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Polymers, Volume 10, Issue 12 (December 2018)

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Open AccessArticle The Chemical Compatibility and Adhesion of Energetic Materials with Several Polymers and Binders: An Experimental Study
Polymers 2018, 10(12), 1396; https://doi.org/10.3390/polym10121396 (registering DOI)
Received: 15 November 2018 / Revised: 11 December 2018 / Accepted: 12 December 2018 / Published: 16 December 2018
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Abstract
The chemical compatibility and the adhesion of energetic materials and additive materials exert a strong influence on the sensitivity, safety and performance of a polymer-bonded explosive (PBX). In this study, the chemical compatibility of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN) with several polymers were
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The chemical compatibility and the adhesion of energetic materials and additive materials exert a strong influence on the sensitivity, safety and performance of a polymer-bonded explosive (PBX). In this study, the chemical compatibility of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN) with several polymers were evaluated using the vacuum stability test (VST) and the differential scanning calorimetry (DSC); while the adhesion between RDX or PETN and each binder based on these polymers was determined through interfacial characteristics using contact angle measurement. The experimental results demonstrate that RDX and PETN are compatible with polystyrene (PS), nitrocellulose (NC) and fluoroelastomer (FKM) according to the STANAG 4147. Therefore the two polymers can be used as adhesives in PBX composition. Moreover, based on interfacial characteristics such as interfacial tension and work of adhesion, the adhesion between RDX and each binder was predicted to be better than that of PETN. Full article
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Open AccessCommunication Fast Screening of Diol Impurities in Methoxy Poly(Ethylene Glycol)s (mPEG)s by Liquid Chromatography on Monolithic Silica Rods
Polymers 2018, 10(12), 1395; https://doi.org/10.3390/polym10121395 (registering DOI)
Received: 30 November 2018 / Revised: 11 December 2018 / Accepted: 11 December 2018 / Published: 16 December 2018
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Abstract
The determination of diol impurities in methoxy poly(ethylene glycol)s (mPEG)s is of high importance, e.g., in the area of pharmaceutical applications, since mPEGs are considered the gold standard—based on properties of biocompatibility, stealth effect against the immune system, and well-established procedures used in
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The determination of diol impurities in methoxy poly(ethylene glycol)s (mPEG)s is of high importance, e.g., in the area of pharmaceutical applications, since mPEGs are considered the gold standard—based on properties of biocompatibility, stealth effect against the immune system, and well-established procedures used in PEGylation reactions. Herein, we communicate a straightforward and fast approach for the resolution of the PEGdiol impurities in mPEG products by liquid chromatography on reversed-phase monolithic silica-rods. Thus, we utilize fine, in-house prepared and narrow dispersity mPEGs (Ð ≤ 1.1) and commercial PEGdiol standards as a reference. Most efficient analysis of diol impurities becomes possible with reversed-phase liquid chromatography that results in selective elution of the PEGdiol from mPEG macromolecule populations in partition/adsorption mode. We do this by a minimum selectivity of the population of macromolecules characterizing the narrow molar mass distributions of mPEG. Control experiments with intentionally added water at the start of the well-controlled mPEG synthesis via the living anionic ring opening polymerization of ethylene oxide clearly reconciled the existence of PEGdiol impurity in chromatographed samples. The here-demonstrated methodology allows for the resolution of diol impurities of less than one percent in elution times of only a few minutes, confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of the collected elution fractions. The unique combination of the open flow-through pore structure of the monolithic silica rods and resultant varying accessibility of C18-derivatized pore surfaces indicates beneficial properties for robust and end-group-specific adsorption/partition liquid chromatography of synthetic macromolecules. Full article
(This article belongs to the Special Issue Hydrophilic Polymers)
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Open AccessArticle Confined Polymers as Self-Avoiding Random Walks on Restricted Lattices
Polymers 2018, 10(12), 1394; https://doi.org/10.3390/polym10121394 (registering DOI)
Received: 3 November 2018 / Revised: 2 December 2018 / Accepted: 11 December 2018 / Published: 15 December 2018
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Abstract
Polymers in highly confined geometries can display complex morphologies including ordered phases. A basic component of a theoretical analysis of their phase behavior in confined geometries is the knowledge of the number of possible single-chain conformations compatible with the geometrical restrictions and the
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Polymers in highly confined geometries can display complex morphologies including ordered phases. A basic component of a theoretical analysis of their phase behavior in confined geometries is the knowledge of the number of possible single-chain conformations compatible with the geometrical restrictions and the established crystalline morphology. While the statistical properties of unrestricted self-avoiding random walks (SAWs) both on and off-lattice are very well known, the same is not true for SAWs in confined geometries. The purpose of this contribution is (a) to enumerate the number of SAWs on the simple cubic (SC) and face-centered cubic (FCC) lattices under confinement for moderate SAW lengths, and (b) to obtain an approximate expression for their behavior as a function of chain length, type of lattice, and degree of confinement. This information is an essential requirement for the understanding and prediction of entropy-driven phase transitions of model polymer chains under confinement. In addition, a simple geometric argument is presented that explains, to first order, the dependence of the number of restricted SAWs on the type of SAW origin. Full article
(This article belongs to the Special Issue Simulations of Polymers)
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Open AccessArticle Novel Polymer Material for Efficiently Removing Methylene Blue, Cu(II) and Emulsified Oil Droplets from Water Simultaneously
Polymers 2018, 10(12), 1393; https://doi.org/10.3390/polym10121393 (registering DOI)
Received: 18 November 2018 / Revised: 9 December 2018 / Accepted: 14 December 2018 / Published: 15 December 2018
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Abstract
The pollution of water resources has become a worldwide concern. The primary pollutants including insoluble oil, toxic dyes, and heavy metal ions. Herein, we report a polymer adsorbent, named SPCT, to remove the above three contaminants from water simultaneously. The preparation process of
