposed. The CBDA(70);6FDA(30)/AB-TFMB copolymer has an ultra-low CTE (7.3 ppm·K⁻¹), excellent optical transparency (T₄₀₀ = 80.6%, yellowness index (YI) = 2.5, and haze = 1.5%), a very high T_g (329 °C), sufficient ductility (ε_{b max} > 30%), and good solution-processability. Therefore, this copolymer is a promising candidate for use as a novel coating-type plastic substrate material. This paper also discusses how the target properties can be achieved without the help of cycloaliphatic monomers. Thus, elaborate molecular design allows the preparation of highly transparent and low-CTE aromatic poly(amide imide) and poly(ester imide) systems. Full article

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

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17 pages, 4193 KiB

Open AccessFeature PaperReview

(Cryo)Transmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

by Annette Meister^1,2,* and Alfred Blume¹

¹ Institute of Chemistry, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany

² Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany

Polymers 2017, 9(10), 521; https://doi.org/10.3390/polym9100521 - 19 Oct 2017

Cited by 29 | Viewed by 17099

Abstract

Lipid membranes can incorporate amphiphilic or polyphilic molecules leading to specific functionalities and to adaptable properties of the lipid bilayer host. The insertion of guest molecules into membranes frequently induces changes in the shape of the lipid matrix that can be visualized by [...] Read more.

Lipid membranes can incorporate amphiphilic or polyphilic molecules leading to specific functionalities and to adaptable properties of the lipid bilayer host. The insertion of guest molecules into membranes frequently induces changes in the shape of the lipid matrix that can be visualized by transmission electron microscopy (TEM) techniques. Here, we review the use of stained and vitrified specimens in (cryo)TEM to characterize the morphology of amphiphilic and polyphilic molecules upon insertion into phospholipid model membranes. Special emphasis is placed on the impact of novel synthetic amphiphilic and polyphilic bolalipids and polymers on membrane integrity and shape stability. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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17 pages, 6969 KiB

Open AccessArticle

Evaluation of Thermal and Thermomechanical Behaviour of Bio-Based Polyamide 11 Based Composites Reinforced with Lignocellulosic Fibres

by Helena Oliver-Ortega¹

, José Alberto Méndez¹

, Pere Mutjé¹, Quim Tarrés^1,*

, Francesc Xavier Espinach²

and Mònica Ardanuy³

¹ Group LEPAMAP, Department of Chemical Engineering, University of Girona, C/M.Aurèlia Capmany, 61, 17003 Girona, Spain

² Design, Development and Product Innovation, Dpt. Organization, Business Management and Product Design, University of Girona, C/M.Aurèlia Capmany, 61, 17003 Girona, Spain

³ Departament de Ciència dels Materials i Enginyeria Metal.lúrgica, Secció Enginyeria Tèxtil, Universitat Politècnica de Catalunya, C/Colom, 11, 08222 Terrassa, Barcelona, Spain

Polymers 2017, 9(10), 522; https://doi.org/10.3390/polym9100522 - 18 Oct 2017

Cited by 32 | Viewed by 8199

Abstract

In this work, polyamide 11 (PA11) and stone ground wood fibres (SGW) were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of [...] Read more.

In this work, polyamide 11 (PA11) and stone ground wood fibres (SGW) were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of PA11-based composites were studied. Natural fibres have lower degradation temperatures than PA11, thus, composites showed lower onset degradation temperatures than PA11, as well. The thermal transition and the semi-crystalline structure of the composites were similar to PA11. On the other hand, when SGW was submitted to an annealing treatment, the composites prepared with these fibres increased its crystallinity, with increasing fibre contents, compared to PA11. The differences between the glass transition temperatures of annealed and untreated composites decreased with the fibre contents. Thus, the fibres had a higher impact in the composites mechanical behaviour than on the mobility of the amorphous phase. The crystalline structure of PA11 and PA11-SGW composites, after annealing, was transformed to α’ more stable phase, without any negative impact on the properties of the fibres. Full article

(This article belongs to the Collection Polysaccharides)

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26 pages, 4683 KiB

Open AccessReview

The Recent Developments in Biobased Polymers toward General and Engineering Applications: Polymers that are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

by Hajime Nakajima, Peter Dijkstra and Katja Loos^*

Macromolecular Chemistry and New Polymeric Materials, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

Polymers 2017, 9(10), 523; https://doi.org/10.3390/polym9100523 - 18 Oct 2017

Cited by 351 | Viewed by 33242

Abstract

The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering [...] Read more.

The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering applications. This expansion is driven by the remarkable progress in the processes for refining biomass feedstocks to produce biobased building blocks that allow biobased polymers to have more versatile and adaptable polymer chemical structures and to achieve target properties and functionalities. In this review, biobased polymers are categorized as those that are: (1) upgrades from biodegradable polylactides (PLA), polyhydroxyalkanoates (PHAs), and others; (2) analogous to petroleum-derived polymers such as bio-poly(ethylene terephthalate) (bio-PET); and (3) new biobased polymers such as poly(ethylene 2,5-furandicarboxylate) (PEF). The recent developments and progresses concerning biobased polymers are described, and important technical aspects of those polymers are introduced. Additionally, the recent scientific achievements regarding high-spec engineering-grade biobased polymers are presented. Full article

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

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12 pages, 8680 KiB

Open AccessArticle

Microstructure and Performance of a Porous Polymer Membrane with a Copper Nano-Layer Using Vapor-Induced Phase Separation Combined with Magnetron Sputtering

by Nana Li^*, Yuanjing Fu, Qingchen Lu and Changfa Xiao

State Key Laboratory of Separation Membranes and Membrane Processes/National Center for International Joint Research on Separation Membranes, Tianjin Polytechnic University, Tianjin 300387, China

Polymers 2017, 9(10), 524; https://doi.org/10.3390/polym9100524 - 18 Oct 2017

Cited by 13 | Viewed by 5725

Abstract

Antibacterial metalized poly(vinylidene fluoride) (PVDF) porous membranes with a nano-layer were obtained via the method of vapor-induced phase separation combined with magnetron sputtering of copper. Magnetron sputtering has such advantages as high deposition rates, low substrate temperatures, and good adhesion of films on [...] Read more.

Antibacterial metalized poly(vinylidene fluoride) (PVDF) porous membranes with a nano-layer were obtained via the method of vapor-induced phase separation combined with magnetron sputtering of copper. Magnetron sputtering has such advantages as high deposition rates, low substrate temperatures, and good adhesion of films on substrates. The influence brought by deposition time on the microstructure, hydrophobic property, copper distribution state, anti-biofouling, and permeation separation performance was investigated via atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectrometry, contact angle measurements, and capillary flow porometry, along with the porosity, water flux, protein solution flux, rejection rate, water flux recovery rate, and antibacterial property. The results showed that copper particles formed island-type deposits on the membrane surface and were embedded into cross-section pores near the surface owning to the interconnection of pores. Subsequently, the water flux and protein solution flux declined, but the rejection rate and water flux recovery rate increased. Meanwhile, Cu-coated PVDF membranes exhibited an excellent antibacterial ability. Full article

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

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10 pages, 10965 KiB

Open AccessArticle

Perpendicular Structure Formation of Block Copolymer Thin Films during Thermal Solvent Vapor Annealing: Solvent and Thickness Effects

by Qiuyan Yang

and Katja Loos^*

Macromolecular Chemistry & New Polymeric Materials, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

Polymers 2017, 9(10), 525; https://doi.org/10.3390/polym9100525 - 18 Oct 2017

Cited by 15 | Viewed by 14610

Abstract

Solvent vapor annealing of block copolymer (BCP) thin films can produce a range of interesting morphologies, especially when the perpendicular orientation of micro-domains with respect to the substrate plays a role. This, for instance, allows BCP thin films to serve as useful templates [...] Read more.

