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Polymers, Volume 9, Issue 7 (July 2017)

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Cover Story (view full-size image) ABC star terpolymers are made of immiscible blocks and form vesicles with nanodomains that allow [...] Read more.
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Open AccessArticle Two-Photon-Induced Microstereolithography of Chitosan-g-Oligolactides as a Function of Their Stereochemical Composition
Polymers 2017, 9(7), 302; https://doi.org/10.3390/polym9070302
Received: 12 June 2017 / Revised: 20 July 2017 / Accepted: 21 July 2017 / Published: 24 July 2017
Cited by 2 | PDF Full-text (4898 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for
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Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for the synthesis on the grafting yield and copolymer’s behavior were evaluated using fractional analysis, FTIR-spectroscopy, dynamic light scattering, and UV-spectrophotometry. The lowest copolymer yield was found for the system based on chitosan with higher molecular weight, while the samples consisting of low-molecular weight chitosan showed higher grafting degrees, which were comparable in both the cases of l,l- or l,d-oligolactide grafting. The copolymer processability in the course of two-photon stereolithography was evaluated as a function of the copolymer’s characteristics and stereolithography conditions. The structure and mechanical properties of the model film samples and fabricated 3D hydrogels were studied using optical and scanning electron microscopy, as well as by using tensile and nanoindenter devices. The application of copolymer with oligo(l,d-lactide) side chains led to higher processability during two-photon stereolithography in terms of the response to the laser beam, reproduction of the digital model, and the mechanical properties of the fabricated hydrogels. Full article
(This article belongs to the Special Issue Three-Dimensional Structures: Fabrication and Application)
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Open AccessArticle Synthesis and Phase Transition of Poly(N-isopropylacrylamide)-Based Thermo-Sensitive Cyclic Brush Polymer
Polymers 2017, 9(7), 301; https://doi.org/10.3390/polym9070301
Received: 24 June 2017 / Revised: 19 July 2017 / Accepted: 21 July 2017 / Published: 23 July 2017
Cited by 6 | PDF Full-text (2346 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Polymers with advanced topological architectures are promising materials for wide applications due to their structure-generated unique properties different from that of the linear analogues. The elegant integration of stimuli-responsive polymers with such advanced architectures can create novel materials with virtues from both moieties,
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Polymers with advanced topological architectures are promising materials for wide applications due to their structure-generated unique properties different from that of the linear analogues. The elegant integration of stimuli-responsive polymers with such advanced architectures can create novel materials with virtues from both moieties, are thus a hot subject of research for both fundamental and practical investigations. To fabricate cyclic brush polymer-based intelligent materials for biomedical applications, herein, we designed and synthesized thermo-sensitive cyclic brush polymers with poly(N-isopropylacrylamide) (PNIPAAm) brushes by controlled living radical polymerization using cyclic multimacroinitiator. The thermo-induced phase transition behaviors of the resultant cyclic brush polymers with different compositions were investigated in detail by temperature-dependent optical transmittance measurements, and compared with the properties of bottlebrush and linear counterparts. Interestingly, the cloud point transition temperature (Tcp) of cyclic brush PNIPAAm could be regulated by the chain length of PNIPAAm brush. Although the bottlebrush polymers with the same composition exhibited similarly structurally dependent Tcps behaviors to the cyclic brush polymers, the cyclic brush PNIPAAm did show higher critical aggregation concentration (CAC) and enhanced stability against dilution than the bottlebrush counterpart. The readily tailorable Tcps together with the ability to form highly stable nanoparticles makes thermo-sensitive cyclic brush PNIPAAm a promising candidate for controlled drug delivery. Full article
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Open AccessArticle Enhancement of Wound Healing in Normal and Diabetic Mice by Topical Application of Amorphous Polyphosphate. Superior Effect of a Host–Guest Composite Material Composed of Collagen (Host) and Polyphosphate (Guest)
Polymers 2017, 9(7), 300; https://doi.org/10.3390/polym9070300
Received: 2 July 2017 / Revised: 16 July 2017 / Accepted: 20 July 2017 / Published: 22 July 2017
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Abstract
The effect of polyphosphate (polyP) microparticles on wound healing was tested both in vitro and in a mice model in vivo. Two approaches were used: pure salts of polyphosphate, fabricated as amorphous microparticles (MPs, consisting of calcium and magnesium salts of polyP, “Ca–polyp-MPs”
[...] Read more.