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The pollution of water resources has become a worldwide concern. The primary pollutants including insoluble oil, toxic dyes, and heavy metal ions. Herein, we report a polymer adsorbent, named SPCT, to remove the above three contaminants from water simultaneously. The preparation process of SPCT contains two steps. Firstly, a hydrogel composed of sulfonated phenolic resin (SMP) and polyethyleneimine (PEI) was synthesized using glutaraldehyde (GA) as the crosslinking agent, and the product was named SPG. Then SPCT was prepared by the reaction between SPG and citric acid (CA) at 170 C. SPCT exhibited an excellent performance for the removal of methylene blue (MB) and Cu(II) from aqueous solution. For a solution with a pollutant concentration of 50 mg L−1, a removal efficiency of above 90% could be obtained with a SPCT dosage of 0.2 g L−1 for MB, or a SPCT dosage of 0.5 g L−1 for Cu(II), respectively. SPCT also presented an interesting wettability. In air, it was both superhydrophilic and superoleophilic, and it was superoleophobic underwater. Therefore, SPCT could successfully separate oil-in-water emulsion with high separation efficiency and resistance to oil fouling. Additionally, SPCT was easily regenerated by using dilute HCl solution as an eluent. The outstanding performance of SPCT and the efficient, cost-effective preparation process highlight its potential for practical applications. Full article
(This article belongs to the Special Issue Polymer for Separation)
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Open AccessArticle Self-Healing Cellulose Nanocrystals-Containing Gels via Reshuffling of Thiuram Disulfide Bonds
Polymers 2018, 10(12), 1392; https://doi.org/10.3390/polym10121392 (registering DOI)
Received: 16 November 2018 / Revised: 12 December 2018 / Accepted: 12 December 2018 / Published: 15 December 2018
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Abstract
Self-healing gels based on reshuffling disulfide bonds have attracted great attention due to their ability to restore structure and mechanical properties after damage. In this work, self-healing gels with different cellulose nanocrystals (CNC) contents were prepared by embedding the thiuram disulfide bonds into
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Self-healing gels based on reshuffling disulfide bonds have attracted great attention due to their ability to restore structure and mechanical properties after damage. In this work, self-healing gels with different cellulose nanocrystals (CNC) contents were prepared by embedding the thiuram disulfide bonds into gels via polyaddition. By the reshuffling of thiuram disulfide bonds, the CNC-containing gels repair the crack and recover mechanical properties rapidly under visible light in air. The thiuram disulfide-functionalized gels with a CNC content of 2.2% are highly stretchable and can be stretched approximately 42.6 times of their original length. Our results provide useful approaches for the preparation of dynamic CNC-containing gels with implications in many related engineering applications. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
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Open AccessArticle Effect of Chemical Modification on Mechanical Properties of Wood-Plastic Composite Injection-Molded Parts
Polymers 2018, 10(12), 1391; https://doi.org/10.3390/polym10121391 (registering DOI)
Received: 1 November 2018 / Revised: 12 December 2018 / Accepted: 13 December 2018 / Published: 15 December 2018
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Abstract
Wood chips from furniture-manufacturing byproducts, which do not include adhesive or paint in the waste wood, were used for the flouring process and chemical modification of wood flour (WF). After chemical modification, the WF was mixed with polypropylene through extrusion compounding and injection-molding
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Wood chips from furniture-manufacturing byproducts, which do not include adhesive or paint in the waste wood, were used for the flouring process and chemical modification of wood flour (WF). After chemical modification, the WF was mixed with polypropylene through extrusion compounding and injection-molding to prepare wood-plastic composite (WPC) injection-molded specimens for the American Society for Testing and Materials. Static contact angle measurements and stereomicroscope observations were performed. In this study, it was confirmed that the impact strength was improved by up to 55.8% and the tensile strength by up to 33.8%. The flexural modulus decreased marginally. As a result of WF chemical modification, the measured contact angle of WPC increased, which means that the wettability of the WPC specimen surface decreased. In addition, it was observed through stereomicroscopy that the whitening of the surface of the WPC specimen improved. Full article
(This article belongs to the Special Issue Modification of Natural Fibres to Improve Biocomposites Performances)
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Open AccessArticle Microdrilling of Through-Holes in Flexible Printed Circuits using Picosecond Ultrashort Pulse Laser
Polymers 2018, 10(12), 1390; https://doi.org/10.3390/polym10121390 (registering DOI)
Received: 5 October 2018 / Revised: 22 November 2018 / Accepted: 11 December 2018 / Published: 14 December 2018
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Abstract
High density and high quality interconnects are necessary for the preparation of miniaturized and lightweight electronic products. Therefore, small-diameter and high-density through-holes in FPCs (Flexible Printed Circuits) are required. However, the current processing methods cannot further decrease the diameters and improve the quality
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High density and high quality interconnects are necessary for the preparation of miniaturized and lightweight electronic products. Therefore, small-diameter and high-density through-holes in FPCs (Flexible Printed Circuits) are required. However, the current processing methods cannot further decrease the diameters and improve the quality of through-holes. Comparatively, ultrashort pulse laser is a good choice. In this paper, the processing technology for the microdrilling of through-holes in FPCs using a 10 ps pulse laser was systematically studied. The effects of laser parameters, including the wavelength, energy, pulses and polarization, on the drilling of through-holes were investigated. The various processing parameters were optimized and the plausible reasons were discussed. Finally, the desired small-diameter and high-density through-holes in FPCs were obtained. The experimental results showed that, through-holes with diameters of less than 10 µm and inlet interconnection pitches of 0 ~ 2 µm could be successfully drilled in FPCs using ultrashort pulse laser. Full article
(This article belongs to the Special Issue Laser processing in polymer research)
Open AccessArticle Synthesis and Characterization of a Molecularly Imprinted Polymer of Spermidine and the Exploration of Its Molecular Recognition Properties
Polymers 2018, 10(12), 1389; https://doi.org/10.3390/polym10121389 (registering DOI)
Received: 27 October 2018 / Revised: 8 December 2018 / Accepted: 12 December 2018 / Published: 14 December 2018
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Abstract
Spermidine is a functional ingredient that can extend the lifespan of many foods and indicate meat safety. However, its synthesis and enrichment is expensive and complex. To develop an effective separation material that can offer highly selective recognition of spermidine, we first applied
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Spermidine is a functional ingredient that can extend the lifespan of many foods and indicate meat safety. However, its synthesis and enrichment is expensive and complex. To develop an effective separation material that can offer highly selective recognition of spermidine, we first applied non-covalent molecular imprinting technology using methacrylic acid as a functional monomer, azobisisobutyronitrile as an initiator, and ethylene glycol dimethacrylate as a cross-linker. The adsorption properties of the polymers were analyzed using the Scatchard equation, the Lagergren kinetic equation, and the static distribution coefficient. The optimal polymerization molar ratio of the template molecule spermidine to the functional monomer was 1:4, the maximum adsorption amount was 97.75 μmol/g, and the adsorption equilibrium time was 300 min. The selective experiment showed that the interfering substances tyramine and histamine had selectivity factor α values of 2.01 and 1.78, respectively, indicating that the prepared polymer had good spermidine recognition ability. The density function theory calculations showed that the hydrogen bond strength, steric effect, and product energy caused adsorption and separation differences among the different imprinted polymer complexes. Full article