Solvent vapor annealing of block copolymer (BCP) thin films can produce a range of interesting morphologies, especially when the perpendicular orientation of micro-domains with respect to the substrate plays a role. This, for instance, allows BCP thin films to serve as useful templates for nanolithography and hybrid materials preparation. However, precise control of the arising morphologies is essential, but in most cases difficult to achieve. In this work, we investigated the solvent and thickness effects on the morphology of poly(styrene-b-2 vinyl pyridine) (PS-b-P2VP) thin films with a film thickness range from 0.4 L₀ up to 0.8 L₀. Ordered perpendicular structures were achieved. One of the main merits of our work is that the phase behavior of the ultra-high molecular weight BCP thin films, which hold a 100-nm sized domain distance, can be easily monitored via current available techniques, such as scanning electron microscope (SEM), atomic force microscope (AFM), and transmission electron microscope (TEM). Systematic monitoring of the self-assembly behavior during solvent vapor annealing can thus provide an experimental guideline for the optimization of processing conditions of related BCP films systems. Full article

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12 pages, 3210 KiB

Open AccessArticle

Facile Cellulose Dissolution and Characterization in the Newly Synthesized 1,3-Diallyl-2-ethylimidazolium Acetate Ionic Liquid

by Hui Zhang¹, Yaoguang Xu¹, Yuqi Li¹

, Zexiang Lu¹, Shilin Cao¹, Mizi Fan^1,2, Liulian Huang^1,* and Lihui Chen^1,*

¹ College of Materials Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China

² Nanocellulose and Biocomposites Research Centre, College of Engineering, Design and Physical Sciences, Brunel University London, Middlesex UB8 3PH, UK

Polymers 2017, 9(10), 526; https://doi.org/10.3390/polym9100526 - 18 Oct 2017

Cited by 38 | Viewed by 8509

Abstract

A facile cellulose solvent 1,3-diallyl-2-ethylimidazolium acetate ([AAeim][OAc]) with high electrical conductivity has been designed and synthesized for the first time, via a quaternization reaction and ion exchange method. The dissolution characteristics of cellulose in this solvent were studied in detail. Meanwhile, the co-solvent [...] Read more.

A facile cellulose solvent 1,3-diallyl-2-ethylimidazolium acetate ([AAeim][OAc]) with high electrical conductivity has been designed and synthesized for the first time, via a quaternization reaction and ion exchange method. The dissolution characteristics of cellulose in this solvent were studied in detail. Meanwhile, the co-solvent system was designed by adding an aprotic polar solvent dimethyl sulfoxide (DMSO) in [AAeim][OAc]. The effects of temperature and the mass ratio of DMSO to [AAeim][OAc] on the solubility of cellulose were studied. Furthermore, the effects of regeneration on the molecular structure and thermal stability of cellulose were determined by Fourier transform infrared spectroscopy (FT-IR), thermal gravity analysis (TGA) and X-ray diffraction (XRD). The findings revealed that the synthesized ionic liquid (IL) has a relatively low viscosity, high conductivity and a good dissolving capacity for bamboo dissolving pulp cellulose (Degree of Polymerization: DP = 650). The macromolecular chain of the cellulose is less damaged during the dissolution and regeneration process. Due to the increased number of “free” anions [OAc]⁻and cations [AAeim]⁺, the addition of DMSO can significantly increase the solubility of the cellulose up to 12 wt % at the mass ratio of 3:1, indicating that the synthesized IL has a potential application in the electrospinning field. Full article

(This article belongs to the Collection Polysaccharides)

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17 pages, 5519 KiB

Open AccessArticle

A New Insight in Determining the Percolation Threshold of Electrical Conductivity for Extrinsically Conducting Polymer Composites through Different Sigmoidal Models

by Mostafizur Rahaman^1,*

, Ali Aldalbahi^1,*

, Periyasami Govindasami¹, Noorunnisa P. Khanam², Subhendu Bhandari³, Peter Feng⁴ and Tariq Altalhi⁵

¹ Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia

² Department of Mechanical and Industrial Engineering, Qatar University, Doha 2713, Qatar

³ Department of Plastics and Polymer Engineering, Maharashtra Institute of Technology, Aurangabad, Maharashtra 431010, India

⁴ Department of Physics, University of Puerto Rico, San Juan, PR 00936-8377, USA

⁵ Department of Chemistry, Faculty of Science, Taif University, Taif 21974, Saudi Arabia

Polymers 2017, 9(10), 527; https://doi.org/10.3390/polym9100527 - 19 Oct 2017

Cited by 119 | Viewed by 12879

Abstract

The electrical conductivity of extrinsically conducting polymer composite systems passes through a transition state known as percolation threshold. A discussion has been made on how different Sigmoidal models (S-models), such as Sigmoidal–Boltzmann (SB), Sigmoidal–Dose Response (SD), Sigmoidal–Hill (SH), Sigmoidal–Logistic (SL), and Sigmoidal–Logistic-1 (SL-1), [...] Read more.

The electrical conductivity of extrinsically conducting polymer composite systems passes through a transition state known as percolation threshold. A discussion has been made on how different Sigmoidal models (S-models), such as Sigmoidal–Boltzmann (SB), Sigmoidal–Dose Response (SD), Sigmoidal–Hill (SH), Sigmoidal–Logistic (SL), and Sigmoidal–Logistic-1 (SL-1), can be applied to predict the percolation threshold of electrical conductivity for ethylene vinyl acetate copolymer (EVA) and acrylonitrile butadiene copolymer (NBR) conducting composite systems filled with different carbon fillers. An interesting finding that comes from these observations is that the percolation threshold for electrical conductivity determined by SB and SD models are similar, whereas, the other models give different result when estimated for a particular composite system. This similarity and discrepancy in the results of percolation threshold have been discussed by considering the strength, weakness, and limitation of the models. The percolation threshold value for the composites has also been determined using the classical percolation theory and compared with the sigmoidal models. Moreover, to check the universal applicability, these Sigmoidal models have also been tested on results from some published literature. Finally, it is revealed that, except SL-1 model, the remaining models can successfully be used to determine the percolation threshold of electrical conductivity for extrinsically conductive polymer composites. Full article

(This article belongs to the Special Issue Conductive Polymers 2017)

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18 pages, 5165 KiB

Open AccessArticle

Morphology, Crystallization and Thermal Behaviors of PLA-Based Composites: Wonderful Effects of Hybrid GO/PEG via Dynamic Impregnating

by Shikui Jia^1,2,*, Demei Yu^2,*, Yan Zhu¹, Zhong Wang¹, Ligui Chen¹ and Lei Fu¹

¹ School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723000, China

² School of Science, Xi’an Jiaotong University, Xi’an 710049, China

Polymers 2017, 9(10), 528; https://doi.org/10.3390/polym9100528 - 19 Oct 2017

Cited by 160 | Viewed by 10264

Abstract

In this paper, a dynamic impregnating device, which can generate supersonic vibration with the vacuum-adsorbing field, was used to prepare the hybrid graphene oxide (GO)/polyethylene glycol (PEG). Interestingly, the hybrid GO/PEG under dynamic impregnating and/or internal mixing was introduced into poly-(lactic acid) (PLA) [...] Read more.