The effect of polyphosphate (polyP) microparticles on wound healing was tested both in vitro and in a mice model in vivo. Two approaches were used: pure salts of polyphosphate, fabricated as amorphous microparticles (MPs, consisting of calcium and magnesium salts of polyP, “Ca–polyp-MPs” and “Mg–polyp-MPs”), and host–guest composite particles, prepared from amorphous collagen (host) and polyphosphate (guest), termed “col/polyp-MPs”. Animal experiments with polyP on healing of excisional wounds were performed using both normal mice and diabetic mice. After a healing period of 7 days “Ca–polyp-MP” significantly improved re-epithelialization in normal mice from 31% (control) to 72% (polyP microparticle-treated). Importantly, in diabetic mice, particularly the host–guest particles “col/polyp-MP”, increased the rate of re-epithelialization to ≈40% (control, 23%). In addition, those particles increased the expression of COL-I and COL-III as well as the expression the α-smooth muscle actin and the plasminogen activator inhibitor-1. We propose that “Ca–polyp-MPs”, and particularly the host–guest “col/polyp-MPs” are useful for topical treatment of wounds. Full article
(This article belongs to the Special Issue Host-Guest Polymer Complexes)
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Open AccessArticle Upconversion Nanophosphor-Involved Molecularly Imprinted Fluorescent Polymers for Sensitive and Specific Recognition of Sterigmatocystin
Polymers 2017, 9(7), 299; https://doi.org/10.3390/polym9070299
Received: 11 June 2017 / Revised: 19 July 2017 / Accepted: 19 July 2017 / Published: 22 July 2017
Cited by 3 | PDF Full-text (2414 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Originated from the bottom-up synthetic strategy, molecularly imprinted polymers (MIPs) possess the inherent ability of selective and specific recognition and binding of the target analytes, with their structural cavities that can match the target molecules in respect to size, shape, and functional groups.
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Originated from the bottom-up synthetic strategy, molecularly imprinted polymers (MIPs) possess the inherent ability of selective and specific recognition and binding of the target analytes, with their structural cavities that can match the target molecules in respect to size, shape, and functional groups. Herein, based on the high selectivity of MIPs and the fluorescence properties of the β-NaYF4:Yb3+, Er3+ upconversion nanoparticles, MIPs with both specificity and fluorescent signals are fabricated to recognize trace sterigmatocystin (ST) with high selectivity and sensitivity. The structure analogue of ST, 1,8-dihydroxyanthraquinone (DT), was employed as the template molecule, acrylamide as the functional monomer, 3-methacryloyloxypropyltrimethoxysilane as the crosslinking agent, and a new molecular imprinting technique of non-aqueous sol-gel method is used to synthesize a molecularly imprinted material with high selectivity to ST. Under optimal conditions, the fluorescence enhancement of fluorescent MIPs increased as the concentration of ST increased. In the range of 0.05–1.0 mg L−1, fluorescence enhancement and the concentration showed a good linear relationship with a detection limit of 0.013 mg L−1. Real sample analysis achieved the recoveries of 83.8–88.8% (RSD 5.1%) for rice, 82.1–87.5% (RSD 4.6%) for maize, and 80.6–89.2% (RSD 3.0%) for soybeans, respectively, revealing the feasibility of the developed method. Full article
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Open AccessArticle Additives Type Schiff’s Base as Modifiers of the Optical Response in Holographic Polymer-Dispersed Liquid Crystals
Polymers 2017, 9(7), 298; https://doi.org/10.3390/polym9070298
Received: 9 June 2017 / Revised: 6 July 2017 / Accepted: 19 July 2017 / Published: 21 July 2017
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Abstract
Schiff’s bases with specific π-electron system have been synthesized and used as additives in holographic polymer-dispersed liquid crystals. It was observed that these substances modify different parameters such as current intensity, voltage, and diffracted light intensity. In addition, the maximum diffraction efficiency obtained
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Schiff’s bases with specific π-electron system have been synthesized and used as additives in holographic polymer-dispersed liquid crystals. It was observed that these substances modify different parameters such as current intensity, voltage, and diffracted light intensity. In addition, the maximum diffraction efficiency obtained in the reconstruction of the holograms is related to the additive molecule. We propose a relationship between this behavior and the molecular structure of these substances. Full article
(This article belongs to the Special Issue Photo-Responsive Polymers)
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Open AccessArticle Biphasic Calcium Phosphate (BCP)-Immobilized Porous Poly (d,l-Lactic-co-Glycolic Acid) Microspheres Enhance Osteogenic Activities of Osteoblasts