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Open AccessArticle Preparation of Pt-Catalyst by Poly(p-phenylenediamine) Nanocomposites Assisted by Microwave Radiation for Proton Exchange Membrane Fuel Cell
Polymers 2018, 10(12), 1388; https://doi.org/10.3390/polym10121388 (registering DOI)
Received: 19 November 2018 / Accepted: 12 December 2018 / Published: 14 December 2018
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Abstract
The Pt elements are prepared via the redox reaction with microwave (MW) irradiation in the presence of poly(p-phenylenediamine) (PpPD) which is polymerized on XC72 carbon matrix (PpPD/XC72), behaving as reducing agent. The free primary amines of PpPD are actually converted (oxidized) to secondary
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The Pt elements are prepared via the redox reaction with microwave (MW) irradiation in the presence of poly(p-phenylenediamine) (PpPD) which is polymerized on XC72 carbon matrix (PpPD/XC72), behaving as reducing agent. The free primary amines of PpPD are actually converted (oxidized) to secondary ones (5,10-dihydrophenazine) after MW irradiation. Transmission electronic microscopy (TEM) micrographs reveal the prepared Pt nanoparticles are well-dispersed on the carbon matrix like commercial Pt-implanted carbon nanocomposite (Pt/C). From the residue weights of thermogravimetric analysis (TGA) thermograms of Pt-loaded PpPD/XC72 (PpPD/XC72-Pt-MW), more Pt (18.49 wt %) nanoparticles are implanted on PpPD/XC72 composite. The Pt-implanted wt % on PpPD/XC72 matrix is just slightly lower than that of commercial Pt/C (22.30 wt %). The Pt-catalyst supports of PpPD/XC72-Pt-MW illustrate typical cyclic voltammograms (C-V) of Pt-catalyst, including significant Pt–H oxidation and Pt–O reduction peaks. The electrochemical active surface area of PpPD/XC72-Pt-MW is found to be as high as 60.1 m2 g-1. Max. number of electron transfer during oxygen reduction reaction (ORR) approaches 3.83 for PpPD/XC72-Pt-MW, higher than that of commercial Pt/C (3.62). Single cell based on PpPD/XC72-Pt-MW demonstrates much higher specific max. power density to be 34.6 mW cm-2 Pt, higher than that single cell prepared with commercial Pt/C electrode (30.6 mW cm-2 Pt). Full article
(This article belongs to the Special Issue Polymeric Materials for Electrochemical Energy Conversion and Storage)
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Open AccessArticle Electrospun Polycaprolactone Nanofibers as a Reaction Membrane for Lateral Flow Assay
Polymers 2018, 10(12), 1387; https://doi.org/10.3390/polym10121387
Received: 18 November 2018 / Revised: 5 December 2018 / Accepted: 10 December 2018 / Published: 14 December 2018
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Abstract
Electrospun polycaprolactone (PCL) nanofibers have emerged as a promising material in diverse biomedical applications due to their various favorable features. However, their application in the field of biosensors such as point-of-care lateral flow assays (LFA) has not been investigated. The present study demonstrates
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Electrospun polycaprolactone (PCL) nanofibers have emerged as a promising material in diverse biomedical applications due to their various favorable features. However, their application in the field of biosensors such as point-of-care lateral flow assays (LFA) has not been investigated. The present study demonstrates the use of electrospun PCL nanofibers as a reaction membrane for LFA. Electrospun PCL nanofibers were treated with NaOH solution for different concentrations and durations to achieve a desirable flow rate and optimum detection sensitivity in nucleic acid-based LFA. It was observed that the concentration of NaOH does not affect the physical properties of nanofibers, including average fiber diameter, average pore size and porosity. However, interestingly, a significant reduction of the water contact angle was observed due to the generation of hydroxyl and carboxyl groups on the nanofibers, which increased their hydrophilicity. The optimally treated nanofibers were able to detect synthetic Zika viral DNA (as a model analyte) sensitively with a detection limit of 0.5 nM. Collectively, the benefits such as low-cost of fabrication, ease of modification, porous nanofibrous structures and tunability of flow rate make PCL nanofibers a versatile alternative to nitrocellulose membrane in LFA applications. This material offers tremendous potential for a broad range of point-of-care applications. Full article
(This article belongs to the Special Issue Nanotechnology of Polymers and Biomaterials)
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Open AccessArticle Process Evaluation of the Metal-Organic Frameworks for the Application of Personal Protective Equipment with Filtration Function
Polymers 2018, 10(12), 1386; https://doi.org/10.3390/polym10121386
Received: 29 November 2018 / Revised: 11 December 2018 / Accepted: 12 December 2018 / Published: 14 December 2018
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Abstract
Metal-organic frameworks (MOFs) have been regarded as an ideal material for the development of functional textiles with filtration function. Such functional textiles with filtration function can be further used to develop personal protective equipment, such as protective masks. This paper focuses on the
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Metal-organic frameworks (MOFs) have been regarded as an ideal material for the development of functional textiles with filtration function. Such functional textiles with filtration function can be further used to develop personal protective equipment, such as protective masks. This paper focuses on the comparisons of different processes when applying MOFs to conventional textiles. Two different processes existing in the literature, namely the electrospinning method and hot-pressing method, are discussed in this paper. Materials loaded with MOFs developed with these two processes are evaluated and compared, regarding the adsorption of dyes in water and the removal of pollutants. Experiment results indicate that the hot-pressing method is more advantageous when applying MOF to textiles, in terms of adsorption and removal efficiency. Full article
(This article belongs to the Special Issue Polymer Processing for Enhancing Textile Application)
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Open AccessArticle Facile Fabrication of Multi-Structured SiO2@PVDF-HFP Nanofibrous Membranes for Enhanced Copper Ions Adsorption
Polymers 2018, 10(12), 1385; https://doi.org/10.3390/polym10121385
Received: 28 November 2018 / Revised: 10 December 2018 / Accepted: 11 December 2018 / Published: 13 December 2018
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Abstract
The low-cost, heavy metal ion (Cu(II)) adsorptive multi-structured nanofibrous membranes of silicon oxide naonoparticles in-situ anchored polyvinylidene fluoride-hexafluoropropylene (SiO2@PVDF-HFP) fibers were fabricated by the facile electrospinning technique combined with sol–gel strategy. To explore the benefits of the structure-related Cu(II) adsorption capacity,