In this paper, a dynamic impregnating device, which can generate supersonic vibration with the vacuum-adsorbing field, was used to prepare the hybrid graphene oxide (GO)/polyethylene glycol (PEG). Interestingly, the hybrid GO/PEG under dynamic impregnating and/or internal mixing was introduced into poly-(lactic acid) (PLA) matrix via melting-compounding, respectively. On one hand, compared with the internal mixing, the hybrid GO/PEG with the different component ratio using dynamic impregnation had a better dispersed morphology in the PLA matrix. On the other hand, compared with the high molecular weight (M_w) of PEG, the hybrid GO/PEG with low M_w of PEG had better an exfoliated morphology and significantly improved the heat distortion temperature (HDT) of the PLA matrix. Binding energies results indicate that low M_w of PEG with GO has excellent compatibility. Dispersed morphologies of the hybrid GO/PEG show that the dynamic impregnating had stronger blending capacity than the internal mixing and obviously improved the exfoliated morphology of GO in the PLA. Crystallization behaviors indicate that the hybrid GO/PEG with the low M_w of PEG based on dynamic impregnating effectively enhanced the crystallinity of PLA, and the cold crystallization character of PLA disappeared in the melting process. Moreover, the storage modulus and loss factor of the PLA-based composites were also investigated and their HDT was improved with the introduction of hybrid GO/PEG. Furthermore, a physical model for the dispersed morphology of the hybrid GO/PEG in the PLA matrix was established. Overall, the unique blending technique of hybrid GO/PEG via dynamic impregnating is an effective approach to enhance the property range of PLA and is suitable for many industrial applications. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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10 pages, 607 KiB

Open AccessCommunication

Evaluation of Chitosan and Cellulosic Polymers as Binding Adsorbent Materials to Prevent Aflatoxin B1, Fumonisin B1, Ochratoxin, Trichothecene, Deoxynivalenol, and Zearalenone Mycotoxicoses Through an In Vitro Gastrointestinal Model for Poultry

by Bruno Solís-Cruz¹

, Daniel Hernández-Patlán¹

, Eric Beyssac², Juan D. Latorre³

, Xochitl Hernandez-Velasco⁴, Ruben Merino-Guzman⁴

, Guillermo Tellez^3,*

and Raquel López-Arellano¹

¹ Unidad de Investigación Multidisciplinaria. Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de Mexico, Cuautitlán Izcalli, Estado de Mexico 54714, Mexico

² Clermont-Université, Université d’Auvergne, EA4678, Conception Ingénierie et Développement de L’aliment et du Médicament, 63001 Clermont-Ferrand, France

³ Department of Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA

⁴ Departamento de Medicina y Zootecnia de Aves, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico

Polymers 2017, 9(10), 529; https://doi.org/10.3390/polym9100529 - 19 Oct 2017

Cited by 54 | Viewed by 9254

Abstract

Mycotoxins are secondary toxic metabolites that are produced by fungi representing threats to human and animal health. The objective of this study was to evaluate the adsorption capacity of Chitosan (CHI), and three cellulosic polymers (HPMC, CMC, and MCC), on six mycotoxins (AFB [...] Read more.

Mycotoxins are secondary toxic metabolites that are produced by fungi representing threats to human and animal health. The objective of this study was to evaluate the adsorption capacity of Chitosan (CHI), and three cellulosic polymers (HPMC, CMC, and MCC), on six mycotoxins (AFB₁; FUB₁; OTA; T-2; DON; and, ZEA) using an in vitro digestive model for poultry. The adsorbent capacity of the materials in the supernatant of each compartment was evaluated by a non-competitive chemiluminescent assay. Control groups with no adsorbent material had an adsorption value of 0.00% against all six mycotoxins that were evaluated. All four materials tested showed significant (p < 0.05) binding activity against all of the mycotoxins when compared with the control non-treated group. However HPMC, CMC, and MCC showed better adsorbent capacity when compared with CHI. Full article

(This article belongs to the Collection Polysaccharides)

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13 pages, 5926 KiB

Open AccessArticle

Polyimide Aerogels Cross-Linked with Aminated Ag Nanowires: Mechanically Strong and Tough

by Tianyi Zhang¹, Yan Zhao² and Kai Wang^3,*

¹ School of Material Science & Engineering, Beihang University, Beijing 100191, China

² School of Material Science & Engineering, Beihang University, Beijing 100191, China

³ Key Laboratory of Aerospace Materials and Performance, School of Material Science & Engineering, Beihang University, Beijing 100191, China

Polymers 2017, 9(10), 530; https://doi.org/10.3390/polym9100530 - 19 Oct 2017

Cited by 27 | Viewed by 8669

Abstract

In this study, polyimide (PI)/Ag nanowire (AgNW) nanocomposite aerogels with extremely high mechanical performance have been fabricated utilizing amine-modified AgNWs as mechanical nanoreinforcement particulates and crosslinking agents. Initially, AgNWs were fabricated and surface modified by p-aminothiophenol (PATP), then the aminated AgNWs were [...] Read more.

In this study, polyimide (PI)/Ag nanowire (AgNW) nanocomposite aerogels with extremely high mechanical performance have been fabricated utilizing amine-modified AgNWs as mechanical nanoreinforcement particulates and crosslinking agents. Initially, AgNWs were fabricated and surface modified by p-aminothiophenol (PATP), then the aminated AgNWs were dispersed into polyamide acid solution and aerogels were prepared by supercritical CO₂ drying. Raman and X-ray photoelectron spectroscopy (XPS) spectrometry were carried out on A-AgNWs (aminated Ag nanowires) to prove the successful modification. This functional nanoparticle greatly enhanced the strength and toughness of aerogels without evident increase in densities. Comparing to pure PI aerogels, samples with 2.0 wt % of A-AgNWs had a 148% increase in compression strength and 223% increase in Young’s modulus, which equates to 2.41 and 27.66 MPa, respectively. Simultaneously, the tensile test indicated that aerogels with 2.0 wt % of A-AgNWs had a breaking energy of 40.18 J/m³, which is 112% higher than pure PI aerogels. The results presented herein demonstrate that aminated AgNWs are an innovative cross-linker for PI aerogels and can improve their strength and toughness. These aerogels have excellent potential as high-duty, lightweight porous materials in many areas of application. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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11 pages, 2098 KiB