Polymers 2017, 9(7), 297; https://doi.org/10.3390/polym9070297
Received: 27 June 2017 / Revised: 11 July 2017 / Accepted: 18 July 2017 / Published: 21 July 2017
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Abstract
The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces
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The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces were modified with l-lysine (aminated-PMSs), whereas the BCP NPs were modified with heparin–dopamine (Hep-DOPA) to obtain heparinized–BCP (Hep-BCP) NPs. BCP-IM-PMSs were fabricated via electrostatic interactions between the Hep-BCP NPs and aminated-PMSs. The fabricated BCP-IM-PMSs showed an interconnected pore structure. In vitro studies showed that MG-63 cells cultured on BCP-IM-PMSs had increased alkaline phosphatase activity, calcium content, and mRNA expression of osteocalcin (OCN) and osteopontin (OPN) compared with cells cultured on PMSs. These data suggest that BCP NP-immobilized PMSs have the potential to enhance osteogenic activity. Full article
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Open AccessArticle Design and Study of a Novel Thermal-Resistant and Shear-Stable Amphoteric Polyacrylamide in High-Salinity Solution
Polymers 2017, 9(7), 296; https://doi.org/10.3390/polym9070296
Received: 2 June 2017 / Revised: 5 July 2017 / Accepted: 17 July 2017 / Published: 21 July 2017
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Abstract
Abstract: Water-soluble polymers are widely used in oilfields. The rheological behaviors of these polymers in high-salinity solution are very important for stimulation of high-salinity reservoirs. In this work, a novel thermal-resistant and shear-stable amphoteric polyacrylamide (PASD), prepared from acrylamide (AM), sodium styrene
[...] Read more.
Abstract: Water-soluble polymers are widely used in oilfields. The rheological behaviors of these polymers in high-salinity solution are very important for stimulation of high-salinity reservoirs. In this work, a novel thermal-resistant and shear-stable amphoteric polyacrylamide (PASD), prepared from acrylamide (AM), sodium styrene sulfonate (SSS), and acryloxyethyl trimethylammonium chloride (DAC) monomers, was prepared by free-radical polymerization in high-salinity solution. The amphoteric polyacrylamide was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy (1H NMR), elemental analysis, thermogravimetric analysis (TG), and scanning electron microscopy (SEM). The amphoteric polyacrylamide exhibited excellent salinity tolerance. The slow increase in apparent viscosity of the polymer with increase in salinity was interesting. The amphoteric polyacrylamide showed perfect temperature resistance in high-salinity solution. The viscosity retention reached 38.9% at 120 °C and was restored to 87.8% of its initial viscosity when temperature was decreased to room temperature. The retention ratio of apparent viscosity reached 49.7% at 170 s−1 and could still retain it at 25.8% at 1000 s−1. All these results demonstrated that PASD had excellent thermal-resistance and shear-stability in high-salinity solution. We expect that this work could provide a new strategy to design polymers with excellent salinity-tolerance, thermal-resistance, and shear-stability performances. Full article
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Open AccessArticle Light-Driven Rotation and Pitch Tuning of Self-Organized Cholesteric Gratings Formed in a Semi-Free Film
Polymers 2017, 9(7), 295; https://doi.org/10.3390/polym9070295
Received: 29 June 2017 / Revised: 18 July 2017 / Accepted: 19 July 2017 / Published: 21 July 2017
Cited by 5 | PDF Full-text (4493 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cholesteric liquid crystal (CLC) has attracted intensive attention due to its ability to form a periodic helical structure with broad tunability. CLC gratings in open systems are especially promising in sensing and micromanipulation. However, there is still much to learn about the inherent
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Cholesteric liquid crystal (CLC) has attracted intensive attention due to its ability to form a periodic helical structure with broad tunability. CLC gratings in open systems are especially promising in sensing and micromanipulation. However, there is still much to learn about the inherent mechanism of such gratings. We investigate the light-driven rotation and pitch-tuning behaviors of CLC gratings in semi-free films which are formed by spin-coating the CLC mixtures onto planarly photoaligned substrates. The doped azobenzene chiral molecular switch supplies great flexibility to realize the continuous grating rotation. The maximum continuous rotational angle reaches 987.8°. Moreover, dependencies of light-driven rotation and pitch tuning on the dopant concentration and exposure are studied. The model of director configuration in the semi-free film is constructed. Precise beam steering and synchronous micromanipulation are also demonstrated. Our work may provide new opportunities for the CLC grating in applications of beam steering, micromanipulation, and sensing. Full article