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The low-cost, heavy metal ion (Cu(II)) adsorptive multi-structured nanofibrous membranes of silicon oxide naonoparticles in-situ anchored polyvinylidene fluoride-hexafluoropropylene (SiO2@PVDF-HFP) fibers were fabricated by the facile electrospinning technique combined with sol–gel strategy. To explore the benefits of the structure-related Cu(II) adsorption capacity, the fiber diameters of SiO2@PVDF-HFP nanofibrous membranes were changed which also resulted in the change of their porosity. Taking advantage of the constructed multi-structures and efficient fiber morphology regulation which not only changed the PVDF-HFP nanofibrous membrane from hydrophobic to superhydrophilic but also increased the porosity of the membrane, the SiO2@PVDF-HFP nanofibrous membrane with a smaller diameter and a larger porosity exhibits higher Cu(II) adsorption capacity. The adsorption amount was approximate to 21.9 mg per gram of the membrane, which was higher than that of membranes with larger fiber diameter (smaller porosity) and the smooth one. Furthermore, the model isotherms of Freundlich and Langmuir, as well as the kinetic models of pseudo-first-order and pseudo-second-order were preferred to analyze the adsorption equilibrium data. The Freundlich model and the pseudo-first-order were well fitted to the adsorption experimental data. It not only uncovers the structure-related-property of multi-structured nanofibrous membranes, but also provides an efficient and facile way to design heavy metal ion adsorption materials. Full article
(This article belongs to the Special Issue Multi-functional Polymer Composites and Structures)
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Open AccessArticle Single Local Injection of Epigallocatechin Gallate-Modified Gelatin Attenuates Bone Resorption and Orthodontic Tooth Movement in Mice
Polymers 2018, 10(12), 1384; https://doi.org/10.3390/polym10121384
Received: 12 November 2018 / Revised: 3 December 2018 / Accepted: 5 December 2018 / Published: 13 December 2018
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Abstract
Osteoclastic bone resorption enables orthodontic tooth movement (OTM) in orthodontic treatment. Previously, we demonstrated that local epigallocatechin gallate (EGCG) injection successfully slowed the rate of OTM; however, repeat injections were required. In the present study, we produced a liquid form of EGCG-modified gelatin
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Osteoclastic bone resorption enables orthodontic tooth movement (OTM) in orthodontic treatment. Previously, we demonstrated that local epigallocatechin gallate (EGCG) injection successfully slowed the rate of OTM; however, repeat injections were required. In the present study, we produced a liquid form of EGCG-modified gelatin (EGCG-GL) and examined the properties of EGCG-GL with respect to prolonging EGCG release, NF-E2-related factor 2 (Nrf2) activation, osteoclastogenesis inhibition, bone destruction, and OTM. We found EGCG-GL both prolonged the release of EGCG and induced the expression of antioxidant enzyme genes, such as heme oxygenase 1 (Hmox1) and glutamate-cysteine ligase (Gclc), in the mouse macrophage cell line, RAW264.7. EGCG-GL attenuated intracellular reactive oxygen species (ROS) levels were induced by the receptor activator of nuclear factor-kB ligand (RANKL) and inhibited RANKL-mediated osteoclastogenesis in vitro. An animal model of bone destruction, induced by repeat Lipopolysaccharide (LPS)-injections into the calvaria of male BALB/c mice, revealed that a single injection of EGCG-GL on day-1 could successfully inhibit LPS-mediated bone destruction. Additionally, experimental OTM of maxillary first molars in male mice was attenuated by a single EGCG-GL injection on day-1. In conclusion, EGCG-GL prolongs the release of EGCG and inhibits osteoclastogenesis via the attenuation of intracellular ROS signaling through the increased expression of antioxidant enzymes. These results indicate EGCG-GL would be a beneficial therapeutic approach both in destructive bone disease and in controlling alveolar bone metabolism. Full article
(This article belongs to the Special Issue Synthesis and Application of Conjugated Polymers)
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Open AccessArticle Efficient Adsorption of Pb(II) from Aqueous Solutions by Metal Organic Framework (Zn-BDC) Coated Magnetic Montmorillonite
Polymers 2018, 10(12), 1383; https://doi.org/10.3390/polym10121383
Received: 29 November 2018 / Revised: 11 December 2018 / Accepted: 12 December 2018 / Published: 13 December 2018
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Abstract
Composite adsorption materials combine the advantages of various adsorptive materials and compensate for the defects of single adsorbents. Magnetic montmorillonite (MMMT) shows good adsorption properties for Pb(II). In order to further improve the adsorption properties of MMMT, in this work, Zn-BDC, a kind
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Composite adsorption materials combine the advantages of various adsorptive materials and compensate for the defects of single adsorbents. Magnetic montmorillonite (MMMT) shows good adsorption properties for Pb(II). In order to further improve the adsorption properties of MMMT, in this work, Zn-BDC, a kind of metal–organic framework (MOF), was modified onto the surface of MMMT by in situ polymerization. The composite material [email protected] was characterized by Zetasizer, SEM, TEM, FTIR, XRD, VSM, and XPS. The influence of adsorption conditions on the adsorption capacity of [email protected] for Pb(II) was examined, including the adsorbent dosage, pH of Pb(II) solution, initial concentration of Pb(II), and the temperature and adsorption time. Also, the adsorption mechanism was studied. The results of this study show that [email protected] adsorbs Pb(II) via chemisorption. In addition, [email protected] exhibits good potential for adsorbing Pb(II), including its high adsorption capacity (724.64 mg/g) and good recyclability. Full article
(This article belongs to the Special Issue Metal-Organic Frameworks)
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Open AccessArticle Microporous Materials Based on Norbornadiene-Based Cross-Linked Polymers
Polymers 2018, 10(12), 1382; https://doi.org/10.3390/polym10121382
Received: 8 November 2018 / Revised: 3 December 2018 / Accepted: 5 December 2018 / Published: 13 December 2018
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Abstract
New microporous homopolymers were readily prepared from norbornadiene-2,5, its dimer and trimer by addition (vinyl) polymerization of the corresponding monomers with 60–98% yields. As a catalyst Pd-N-heterocyclic carbene complex or Ni(II) 2-ethylhexanoate activated with Na+[B(3,5-(CF3)2C
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New microporous homopolymers were readily prepared from norbornadiene-2,5, its dimer and trimer by addition (vinyl) polymerization of the corresponding monomers with 60–98% yields. As a catalyst Pd-N-heterocyclic carbene complex or Ni(II) 2-ethylhexanoate activated with Na+[B(3,5-(CF3)2C6H3)4] or methylaluminoxane was used. The synthesized polynorbornenes are cross-linked and insoluble. They are glassy and amorphous polymers. Depending on the nature of the catalyst applied, BET surface areas were in the range of 420–970 m2/g. The polymers with the highest surface area were obtained in the presence of Pd-catalysts from the trimer of norbornadiene-2,5. The total pore volume of the polymers varies from 0.39 to 0.79 cm3/g, while the true volume of micropores was 0.14–0.16 cm3/g according to t-plot. These polymers gave CO2 uptake from 1.2 to 1.9 mmol/g at 273 K and 1 atm. The porous structure of new polymers was also studied by means of wide-angle X-ray diffraction and positron annihilation lifetime spectroscopy. Full article