Open AccessArticle

Cis-1,4-Polymerization of Isoprene by 1,3-Bis(oxazolinymethylidene)isoindoline-Ligated Rare-Earth Metal Dialkyl Complexes

by Chao Yu, Dahai Zhou, Xiangqian Yan, Fei Gao, Li Zhang, Shaowen Zhang^* and Xiaofang Li^*

Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 10081, China

Polymers 2017, 9(10), 531; https://doi.org/10.3390/polym9100531 - 20 Oct 2017

Cited by 18 | Viewed by 6091

Abstract

A series of novel chiral nonmetallocene pincer-type rare-earth metal dialkyl complexes bearing the chiral monoanionic tridentate C₂-symmetric 1,3-bis(oxazolinymethylidene)isoindoline (BOXMI-H) ligand (BOXMI)Ln(CH₂SiMe₃)₂ 1–3 (1: Ln = Sc, yield = 57%; 2: Ln = Lu, yield = 55%; [...] Read more.

A series of novel chiral nonmetallocene pincer-type rare-earth metal dialkyl complexes bearing the chiral monoanionic tridentate C₂-symmetric 1,3-bis(oxazolinymethylidene)isoindoline (BOXMI-H) ligand (BOXMI)Ln(CH₂SiMe₃)₂ 1–3 (1: Ln = Sc, yield = 57%; 2: Ln = Lu, yield = 55%; 3: Ln = Y, yield = 62%) have been prepared in moderate yields via the acid-base reaction between the BOXMI ligand and rare-earth metal tri(trimethylsilylmethyl) complexes. The X-ray diffractions show that both of the complexes 1 and 2 contain one BOXMI ligand and two trimethylsilylmethyl ligands, adopting a distorted trigonal bipyramidal configuration. In the presence of a cocatalyst such as borate and AlR₃, these complexes 1–3 exhibit high activities of up to 6.8 × 10⁴ (g of polymer)/(mol_Ln h) and high cis-1,4 selectivities of up to 97% in the polymerization of isoprene in toluene, yielding the cis-1,4-polyisoprenes with heavy molecular weights (M_n of up to 710,000 g/mol) and bimodal molecular weight distributions (M_w/M_n = 2.0–4.5). Full article

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

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14 pages, 3944 KiB

Open AccessArticle

Effects of Reorientation of Graphene Platelets (GPLs) on Young’s Modulus of Polymer Nanocomposites under Uni-Axial Stretching

by Chuang Feng¹

, Yu Wang¹

, Sritawat Kitipornchai² and Jie Yang^1,*

¹ School of Engineering, RMIT University, P.O. Box 71, Bundoora, VIC 3083, Australia

² School of Civil Engineering, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia

Polymers 2017, 9(10), 532; https://doi.org/10.3390/polym9100532 - 20 Oct 2017

Cited by 39 | Viewed by 6007

Abstract

The orientation of reinforcement fillers in composites plays a vital role in their mechanical properties. This paper employs the Mori–Tanaka micromechanics model, incorporating the effect of stretching-induced reorientation of graphene platelets (GPL), to predict Young’s modulus of GPL/polymer nanocomposites. Subjected to uni-axial stretching, [...] Read more.

The orientation of reinforcement fillers in composites plays a vital role in their mechanical properties. This paper employs the Mori–Tanaka micromechanics model, incorporating the effect of stretching-induced reorientation of graphene platelets (GPL), to predict Young’s modulus of GPL/polymer nanocomposites. Subjected to uni-axial stretching, dispersion of GPLs is described by an orientation distribution function (ODF) in terms of a stretching strain and two Euler angles. The ODF shows that GPLs tend to realign along the stretching direction. Such realignment is enhanced at a higher Poisson’s ratio and under a larger stretching strain. It is found that the out-of-plane Young’s modulus of GPL nanofillers has a limited effect on the overall Young’s modulus of the composites. With an increase in stretching strain and GPL concentration, Young’s modulus increases in the stretching direction while it decreases in the transverse direction. A larger aspect-ratio of GPLs with fewer layers is preferred for enhancing Young’s modulus in the stretching direction, but it is unfavorable in the transverse direction. Moreover, Young’s moduli in both longitudinal and transverse directions are more sensitive to the reorientation of smaller-sized GPLs with a greater concentration in the composites. Full article

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15 pages, 6044 KiB

Open AccessArticle

Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation

by Daomin Min^1,2,*, Chenyu Yan¹, Yin Huang¹, Shengtao Li¹ and Yoshimichi Ohki^1,2,3

¹ State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China

² Research Institute for Materials Science and Technology, Waseda University, Shinjuku, Tokyo 169-8555, Japan

³ Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555, Japan

Polymers 2017, 9(10), 533; https://doi.org/10.3390/polym9100533 - 20 Oct 2017

Cited by 57 | Viewed by 9699

Abstract

Silicone rubber (SiR) is used as an insulating material for cables installed in a nuclear power plant. Gamma rays irradiated SiR sheets for various periods at temperatures of 145 and 185 °C, and the resultant changes were analyzed by examining complex permittivity spectra [...] Read more.

Silicone rubber (SiR) is used as an insulating material for cables installed in a nuclear power plant. Gamma rays irradiated SiR sheets for various periods at temperatures of 145 and 185 °C, and the resultant changes were analyzed by examining complex permittivity spectra and surface potential decay characteristics. Three different processes, namely, instantaneous polarization, electrode polarization due to the accumulation of ions to form double charge layers at dielectric/electrode interfaces, and DC conduction caused by directional hopping of ions, contribute to the complex permittivity. By fitting the spectra to theoretical equations, we can obtain the dielectric constant at high frequencies, concentration and diffusion coefficient of ions and DC conductivity for the pristine and degraded samples. The instantaneous polarization becomes active with an increase of dose and ageing temperature. The thermal expansion coefficient estimated from the temperature dependence of dielectric constant at high frequencies becomes smaller with an increase in dose, which is in good agreement with the experimental results of the swelling ratio. Additionally, trap distributions are calculated from surface potential decay measurements and analyzed to explain the variation in conductivity. Trap energy increases firstly, and then decreases with an increase in dose, leading to a similar change in DC conductivity. It is concluded that generations of both oxidative products and mobile ions, as well as the occurrence of chain scission and crosslinking are simultaneously induced by gamma rays. Full article

(This article belongs to the Collection Silicon-Containing Polymeric Materials)

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37 pages, 20672 KiB

Open AccessReview

Fifty Years of Hydrosilylation in Polymer Science: A Review of Current Trends of Low-Cost Transition-Metal and Metal-Free Catalysts, Non-Thermally Triggered Hydrosilylation Reactions, and Industrial Applications

by Robin J. Hofmann^1,2, Matea Vlatković¹ and Frank Wiesbrock^1,*

¹ Polymer Competence Center Leoben GmbH (PCCL), Roseggerstrasse 12, 8700 Leoben, Austria

² Institute for Chemistry and Technology of Materials, Graz University of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz, Austria

Polymers 2017, 9(10), 534; https://doi.org/10.3390/polym9100534 - 20 Oct 2017

Cited by 128 | Viewed by 23526

Abstract

Hydrosilylation reactions, the (commonly) anti-Markovnikov additions of silanes to unsaturated bonds present in compounds such as alkenes and alkynes, offer numerous unique and advantageous properties for the preparation of polymeric materials, such as high yields and stereoselectivity. These reactions require to be catalyzed, [...] Read more.