(This article belongs to the Special Issue Photo-Responsive Polymers)
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Open AccessArticle Gas Barrier, Thermal, Mechanical and Rheological Properties of Highly Aligned Graphene-LDPE Nanocomposites
Polymers 2017, 9(7), 294; https://doi.org/10.3390/polym9070294
Received: 14 June 2017 / Revised: 17 July 2017 / Accepted: 18 July 2017 / Published: 21 July 2017
Cited by 8 | PDF Full-text (2362 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This contribution reports on properties of low-density polyethylene-based composites filled with different amounts of graphene nanoplatelets. The studied samples were prepared in the form of films by means of the precoating technique and single screw melt-extrusion, which yields a highly ordered arrangement of
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This contribution reports on properties of low-density polyethylene-based composites filled with different amounts of graphene nanoplatelets. The studied samples were prepared in the form of films by means of the precoating technique and single screw melt-extrusion, which yields a highly ordered arrangement of graphene flakes and results in a strong anisotropy of composites morphology. The performed tests of gas permeability reveal a drastic decrease of this property with increasing filler content. A clear correlation is found between permeability and free volume fraction in the material, the latter evaluated by means of positron annihilation spectroscopy. A strong anisotropy of the thermal conductivity is also achieved and the thermal conductivity along the extrusion direction for samples filled with 7.5 wt % of GnP (graphene nanoplatelets) reached 2.2 W/m·K. At the same time, when measured through a plane, a slight decrease of thermal conductivity is found. The use of GnP filler leads also to improvements of mechanical properties. The increase of Young’s modulus and tensile strength are reached as the composites become more brittle. Full article
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Open AccessArticle Self-Assembly of Double Hydrophilic Poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) Block Copolymers in Aqueous Solution
Polymers 2017, 9(7), 293; https://doi.org/10.3390/polym9070293
Received: 23 June 2017 / Revised: 14 July 2017 / Accepted: 16 July 2017 / Published: 20 July 2017
Cited by 7 | PDF Full-text (2974 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP
[...] Read more.
The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP is varied in order to study the effect of block ratio on the self-assembly process. Studies via dynamic light scattering, static light scattering as well as microscopy techniques, e.g., cryo scanning electron microscopy or laser scanning confocal microscopy, show the formation of spherical particles in an aqueous solution with sizes between 300 and 400 nm. Particles of the DHBCs are formed without the influence of external stimuli. Moreover, the efficiency of self-assembly formation relies significantly on the molar ratio of the utilized blocks. The nature of the formed structures relies further on the concentration, and indications of particular and vesicular structures are found. Full article
(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)
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Open AccessArticle Preparation of Fluoroalkyl End-Capped Vinyltrimethoxysilane Oligomeric Silica Nanocomposites Containing Gluconamide Units Possessing Highly Oleophobic/Superhydrophobic, Highly Oleophobic/Superhydrophilic, and Superoleophilic/Superhydrophobic Characteristics on the Modified Surfaces
Polymers 2017, 9(7), 292; https://doi.org/10.3390/polym9070292
Received: 2 June 2017 / Revised: 12 July 2017 / Accepted: 18 July 2017 / Published: 20 July 2017
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Abstract
Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2-CHSi(OMe)3)n-RF (RF-(VM)n-RF)] undergoes the sol-gel reaction in the presence of N-(3-triethoxysilylpropyl)gluconamide [Glu-Si(OEt)3] under alkaline conditions to afford the corresponding fluorinated oligomeric