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Open AccessArticle Solid-Phase Synthesis of Cellulose Acetate Butyrate as Microsphere Wall Materials for Sustained Release of Emamectin Benzoate
Polymers 2018, 10(12), 1381; https://doi.org/10.3390/polym10121381
Received: 13 November 2018 / Revised: 5 December 2018 / Accepted: 10 December 2018 / Published: 13 December 2018
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Abstract
Emamectin benzoate (EB), a widely used pesticide, is prone to decomposition by ultraviolet light and suffers from the corresponding loss of efficacy. The timed release of EB based on microspheres is one of the effective methods to solve this issue. As a non-toxic
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Emamectin benzoate (EB), a widely used pesticide, is prone to decomposition by ultraviolet light and suffers from the corresponding loss of efficacy. The timed release of EB based on microspheres is one of the effective methods to solve this issue. As a non-toxic cellulose ester, cellulose acetate butyrate (CAB) is regarded as one of the best wall-forming materials for microcapsules with a good controlled release performance. Herein, two methods—mechanical activation (MA) technology and a conventional liquid phase (LP) method—were employed to synthesize different CABs, namely CAB-MA and CAB-LP, respectively. The molecular structure, rheological property, and thermal stability of these CABs were investigated. The two CABs were used to prepare microspheres for the loading and release of EB via an o/w (oil-in-water) solvent evaporation method. Moreover, the performances such as drug loading, drug entrapment, and anti-photolysis of the drug for these microspheres were studied. The results showed that both CABs were available as wall materials for loading and releasing EB. Compared with CAB-LP, CAB-MA presented a lower molecular weight and a narrower molecular weight distribution. Moreover, the MA method endowed the CAB with more ester substituent groups and less crystalline structure in comparison to the LP method, which had benefits including pelletizing and drug loading. Full article
(This article belongs to the Special Issue Polymer-based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle Improvement of Adhesion Properties of Polyamide 6 and Polyoxymethylene-Copolymer by Atmospheric Cold Plasma Treatment
Polymers 2018, 10(12), 1380; https://doi.org/10.3390/polym10121380
Received: 8 November 2018 / Revised: 4 December 2018 / Accepted: 8 December 2018 / Published: 12 December 2018
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Abstract
A study is presented on cold plasma treatment of the surfaces of two engineering polymers, polyamide 6 (PA6) and polyoxymethylene (POM-C), by diffuse coplanar surface barrier discharges under atmospheric air conditions. We found that plasma treatment improved the adhesion of both polymers for
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A study is presented on cold plasma treatment of the surfaces of two engineering polymers, polyamide 6 (PA6) and polyoxymethylene (POM-C), by diffuse coplanar surface barrier discharges under atmospheric air conditions. We found that plasma treatment improved the adhesion of both polymers for either polymer/polymer or polymer/steel joints. However, the improved adhesion was selective for the investigated adhesive agents that were dissimilar for the two studied polymers. In addition, improvement was significantly higher for PA6 as compared to POM-C. The observed variation of the adhesion was discussed in terms of the changes in surface chemistry, wettability and topography of the polymer surface. Full article
(This article belongs to the Special Issue Plasma Processing in Polymers)
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Open AccessReview Implantable Polymeric Drug Delivery Devices: Classification, Manufacture, Materials, and Clinical Applications
Polymers 2018, 10(12), 1379; https://doi.org/10.3390/polym10121379
Received: 8 November 2018 / Accepted: 10 December 2018 / Published: 12 December 2018
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Abstract
The oral route is a popular and convenient means of drug delivery. However, despite its advantages, it also has challenges. Many drugs are not suitable for oral delivery due to: first pass metabolism; less than ideal properties; and side-effects of treatment. Additionally, oral
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The oral route is a popular and convenient means of drug delivery. However, despite its advantages, it also has challenges. Many drugs are not suitable for oral delivery due to: first pass metabolism; less than ideal properties; and side-effects of treatment. Additionally, oral delivery relies heavily on patient compliance. Implantable drug delivery devices are an alternative system that can achieve effective delivery with lower drug concentrations, and as a result, minimise side-effects whilst increasing patient compliance. This article gives an overview of classification of these drug delivery devices; the mechanism of drug release; the materials used for manufacture; the various methods of manufacture; and examples of clinical applications of implantable drug delivery devices. Full article
(This article belongs to the Special Issue Polymer-based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle Interface Modulation of Core-Shell Structured BaTiO3@polyaniline for Novel Dielectric Materials from Its Nanocomposite with Polyarylene Ether Nitrile
Polymers 2018, 10(12), 1378; https://doi.org/10.3390/polym10121378
Received: 8 October 2018 / Revised: 4 December 2018 / Accepted: 10 December 2018 / Published: 12 December 2018
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Abstract
The core-shell structured polyaniline-functionalized-BaTiO3 ([email protected]) nanoparticles with controllable shell layer thicknesses are developed via in-situ aniline polymerization technology and characterized in detail. The results prove that the PANI shell layer with the adjustable and controllable thicknesses of 3–10 nm are
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The core-shell structured polyaniline-functionalized-BaTiO3 ([email protected]) nanoparticles with controllable shell layer thicknesses are developed via in-situ aniline polymerization technology and characterized in detail. The results prove that the PANI shell layer with the adjustable and controllable thicknesses of 3–10 nm are completely stabilized on the surface of the BaTiO3 core. In addition, the [email protected] nanoparticles are regarded as the hybrid nanofillers to prepare PEN/[email protected] nanocomposite films with a PEN matrix. The research results indicate that the surface functionalized nanoparticles facilitate the compatibility and dispersibility of them in the PEN matrix, which improves the properties of the PEN/[email protected] nanocomposites. Specifically, the PEN/[email protected] nanocomposites exhibit thermal stability, excellent permittivity-frequency, and dielectric properties-temperature stability. Most importantly, the energy density of nanocomposites is maintained at over 70% at 180 °C compared with that at 25 °C. All these results reveal that a new way to prepare the high-performance PEN-based nanocomposites is established to fabricate an energy storage component in a high temperature environment. Full article
(This article belongs to the Special Issue Polymers for Electronic Applications)
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Open AccessArticle Polymeric Composites with Embedded Nanocrystalline Cellulose for the Removal of Iron(II) from Contaminated Water
Polymers 2018, 10(12), 1377; https://doi.org/10.3390/polym10121377
Received: 16 November 2018 / Revised: 8 December 2018 / Accepted: 9 December 2018 / Published: 12 December 2018
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Abstract