Hydrosilylation reactions, the (commonly) anti-Markovnikov additions of silanes to unsaturated bonds present in compounds such as alkenes and alkynes, offer numerous unique and advantageous properties for the preparation of polymeric materials, such as high yields and stereoselectivity. These reactions require to be catalyzed, for which platinum compounds were used in the initial stages. Celebrating the 50th anniversary of hydrosilylations in polymer science and, concomitantly, five decades of continuously growing research, hydrosilylation reactions have advanced to a level that renders them predestined for transfer into commercial products on the large scale. Facing this potential transfer, this review addresses and discusses selected current trends of the scientific research in the area, namely low-cost transition metal catalysts (focusing on iron, cobalt, and nickel complexes), metal-free catalysts, non-thermally triggered hydrosilylation reactions (highlighting stimuli such as (UV-)light), and (potential) industrial applications (highlighting the catalysts used and products manufactured). This review focuses on the hydrosilylation reactions involving alkene reactants. Full article

(This article belongs to the Collection Silicon-Containing Polymeric Materials)

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22 pages, 4051 KiB

Open AccessReview

Self-Healing Polymeric Composite Material Design, Failure Analysis and Future Outlook: A Review

by Keletso Mphahlele^1,2, Suprakas Sinha Ray^1,3,*

and Andrei Kolesnikov²

¹ DST-CSIR National Centre for Nanostructured Materials, Council for Scientific and Industrial Research, Pretoria 0001, South Africa

² Department of Chemical, Metallurgical and Material Engineering, Tshwane University of Technology, Pretoria 0001, South Africa

³ Department of Applied Chemistry, University of Johannesburg, Doornfontein, Johannesburg 2028, South Africa

Polymers 2017, 9(10), 535; https://doi.org/10.3390/polym9100535 - 20 Oct 2017

Cited by 62 | Viewed by 16288

Abstract

The formation of micro-cracks and crack propagation is still an acute problem in polymer and polymer composites. These micro-cracks usually occur while the materials are manufactured or serviced. The development and coalescence of these cracks reduces the lifespan and brings about a catastrophic [...] Read more.

The formation of micro-cracks and crack propagation is still an acute problem in polymer and polymer composites. These micro-cracks usually occur while the materials are manufactured or serviced. The development and coalescence of these cracks reduces the lifespan and brings about a catastrophic failure of the materials. Novel scientific research on polymeric self-healing is emphasised in a number of publications, which consist of contributions from many of the prominent researchers in this area. Progress in this field can eventually enable scientist to construct new flexible materials that both monitor the material’s integrity and repair the deformed material prior to the occurrence of any fatal failures. This report describes recent trends that have been used in material science and computational methods to mitigate the development of micro-cracks and crack propagation in polymer composites. Full article

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9 pages, 1325 KiB

Open AccessArticle

A Concise Synthesis of Three Branches Derived from Polysaccharide RN1 and Anti-Pancreatic Cancer Activity Study

by Deqin Cai^1,2, Yanli Yao^1,2, Yubo Tang^3,4, Zheng Wang^2,5, Wei Shi^1,3, Wei Huang^1,3 and Kan Ding^1,2,*

¹ University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China

² Glycochemistry and Glycobiology Lab, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China

³ CAS Key Laboratory of Receptor Research, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Pudong, Shanghai 201203, China

⁴ Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China

⁵ Nano Science and Technology Institute, University of Science and Technology of China, 96 Jin Zhai Road, Hefei 230026, China

Polymers 2017, 9(10), 536; https://doi.org/10.3390/polym9100536 - 21 Oct 2017

Cited by 5 | Viewed by 5656

Abstract

RN1, a polysaccharide from flowers of Panax pseudo-ginsieng Wall. Var. notoginseng (Burkill) Hoo & Tseng, is a potential multi-targeting drug candidate for pancreatic cancer treatment. However, the active targeting domain of RN1 is still unknown. Herein, three RN1 derived branches were synthesized via [...] Read more.

RN1, a polysaccharide from flowers of Panax pseudo-ginsieng Wall. Var. notoginseng (Burkill) Hoo & Tseng, is a potential multi-targeting drug candidate for pancreatic cancer treatment. However, the active targeting domain of RN1 is still unknown. Herein, three RN1 derived branches were synthesized via [3+2] or [2+2] strategies, efficiently. Two pentasaccharides, 18 and 27, showed similar inhibition effect on pancreatic cancer BxPC-3 cells to that of RN1 at same concentration. Interestingly, tetrasaccharide 21 potently inhibited gemcitabineresistant cell line Panc-1 at high concentration. These suggest that the branches of RN1 might be the active targeting domain and tetrasaccharide 21 might be a potential leading compound for pancreatic cancer with gemcitabine resistance. Full article

(This article belongs to the Special Issue Polysaccharides)

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14 pages, 4765 KiB

Open AccessArticle

Effect of Moisture on Mechanical Properties and Thermal Stability of Meta-Aramid Fiber Used in Insulating Paper

by Fei Yin¹, Chao Tang^1,2,*, Xu Li¹ and Xiaobo Wang¹

¹ College of Engineering and Technology, Southwest University, Chongqing 400715, China

² School of Electronics and Computer Science, University of Southampton, SO171BJ Southampton, UK

Polymers 2017, 9(10), 537; https://doi.org/10.3390/polym9100537 - 22 Oct 2017

Cited by 46 | Viewed by 7845

Abstract

Seven composite models of meta-aramid fibers with different moisture contents were studied using molecular dynamics simulation. The effects of moisture on the thermal stability and mechanical properties of the fibers and their mechanisms were analyzed, considering characteristics such as hydrogen bonding, free volume, [...] Read more.