The exponential increase in heavy metal usage for industrial applications has led to the limited supply of clean water for human needs. Iron is one of the examples of heavy metals, which is responsible for an unpleasant taste of water and its discoloration,
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The exponential increase in heavy metal usage for industrial applications has led to the limited supply of clean water for human needs. Iron is one of the examples of heavy metals, which is responsible for an unpleasant taste of water and its discoloration, and is also associated with elevated health risks if it persists in drinking water for a prolonged period of time. The adsorption of a soluble form of iron (Fe2+) from water resources is generally accomplished in the presence of natural or synthetic polymers or nanoparticles, followed by their filtration from treated water. The self-assembly of these colloidal carriers into macroarchitectures can help in achieving the facile removal of metal-chelated materials from treated water and hence can reduce the cost and improve the efficiency of the water purification process. In this study, we aim to develop a facile one-pot strategy for the synthesis of polymeric composites with embedded nanocrystalline cellulose (NCC) for the chelation of iron(II) from contaminated water. The synthesis of the polymeric composites with embedded nanoparticles was achieved by the facile coating of ionic monomers on the surface of NCC, followed by their polymerization, crosslinking, and self-assembly in the form of three-dimensional architectures at room temperature. The composites prepared were analyzed for their physiochemical properties, antifouling properties, and for their iron(II)-chelation efficacies in vitro. The results indicate that the embedded-NCC polymeric composites have antifouling properties and exhibit superior iron(II)-chelation properties at both acidic and basic conditions. Full article
(This article belongs to the Special Issue Bio-Based Polymers for Engineered Green Materials)
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Open AccessReview Exploring Structure–Property Relationships of GAGs to Tailor ECM-Mimicking Hydrogels
Polymers 2018, 10(12), 1376; https://doi.org/10.3390/polym10121376
Received: 22 October 2018 / Revised: 3 December 2018 / Accepted: 9 December 2018 / Published: 11 December 2018
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Abstract
Glycosaminoglycans (GAGs) are a class of linear polysaccharides that are ubiquitous in the extracellular matrix (ECM) and on cell surfaces. Due to their key role in development, homeostasis, pathogenesis, and regeneration, GAGs are increasingly used in the design of ECM-mimicking hydrogels to stimulate
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Glycosaminoglycans (GAGs) are a class of linear polysaccharides that are ubiquitous in the extracellular matrix (ECM) and on cell surfaces. Due to their key role in development, homeostasis, pathogenesis, and regeneration, GAGs are increasingly used in the design of ECM-mimicking hydrogels to stimulate tissue formation and regenerative processes via specifically orchestrated cell-instructive signals. These applications first and foremost build on the ability of GAGs to effectively bind, protect, and release morphogens. The specificity and strength of morphogen-GAG interactions are largely governed by the number and spatial distribution of negatively charged sulfate groups carried by GAGs. Herein, we summarize a mean-field approach to quantify the density of ionizable groups, GAG concentration, and cross-linking degree of GAG-containing hydrogels on the basis of microslit electrokinetic experiments. We further present and discuss a continuum model of mucosa that accounts for charge regulation by glycan-ion pairing in biological contexts and under conditions of macromolecular crowding. Finally, we discuss the modulation of the morphogen binding and transport in GAG hydrogels by selective desulfation of the GAG component. Full article
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Open AccessArticle Study on Foaming Quality and Impact Property of Foamed Polypropylene Composites
Polymers 2018, 10(12), 1375; https://doi.org/10.3390/polym10121375
Received: 19 November 2018 / Revised: 6 December 2018 / Accepted: 7 December 2018 / Published: 11 December 2018
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Abstract
In the present work, foamed polypropylene (PP) composites were prepared by chemical foaming technology, and the foaming quality and impact property of the foamed PP composites were studied. The results showed that the foaming quality was significantly improved after the introduction of thermoplastic
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In the present work, foamed polypropylene (PP) composites were prepared by chemical foaming technology, and the foaming quality and impact property of the foamed PP composites were studied. The results showed that the foaming quality was significantly improved after the introduction of thermoplastic rubber (TPR) and polyolefin elastomer (POE). Meanwhile, it was found that the impact property depended on the intrinsic toughness and contribution of foams (cells) to the PP composites. Furthermore, the data regarding impact property in low temperature showed that when the temperature was between −80 and −20 °C, the impact properties of the foamed PP composites were higher than that of the unfoamed sample, which was due to the impact property being completely contributed by cells under this condition. Meanwhile, when the temperature ranged from −20 to 20 °C, the impact property of the unfoamed sample was higher, which was due to the PP matrix contributing more to the impact property under this temperature. This work significantly improved the foaming quality of foamed PP composites and provided reliable evidence for the improvement of impact property. Full article
(This article belongs to the Special Issue Polymeric Foams)
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Open AccessArticle UV-Curable Urethane Acrylate Resin from Palm Fatty Acid Distillate
Polymers 2018, 10(12), 1374; https://doi.org/10.3390/polym10121374
Received: 15 November 2018 / Revised: 5 December 2018 / Accepted: 6 December 2018 / Published: 11 December 2018
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Abstract
Palm fatty acid distillate (PFAD), is a by-product of the crude palm oil refining process. It comprises mainly of free fatty acids—around 45% palmitic and 33% oleic acids—as the major components. Ultra-violet (UV) curable urethane acrylate (UA) oligomers could be synthesized from PFAD,
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Palm fatty acid distillate (PFAD), is a by-product of the crude palm oil refining process. It comprises mainly of free fatty acids—around 45% palmitic and 33% oleic acids—as the major components. Ultra-violet (UV) curable urethane acrylate (UA) oligomers could be synthesized from PFAD, by the following procedure. A hydroxyl terminated macromer was first prepared by reacting PFAD with a mixture of isophthalic acid, phthalic anhydride, neopentagylcol (NPG), and pentaerythritol. The macromer was then reacted with 2-hydroxylethylacrylate (2HEA) and toluene diisocynate (TDI) to generate a resin, containing acrylate side chains for UV curable application. A series of UA resins were prepared by using 15, 25, 45, 55, and 70% of PFAD, respectively. The UA resin has Mw in the range of 3,200 to 27,000. They could be cured by UV irradiation at an intensity of 225 mW/cm2. Glass transition temperature (Tg) of the cured film was measured by differential scanning calorimeter (DSC), and hardness of the film was determined by a pendulum hardness tester, according to American Society for Testing and Materials (ASTM)4366. The resins were used in a wood-coating application. All of the cured films showed good adhesion, hardness, and chemical resistance except for the one using the 70% PFAD, which did not cure properly. Full article