Seven composite models of meta-aramid fibers with different moisture contents were studied using molecular dynamics simulation. The effects of moisture on the thermal stability and mechanical properties of the fibers and their mechanisms were analyzed, considering characteristics such as hydrogen bonding, free volume, mean square displacement, and mechanical parameters. The simulation results showed that the large number of hydrogen bonds between water molecules and meta-aramid fibers destroyed the original hydrogen-bond network. Hydrogen bonds between the molecular chains of meta-aramid fibers were first destroyed, and their number decreased with increasing moisture content. The free volume of the fibers thereby increased, the interactions between fiber chains weakened with increasing moisture content, and the fiber chain movement intensified accordingly. The ratio of diffusion coefficients of the water molecules to moisture contents of the composite models increased linearly, and the water molecule diffusion increased, which accelerated the rate of damage to the original hydrogen-bond network of the meta-aramid fibers and further reduced their thermal stability. In general, the mechanical properties of the composites were negatively related to their moisture content. Full article

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14 pages, 4138 KiB

Open AccessArticle

Anionic Polymerization of Styrene and 1,3-Butadiene in the Presence of Phosphazene Superbases

by Konstantinos Ntetsikas¹

, Yahya Alzahrany¹, George Polymeropoulos¹

, Panayiotis Bilalis¹, Yves Gnanou² and Nikos Hadjichristidis^1,*

¹ Polymer Synthesis Laboratory, KAUST Catalysis Center, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia

² Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia

Polymers 2017, 9(10), 538; https://doi.org/10.3390/polym9100538 - 21 Oct 2017

Cited by 18 | Viewed by 13145

Abstract

The anionic polymerization of styrene and 1,3-butadiene in the presence of phosphazene bases (t-BuP4, t-BuP2 and t-BuP1), in benzene at room temperature, was studied. When t-BuP1 was used, the polymerization proceeded in a controlled manner, whereas the obtained homopolymers exhibited the desired molecular [...] Read more.

The anionic polymerization of styrene and 1,3-butadiene in the presence of phosphazene bases (t-BuP4, t-BuP2 and t-BuP1), in benzene at room temperature, was studied. When t-BuP1 was used, the polymerization proceeded in a controlled manner, whereas the obtained homopolymers exhibited the desired molecular weights and narrow polydispersity (Ð < 1.05). In the case of t-BuP2, homopolymers with higher than the theoretical molecular weights and relatively low polydispersity were obtained. On the other hand, in the presence of t-BuP4, the polymerization of styrene was uncontrolled due to the high reactivity of the formed carbanion. The kinetic studies from the polymerization of both monomers showed that the reaction rate follows the order of [t-BuP4]/[sec-BuLi] >>> [t-BuP2]/[sec-BuLi] >> [t-BuP1]/[sec-BuLi] > sec-BuLi. Furthermore, the addition of t-BuP2 and t-BuP1 prior the polymerization of 1,3-butadiene allowed the synthesis of polybutadiene with a high 1,2-microstructure (~45 wt %), due to the delocalization of the negative charge. Finally, the one pot synthesis of well-defined polyester-based copolymers [PS-b-PCL and PS-b-PLLA, PS: Polystyrene, PCL: Poly(ε-caprolactone) and PLLA: Poly(L-lactide)], with predictable molecular weights and a narrow molecular weight distribution (Ð < 1.2), was achieved by sequential copolymerization in the presence of t-BuP2 and t-BuP1. Full article

(This article belongs to the Special Issue Living Polymerization)

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21 pages, 4112 KiB

Open AccessArticle

Optimisation of Surface-Initiated Photoiniferter-Mediated Polymerisation under Confinement, and the Formation of Block Copolymers in Mesoporous Films

by Jessica C. Tom¹

, Robert Brilmayer¹, Johannes Schmidt² and Annette Andrieu-Brunsen^1,*

¹ Ernst-Berl Institut für Technische und Makromolekulare Chemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany

² Technische Universität Berlin, Fakultät II, Institut für Chemie, Hardenbergstr. 40, 10623 Berlin, Germany

Polymers 2017, 9(10), 539; https://doi.org/10.3390/polym9100539 - 23 Oct 2017

Cited by 25 | Viewed by 8890

Abstract

Nature as the ultimate inspiration can direct, gate, and selectively transport species across channels to fulfil a specific targeted function. Harnessing such precision over local structure and functionality at the nanoscale is expected to lead to indispensable developments in synthetic channels for application [...] Read more.

Nature as the ultimate inspiration can direct, gate, and selectively transport species across channels to fulfil a specific targeted function. Harnessing such precision over local structure and functionality at the nanoscale is expected to lead to indispensable developments in synthetic channels for application in catalysis, filtration and sensing, and in drug delivery. By combining mesoporous materials with localised charge-switchable poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, precisely controlling pore filling and exploring the possibility of incorporating two different responsive polymers, we hope to approach the precision control of natural systems in the absence of an external force. Here, we report a simple one-step approach to prepare a mesoporous silica thin film with ~8 nm pores functionalised with a photoiniferter by combining sol–gel chemistry and evaporation-induced self-assembly (EISA). We show that surface-initiated photoiniferter-mediated polymerisation (SI-PIMP) allows the incorporation of a high polymer content up to geometrical pore blocking by the simple application of UV light in the presence of a monomer and solvent, proceeding in a controlled manner in pore sizes below 10 nm, with the potential to tune the material properties through the formation of surface-grafted block copolymers. Full article

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

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16 pages, 2266 KiB

Open AccessArticle

Arborescent Unimolecular Micelles: Poly(γ-Benzyl l-Glutamate) Core Grafted with a Hydrophilic Shell by Copper(I)-Catalyzed Azide–Alkyne Cycloaddition Coupling

by Mario Gauthier^* and Greg Whitton

Department of Chemistry, Institute for Polymer Research and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada

Polymers 2017, 9(10), 540; https://doi.org/10.3390/polym9100540 - 23 Oct 2017

Cited by 4 | Viewed by 5282

Abstract

Amphiphilic copolymers were obtained by grafting azide-terminated polyglycidol, poly(ethylene oxide), or poly(2-hydroxyethyl acrylate) chain segments onto alkyne-functionalized arborescent poly(γ-benzyl l-glutamate) (PBG) cores of generations G1–G3 via copper(I)-catalyzed azide–alkyne Huisgen cycloaddition (CuAAC) coupling. The alkyne functional groups on the arborescent PBG substrates were [...] Read more.

Amphiphilic copolymers were obtained by grafting azide-terminated polyglycidol, poly(ethylene oxide), or poly(2-hydroxyethyl acrylate) chain segments onto alkyne-functionalized arborescent poly(γ-benzyl l-glutamate) (PBG) cores of generations G1–G3 via copper(I)-catalyzed azide–alkyne Huisgen cycloaddition (CuAAC) coupling. The alkyne functional groups on the arborescent PBG substrates were either distributed randomly or located exclusively at the end of the chains added in the last grafting cycle of the core synthesis. The location of these coupling sites influenced the ability of the arborescent copolymers to form unimolecular micelles in aqueous environments: The chain end grafting approach provided enhanced dispersibility in aqueous media and favored the formation of unimolecular micelles in comparison to random grafting. This is attributed to a better defined core-shell morphology for the copolymers with end-grafted shell segments. Aqueous solubility also depended on the type of material used for the shell chains. Coupling by CuAAC opens up possibilities for grafting a broad range of polymers on the arborescent substrates under mild conditions. Full article

(This article belongs to the Special Issue From Amphiphilic to Polyphilic Polymers)

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13 pages, 3849 KiB

Open AccessArticle

Preparation and Evaluation of Green Composites from Microcrystalline Cellulose and a Soybean-Oil Derivative

by Wendi Liu, Ming-en Fei, Yang Ban, Anming Jia and Renhui Qiu^*

College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China

Polymers 2017, 9(10), 541; https://doi.org/10.3390/polym9100541 - 23 Oct 2017

Cited by 54 | Viewed by 7617

Abstract

The present work aimed at developing fully green composites from renewable materials, i.e., acrylated epoxidized soybean oil (AESO) and microcrystalline cellulose (MCC) by a solution casting method. The reinforcing effect of MCC on AESO resins was optimized by adjusting MCC loading from 20 [...] Read more.