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Open AccessArticle Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding
Polymers 2018, 10(12), 1373; https://doi.org/10.3390/polym10121373
Received: 22 November 2018 / Revised: 6 December 2018 / Accepted: 7 December 2018 / Published: 11 December 2018
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Abstract
In this study, the feasibility of co-grinding and the subsequent thermal rounding to produce spherical polymer blend particles for selective laser sintering (SLS) is demonstrated for polybutylene terephthalate (PBT) and polycarbonate (PC). The polymers are jointly comminuted in a planetary ball mill, and
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In this study, the feasibility of co-grinding and the subsequent thermal rounding to produce spherical polymer blend particles for selective laser sintering (SLS) is demonstrated for polybutylene terephthalate (PBT) and polycarbonate (PC). The polymers are jointly comminuted in a planetary ball mill, and the obtained product particles are rounded in a heated downer reactor. The size distribution of PBT–PC composite particles is characterized with laser diffraction particle sizing, while the shape and morphology are investigated via scanning electron microscopy (SEM). A thorough investigation and characterization of the polymer intermixing in single particles is achieved via staining techniques and Raman microscopy. Furthermore, polarized light microscopy on thin film cuts enables the visualization of polymer mixing inside the particles. Trans-esterification between PBT and PC during the process steps is investigated via vibrational spectroscopy and differential scanning calorimetry (DSC). In this way, a new process route for the production of novel polymer blend particle systems for SLS is developed and carefully analyzed. Full article
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Open AccessArticle Photocurable Bioinks for the 3D Pharming of Combination Therapies
Polymers 2018, 10(12), 1372; https://doi.org/10.3390/polym10121372
Received: 11 November 2018 / Revised: 7 December 2018 / Accepted: 10 December 2018 / Published: 11 December 2018
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Abstract
Combination therapies mediate drug synergy to improve treatment efficacy and convenience, leading to higher levels of compliance. However, there are challenges with their manufacturing as well as reduced flexibility in dosing options. This study reports on the design and characterization of a polypill
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Combination therapies mediate drug synergy to improve treatment efficacy and convenience, leading to higher levels of compliance. However, there are challenges with their manufacturing as well as reduced flexibility in dosing options. This study reports on the design and characterization of a polypill fabricated through the combination of material jetting and binder jetting for the treatment of hypertension. The drugs lisinopril and spironolactone were loaded into hydrophilic hyaluronic acid and hydrophobic poly(ethylene glycol) (PEG) photocurable bioinks, respectively, and dispensed through a piezoelectric nozzle onto a blank preform tablet composed of two attachable compartments fabricated via binder jetting 3D printing. The bioinks were photopolymerized and their mechanical properties were assessed via Instron testing. Scanning electron microscopy (SEM) was performed to indicate morphological analysis. The polypill was ensembled and drug release analysis was performed. Droplet formation of bioinks loaded with hydrophilic and hydrophobic active pharmaceutical ingredients (APIs) was achieved and subsequently polymerized after a controlled dosage was dispensed onto preform tablet compartments. High-performance liquid chromatography (HPLC) analysis showed sustained release profiles for each of the loaded compounds. This study confirms the potential of material jetting in conjunction with binder jetting techniques (powder-bed 3D printing), for the production of combination therapy oral dosage forms involving both hydrophilic and hydrophobic drugs. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymeric Materials)
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Open AccessArticle Incorporation of Carbon Nanofillers Tunes Mechanical and Electrical Percolation in PHBV:PLA Blends
Polymers 2018, 10(12), 1371; https://doi.org/10.3390/polym10121371
Received: 21 November 2018 / Revised: 7 December 2018 / Accepted: 8 December 2018 / Published: 11 December 2018
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Abstract
Biobased fillers, such as bio-derived cellulose, lignin byproducts, and biochar, can be used to modify the thermal, mechanical, and electrical properties of polymer composites. Biochar (BioC), in particular, is of interest for enhancing thermal and electrical conductivities in composites, and can potentially serve
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Biobased fillers, such as bio-derived cellulose, lignin byproducts, and biochar, can be used to modify the thermal, mechanical, and electrical properties of polymer composites. Biochar (BioC), in particular, is of interest for enhancing thermal and electrical conductivities in composites, and can potentially serve as a bio-derived graphitic carbon alternative for certain composite applications. In this work, we investigate a blended biopolymer system: poly(lactic acid) (PLA)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), and addition of carbon black (CB), a commonly used functional filler as a comparison for Kraft lignin-derived BioC. We present calculations and experimental results for phase-separation and nanofiller phase affinity in this system, indicating that the CB localizes in the PHBV phase of the immiscible PHBV:PLA blends. The addition of BioC led to a deleterious reaction with the biopolymers, as indicated by blend morphology, differential scanning calorimetry showing significant melting peak reduction for the PLA phase, and a reduction in melt viscosity. For the CB nanofilled composites, electrical conductivity and dynamic mechanical analysis supported the ability to use phase separation in these blends to tune the percolation of mechanical and electrical properties, with a minimum percolation threshold found for the 80:20 blends of 1.6 wt.% CB. At 2% BioC (approximately the percolation threshold for CB), the 80:20 BioC nanocomposites had a resistance of 3.43 × 10 8 Ω as compared to 2.99 × 10 8 Ω for the CB, indicating that BioC could potentially perform comparably to CB as a conductive nanofiller if the processing challenges can be overcome for higher BioC loadings. Full article
(This article belongs to the Special Issue Recent Advances in Bioplastics)
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Open AccessArticle Polymeric Nanocomposites Membranes with High Permittivity Based on PVA-ZnO Nanoparticles for Potential Applications in Flexible Electronics
Polymers 2018, 10(12), 1370; https://doi.org/10.3390/polym10121370
Received: 24 October 2018 / Revised: 4 December 2018 / Accepted: 7 December 2018 / Published: 11 December 2018
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Abstract
This study reports the optical, structural, electrical and dielectric properties of Poly (vinyl alcohol) thin films membranes with embedded ZnO nanoparticles (PVA/ZnO) obtained by the solution casting method at low temperature of deposition. Fourier Transform Infrared spectra showed the characteristics peaks, which correspond
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This study reports the optical, structural, electrical and dielectric properties of Poly (vinyl alcohol) thin films membranes with embedded ZnO nanoparticles (PVA/ZnO) obtained by the solution casting method at low temperature of deposition. Fourier Transform Infrared spectra showed the characteristics peaks, which correspond to O–H and Zn–O bonds present in the hybrid material. The X-ray diffraction patterns indicated the presence of ZnO structure into the films. The composite material showed low absorbance and a wide band of gap energy from 5.5 to 5.83 eV. The surface morphology for the thin films of PVA/ZnO was studied by Atomic Force Microscopy and Scanning Electron Microscopy. The electrical properties of the membranes were also characterized by current-voltage characteristics and the DC conductivity showed Arrhenius behavior with values of activation energy from 0.62 to 0.78 eV and maximum conductivity at 2.4 × 10−12 S/cm. The dielectric properties of the nanocomposites were measured from low to high frequencies, and the results showed a high dielectric constant (ε) in the order of 104 at low frequency and values from ε ≈ 2000 to 100 in the range of 1 KHz–1 MHz respectively. The properties of PVA/ZnO such as the high permittivity and the low temperature of processing make it a suitable material for potential applications in the development of flexible electronic devices. Full article
(This article belongs to the Special Issue Polymers for Electronic Applications)
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Open AccessArticle Sometimes the Same, Sometimes Different: Understanding Self-Assembly Algorithms in Coordination Networks
Polymers 2018, 10(12), 1369; https://doi.org/10.3390/polym10121369
Received: 23 November 2018 / Revised: 7 December 2018 / Accepted: 8 December 2018 / Published: 11 December 2018
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Abstract
The syntheses and characterizations of three new ligands containing two 4,2′:6′,4″-tpy or two 3,2′:6′,3″-tpy metal-binding domains are reported. The ligands possess different alkyloxy functionalities attached to the central phenylene spacer: n-pentyloxy in 3, 4-phenyl-n-butoxy in 4, benzyloxy in
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The syntheses and characterizations of three new ligands containing two 4,2′:6′,4″-tpy or two 3,2′:6′,3″-tpy metal-binding domains are reported. The ligands possess different alkyloxy functionalities attached to the central phenylene spacer: n-pentyloxy in 3, 4-phenyl-n-butoxy in 4, benzyloxy in 5. Crystal growth under ambient conditions has led to the formation of {[Co(NCS)2(3)]·0.8C6H4Cl2}n and {[Co(NCS)2(4)]·1.6H2O·1.2C6H4Cl2}n, with structures confirmed by single crystal X-ray diffraction. Both the cobalt(II) center and ligand 3 or 4 act as 4-connecting nodes and both {[Co(NCS)2(3)]·0.8C6H4Cl2}n and {[Co(NCS)2(4)]·1.6H2O·1.2C6H4Cl2}n possess a 3D cds net despite the fact that 3 and 4 contain two 4,2′:6′,4″-tpy and two 3,2′:6′,3″-tpy units, respectively. Taken in conjunction with previously reported data, the results indicate that the role of the alkyloxy substituent is more significant than the choice of 4,2′:6′,4″- or 3,2′:6′,3″-tpy isomer in determining the assembly of a particular 3D net. The combination of Co(NCS)2 with 5 resulted in the formation of the discrete molecular complex [Co(NCS)2(MeOH)2(5)2]·2CHCl3·2MeOH in which 5 acts as a monodentate ligand. The pendant phenyls and both coordinated and non-coordinated 4,2′:6′,4″-tpy units are involved in efficient π-stacking interactions. Full article
(This article belongs to the Special Issue Advances in Coordination Polymers)
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Open AccessArticle Multiscale Simulation of Branched Nanofillers on Young’s Modulus of Polymer Nanocomposites
Polymers 2018, 10(12), 1368; https://doi.org/10.3390/polym10121368
Received: 13 November 2018 / Revised: 5 December 2018 / Accepted: 7 December 2018 / Published: 10 December 2018
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Abstract
Nanoscale tailoring the filler morphology in experiment offers new opportunities to modulate the mechanical properties of polymer nanocomposites. Based on the conventical rod and experimentally available tetrapod filler, I compare the nanofiller dispersion and elastic moduli of these two kinds of nanocomposites via
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Nanoscale tailoring the filler morphology in experiment offers new opportunities to modulate the mechanical properties of polymer nanocomposites. Based on the conventical rod and experimentally available tetrapod filler, I compare the nanofiller dispersion and elastic moduli of these two kinds of nanocomposites via molecular dynamics simulation and a lattice spring model. The results show that the tetrapod has better dispersion than the rod, which is facilitate forming the percolation network and thus benefitting the mechanical reinforcement. The elastic modulus of tetrapod filled nanocomposites is much higher than those filled with rod, and the modulus disparity strongly depends on the aspect ratio of fillers and particle-polymer interaction, which agrees well with experimental results. From the stress distribution analysis on single particles, it is concluded that the mechanical disparity between bare rod and tetrapod filled composites is due to the effective stress transfer in the polymer/tetrapod composites. Full article
(This article belongs to the Special Issue Multiscale Modeling of Polymers)
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Open AccessArticle Facile Fabrication and Characterization of Improved Proton Conducting Sulfonated Poly(Arylene Biphenylether Sulfone) Blocks Containing Fluorinated Hydrophobic Units for Proton Exchange Membrane Fuel Cell Applications
Polymers 2018, 10(12), 1367; https://doi.org/10.3390/polym10121367
Received: 28 November 2018 / Revised: 7 December 2018 / Accepted: 8 December 2018 / Published: 10 December 2018
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Abstract
Sulfonated poly(arylene biphenylether sulfone)-poly(arylene ether) (SPABES-PAE) block copolymers by controlling the molar ratio of SPABES and PAE oligomers were successfully synthesized, and the performances of SPABES-PAE (1:2, 1:1, and 2:1) membranes were compared with Nafion 212. The prepared membranes including fluorinated hydrophobic units
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Sulfonated poly(arylene biphenylether sulfone)-poly(arylene ether) (SPABES-PAE) block copolymers by controlling the molar ratio of SPABES and PAE oligomers were successfully synthesized, and the performances of SPABES-PAE (1:2, 1:1, and 2:1) membranes were compared with Nafion 212. The prepared membranes including fluorinated hydrophobic units were stable against heat, nucleophile attack, and physio-chemical durability during the tests. Moreover, the polymers exhibited better solubility in a variety of solvents. The chemical structure of SPABES-PAEs was investigated by 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). The membrane of SPABES-PAEs was fabricated by the solution casting method, and the membranes were very flexible and transparent with a thickness of 70–90 μm. The morphology of the membranes was observed using atomic force microscope and the ionic domain size was proved by small angle X-ray scattering (SAXS) measurement. The incorporation of polymers including fluorinated units allowed the membranes to provide unprecedented oxidative and dimensional stabilities, as verified from the results of ex situ durability tests and water uptake capacity, respectively. By the collective efforts, we observed an enhanced water retention capacity, reasonable dimensional stability and high proton conductivity, and the peak power density of the SPABES-PAE (2:1) was 333.29 mW·cm−2 at 60 °C under 100% relative humidity (RH). Full article
(This article belongs to the Special Issue Polymeric Materials for Electrochemical Energy Conversion and Storage)
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