The present work aimed at developing fully green composites from renewable materials, i.e., acrylated epoxidized soybean oil (AESO) and microcrystalline cellulose (MCC) by a solution casting method. The reinforcing effect of MCC on AESO resins was optimized by adjusting MCC loading from 20 to 40 wt % in terms of physical, mechanical, and thermal properties as well as water absorption of the resulting MCC/AESO composites. The interaction between MCC and AESO was characterized by Fourier transform infrared (FTIR) analysis, which revealed possible hydrogen bonds between the –OH groups of MCC along with the polar components of AESO including C=O, –OH, and epoxy groups. This was further evidenced by a benign interfacial adhesion between MCC and AESO resins as revealed by scanning electron microscope (SEM) analysis. The incorporation of MCC into AESO resins significantly increased the density, hardness, flexural strength, and flexural modulus of the MCC/AESO composites, indicative of a significant reinforcing effect of MCC on AESO resins. The composite with 30 wt % MCC obtained the highest physical and mechanical properties due to the good dispersion and interfacial interaction between MCC and AESO matrix; the density, hardness, flexural strength, and flexural modulus of the composite were 15.7%, 25.0%, 57.2%, and 129.7% higher than those of pure AESO resin, respectively. However, the water resistance at room temperature and 100 °C of the composites were dramatically decreased due to the inherent hydrophilicity of MCC. Full article

(This article belongs to the Collection Polysaccharides)

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20 pages, 8840 KiB

Open AccessArticle

Novel Polyamides with 5H-Dibenzo[b,f]azepin-5-yl-Substituted Triphenylamine: Synthesis and Visible-NIR Electrochromic Properties

by Qingyi Lu¹, Wanan Cai¹, Haijun Niu^1,*, Wen Wang^2,*, Xuduo Bai¹ and Yanjun Hou¹

¹ Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Department of Macromolecular Science and Engineering, School of Chemical, Chemical Engineering and Materials, Heilongjiang University, Harbin 150086, China

² School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150080, China

Polymers 2017, 9(10), 542; https://doi.org/10.3390/polym9100542 - 23 Oct 2017

Cited by 11 | Viewed by 5692

Abstract

In this study, a new diamine monomer, namely 4,4′-diamino-4″-(5H-dibenzo[b,f]azepin-5-yl)triphenylamine, was prepared and polymerized with four kinds of dicarboxylic acids via direct polycondensation reaction resulting in a novel series of soluble and electroactive polyamides (PAs). The tough thin films of [...] Read more.

In this study, a new diamine monomer, namely 4,4′-diamino-4″-(5H-dibenzo[b,f]azepin-5-yl)triphenylamine, was prepared and polymerized with four kinds of dicarboxylic acids via direct polycondensation reaction resulting in a novel series of soluble and electroactive polyamides (PAs). The tough thin films of all PAs could be solution-cast onto an indium-tin oxide (ITO)-coated glass substrate owing to the good solubility in polar organic solvents. Two pairs of obvious redox peaks for these films were observed in cyclic voltammetry (CV) with low onset potentials (E_onset) of 0.37–0.42 V accompanying with remarkable reversible color changes between light yellow and dark blue. A new absorption peak at around 915 nm emerged in near infrared (NIR) spectra; the increasing potential indicated that PAs could be used as a NIR electrochromic material. Moreover, the PAs showed high coloration efficiency (CE; η) in the range of 190–259 cm² C⁻¹. Full article

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

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15 pages, 6809 KiB

Open AccessArticle

Poly(tris(4-carbazoyl-9-ylphenyl)amine)/Three Poly(3,4-ethylenedioxythiophene) Derivatives in Complementary High-Contrast Electrochromic Devices

by Chung-Wen Kuo¹, Jeng-Kuei Chang², Yuan-Chung Lin³, Tzi-Yi Wu^4,*

, Po-Ying Lee¹ and Tsung-Han Ho¹

¹ Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

² Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan

³ Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan

⁴ Department of Chemical Engineering and Materials Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan

Polymers 2017, 9(10), 543; https://doi.org/10.3390/polym9100543 - 23 Oct 2017

Cited by 18 | Viewed by 5896

Abstract

A carbazole-based polymer (poly(tris(4-carbazoyl-9-ylphenyl)amine) (PtCz)) is electrosynthesized on an indium tin oxide (ITO) electrode. PtCz film displays light yellow at 0.0 V, earthy yellow at 1.3 V, grey at 1.5 V, and dark grey at 1.8 V in 0.2 M LiClO₄/ACN/DCM [...] Read more.

A carbazole-based polymer (poly(tris(4-carbazoyl-9-ylphenyl)amine) (PtCz)) is electrosynthesized on an indium tin oxide (ITO) electrode. PtCz film displays light yellow at 0.0 V, earthy yellow at 1.3 V, grey at 1.5 V, and dark grey at 1.8 V in 0.2 M LiClO₄/ACN/DCM (ACN/DCM = 1:3, by volume) solution. The ΔT and coloration efficiency (η) of PtCz film are 30.5% and 54.8 cm²∙C⁻¹, respectively, in a solution state. Three dual-type electrochromic devices (ECDs) are fabricated using the PtCz as the anodic layer, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,3-dimethyl-3,4-dihydro-thieno[3,4-b][1,4]dioxepine) (PProDOT-Me₂), and poly(3,4-(2,2-diethylpropylenedioxy)thiophene) (PProDOT-Et₂) as the cathodic layers. PtCz/PProDOT-Me₂ ECD shows high ΔT_max (36%), high η_max (343.4 cm²·C⁻¹), and fast switching speed (0.2 s) at 572 nm. In addition, PtCz/PEDOT, PtCz/PProDOT-Me₂, and PtCz/PProDOT-Et₂ ECDs show satisfactory open circuit memory and long-term stability. Full article

(This article belongs to the Special Issue Polymer Characterization)

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14 pages, 8088 KiB

Open AccessArticle

Facile Synthesis of Polyaniline Nanotubes Using Self-Assembly Method Based on the Hydrogen Bonding: Mechanism and Application in Gas Sensing

by Changqing Yin^1,2,†, Lei Gao^1,†, Fei Zhou¹ and Guotao Duan^1,2,*

¹ Key Lab of Materials Physics, Anhui Key Lab of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China

² School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China

^† These authors contributed equally to this work.

Polymers 2017, 9(10), 544; https://doi.org/10.3390/polym9100544 - 24 Oct 2017

Cited by 30 | Viewed by 9431

Abstract

Based on hydrogen bonding, the highly uniform polyaniline (PANI) nanotubes were synthesized by self-assembly method using citric acid (CA) as the dopant and the structure-directing agent by optimizing the molar ratio of CA to aniline monomer (Ani). Synthesis conditions like reaction temperature and [...] Read more.

Based on hydrogen bonding, the highly uniform polyaniline (PANI) nanotubes were synthesized by self-assembly method using citric acid (CA) as the dopant and the structure-directing agent by optimizing the molar ratio of CA to aniline monomer (Ani). Synthesis conditions like reaction temperature and mechanical stirring were considered to explore the effects of hydrogen bonding on the morphologies. The effects of CA on the final morphology of the products were also investigated. The as-synthesized CA doped polyaniline (PANI) nanomaterials were further deposited on the plate electrodes for the test of gas sensing performance to ammonia (NH₃). The sensitivity to various concentrations of NH₃, the repeatability, and the stability of the sensors were also tested and analyzed. As a result, it was found that the PANI nanomaterial synthesized at the CA/Ani molar ratio of 0.5 has highly uniform tubular morphology and shows the best sensing performance to NH₃. It makes the PANI nanotubes a promising material for high performance gas sensing to NH₃. Full article

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

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8 pages, 1921 KiB

Open AccessArticle

Surface and Protein Adsorption Properties of 316L Stainless Steel Modified with Polycaprolactone Film

by Shih-Hang Chang^*

and Yuan-Chien Hsiao

Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan

Polymers 2017, 9(10), 545; https://doi.org/10.3390/polym9100545 - 23 Oct 2017

Cited by 17 | Viewed by 5668

Abstract

The surface and protein adsorption properties of 316L stainless steel (316L SS) modified with polycaprolactone (PCL) films are systematically investigated. The wettability of the PCL films was comparable to that of bare 316L SS because the rough surface morphology of the PCL films [...] Read more.

The surface and protein adsorption properties of 316L stainless steel (316L SS) modified with polycaprolactone (PCL) films are systematically investigated. The wettability of the PCL films was comparable to that of bare 316L SS because the rough surface morphology of the PCL films counteracts their hydrophobicity. Surface modification with PCL film significantly improves the corrosion resistance of the 316L SS because PCL is insulating in nature. A coating of PCL film effectively reduces the amount of adhered bovine serum albumin (BSA) on the surface of 316L SS in a bicinchoninic acid protein assay. PCL is both biodegradable and biocompatible, suggesting the potential for the surface modification of implants used in human bodies; in these applications, excellent corrosion resistance and anticoagulant properties are necessary. Full article

(This article belongs to the Special Issue Surface Modification and Functional Coatings for Polymers)

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13 pages, 2594 KiB

Open AccessArticle

Preparation and Evaluation of Core–Shell Magnetic Molecularly Imprinted Polymers for Solid-Phase Extraction and Determination of Sterigmatocystin in Food

by Jing-Min Liu^1,2, Shu-Yuan Wei³, Hui-Lin Liu¹, Guo-Zhen Fang³ and Shuo Wang^1,2,*

¹ Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology & Business University (BTBU), Beijing 100048, China

² Research Center of Food Science and Human Health, School of Medicine, Nankai University, Tianjin 300071, China

³ Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China

Polymers 2017, 9(10), 546; https://doi.org/10.3390/polym9100546 - 23 Oct 2017

Cited by 28 | Viewed by 5565

Abstract

Magnetic molecularly imprinted polymers (MMIPs), combination of outstanding magnetism with specific selective binding capability for target molecules, have proven to be attractive in separation science and bio-applications. Herein, we proposed the core–shell magnetic molecularly imprinted polymers for food analysis, employing the Fe₃ [...] Read more.

Magnetic molecularly imprinted polymers (MMIPs), combination of outstanding magnetism with specific selective binding capability for target molecules, have proven to be attractive in separation science and bio-applications. Herein, we proposed the core–shell magnetic molecularly imprinted polymers for food analysis, employing the Fe₃O₄ particles prepared by co-precipitation protocol as the magnetic core and MMIP film onto the silica layer as the recognition and adsorption of target analytes. The obtained MMIPs materials have been fully characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), vibrating sample magnetometer (VSM), and re-binding experiments. Under the optimal conditions, the fabricated Fe₃O₄@MIPs demonstrated fast adsorption equilibrium, a highly improved imprinting capacity, and excellent specificity to target sterigmatocystin (ST), which have been successfully applied as highly efficient solid-phase extraction materials followed by high-performance liquid chromatography (HPLC) analysis. The MMIP-based solid phase extraction (SPE) method gave linear response in the range of 0.05–5.0 mg·L⁻¹ with a detection limit of 9.1 µg·L⁻¹. Finally, the proposed method was used for the selective isolation and enrichment of ST in food samples with recoveries in the range 80.6–88.7% and the relative standard deviation (RSD) <5.6%. Full article

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39 pages, 19702 KiB

Open AccessArticle

Deformation-Induced Phase Transitions in iPP Polymorphs

by Harm J. M. Caelers^1,†, Enrico M. Troisi^1,†, Leon E. Govaert^1,2 and Gerrit W. M. Peters^1,*

¹ Department of Mechanical Engineering, Materials Technology Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

² Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

^† Current address: Sabic T&I, STC Geleen, P.O. Box 319, 6160 AH Geleen, The Netherlands.

Polymers 2017, 9(10), 547; https://doi.org/10.3390/polym9100547 - 24 Oct 2017

Cited by 26 | Viewed by 6307

Abstract

This detailed study reveals the relation between structural evolution and the mechanical response of

α

-,

β

- and

γ

-iPP. Uni-axial compression experiments, combined with in situ WAXD measurements, allowed for the identification of the evolution phenomena in terms of phase composition. [...] Read more.

This detailed study reveals the relation between structural evolution and the mechanical response of

α

-,

β

- and

γ

-iPP. Uni-axial compression experiments, combined with in situ WAXD measurements, allowed for the identification of the evolution phenomena in terms of phase composition. Tensile experiments in combination with SAXS revealed orientation and voiding phenomena, as well as structural evolution in the thickness of the lamellae and amorphous layers. On the level of the crystallographic unit cell, the WAXD experiments provided insight into the early stages of deformation. Moreover, transitions in the crystal phases taking place in the larger deformation range and the orientation of crystal planes were monitored. At all stretching temperatures, the crystallinity decreases upon deformation, and depending on the temperature, different new structures are formed. Stretching at low temperatures leads to crystal destruction and the formation of the oriented mesophase, independent of the initial polymorph. At high temperatures, above

T α_{c}

, all polymorphs transform into oriented

α

-iPP. Small quantities of the initial structures remain present in the material. The compression experiments, where localization phenomena are excluded, show that these transformations take place at similar strains for all polymorphs. For the post yield response, the strain hardening modulus is decisive for the mechanical behavior, as well as for the orientation of lamellae and the evolution of void fraction and dimensions.

β

-iPP shows by far the most intense voiding in the entire experimental temperature range. The macroscopic localization behavior and strain at which the transition from disk-like void shapes, oriented with the normal in tensile direction, into fibrillar structures takes place is directly correlated with the strain hardening modulus. Full article

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

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Polymers, Volume 9, Issue 10 (October 2017) – 86 articles

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