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Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2-CHSi(OMe)3)n-RF (RF-(VM)n-RF)] undergoes the sol-gel reaction in the presence of N-(3-triethoxysilylpropyl)gluconamide [Glu-Si(OEt)3] under alkaline conditions to afford the corresponding fluorinated oligomeric silica nanocomposites containing gluconamide units [RF-(VM-SiO3/2)n-RF/Glu-SiO3/2]. These obtained nanocomposites were applied to the surface modification of glass to provide the unique wettability characteristics such as highly oleophobic/superhydrophobic and highly oleophobic/superhydrophilic on the modified surfaces under a variety of conditions. Such a highly oleophobic/superhydrophobic characteristic was also observed on the modified PET (polyethylene terephthalate) fabric swatch, which was prepared under similar conditions, and this modified PET fabric swatch was applied to the separation membrane for the separation of the mixture of fluorocarbon oil and hydrocarbon oil. The RF-(VM-SiO3/2)n-RF/Glu-SiO3/2 nanocomposites, which were prepared under lower feed amounts of basic catalyst (ammonia), were found to cause gelation in water. Interestingly, it was demonstrated that these gelling nanocomposites are also applied to the surface modification of the PET fabric swatch to give a highly oleophobic/superhydrophobic characteristic on the surface. On the other hand, the modified glass surfaces treated with the corresponding nanocomposite possessing no gelling ability were found to supply the usual hydrophobic characteristic with a highly oleophobic property. More interestingly, the wettability change on the modified PET fabric swatch from highly oleophobic to superoleophilic was observed, and remained superhydrophobic after immersing the modified PET fabric swatch into water. Full article
(This article belongs to the Special Issue Fluorinated Polymers)
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Open AccessArticle Electronically Stabilized Copoly(Styrene-Acrylic Acid) Submicrocapsules Prepared by Miniemulsion Copolymerization
Polymers 2017, 9(7), 291; https://doi.org/10.3390/polym9070291
Received: 1 July 2017 / Revised: 17 July 2017 / Accepted: 20 July 2017 / Published: 20 July 2017
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Abstract
This work reports the preparation and characterization of poly(styrene-acrylic acid) (St/AA) submicrocapsules by using the miniemulsion copolymerization method. AA was introduced to miniemulsion polymerization of St to increase the zeta potential and the resulting electrostatic stability of St/AA submicrocapsules. Phytoncide oil was adopted
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This work reports the preparation and characterization of poly(styrene-acrylic acid) (St/AA) submicrocapsules by using the miniemulsion copolymerization method. AA was introduced to miniemulsion polymerization of St to increase the zeta potential and the resulting electrostatic stability of St/AA submicrocapsules. Phytoncide oil was adopted as the core model material. Miniemulsion copolymerization of St and AA was conducted at a fixed monomer concentration (0.172 mol) with a varying monomer feed ratio [AA]/[St] (0.2, 0.25, 0.33, 0.5, and 1.0). Concentrations of initiator (azobisisobutyronitrile; 1.0 × 10−3, 2.0 × 10−3, 3.0 × 10−3, and 4.0 × 10−3 mol/mol of monomer) and surfactant (sodium dodecyl sulfate; 0.6 × 10−3, 1.0 × 10−3, and 1.4 × 10−3 mol) were also controlled to optimize the miniemulsion copolymerization of St and AA. Dynamic light scattering and microscopic analyses confirmed the optimum condition of miniemulsion copolymerization of St and AA. Long-term colloidal stability of aqueous St/AA submicrocapsule suspension was evaluated by using TurbiscanTM Lab. In this work, the optimum condition for miniemulsion copolymerization of St and AA was determined ([AA]/[St] = 0.33; [SDS] = 1.0 × 10−3 mol; [AIBN] = 2.0 × 10−3 mol/mol of monomer). St/AA submicrocapsules prepared at the optimum condition (392.6 nm and −55.2 mV of mean particle size and zeta potential, respectively) showed almost no variations in backscattering intensity (stable colloids without aggregation). Full article
(This article belongs to the Special Issue Emulsion Polymerization)
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Open AccessArticle Polymerizable Ionic Liquid Crystals Comprising Polyoxometalate Clusters toward Inorganic-Organic Hybrid Solid Electrolytes
Polymers 2017, 9(7), 290; https://doi.org/10.3390/polym9070290
Received: 15 June 2017 / Revised: 14 July 2017 / Accepted: 17 July 2017 / Published: 20 July 2017
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Abstract
Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is
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Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is employing a thermally-stable inorganic component and a structurally-flexible organic moiety to construct inorganic-organic hybrid materials. Ionic liquids as the organic component will be advantageous for the emergence of high conductivity, and polyoxometalate, such as heteropolyacids, are well-known as inorganic proton conductors. Here, newly-designed ionic liquid imidazolium cations, having a polymerizable methacryl group (denoted as MAImC1), were successfully hybridized with heteropolyanions of [PW12O40]3− (PW12) to form inorganic-organic hybrid monomers of MAImC1-PW12. The synthetic procedure of MAImC1-PW12 was a simple ion-exchange reaction, being generally applicable to several polyoxometalates, in principle. MAImC1-PW12 was obtained as single crystals, and its molecular and crystal structures were clearly revealed. Additionally, the hybrid monomer of MAImC1-PW12 was polymerized by a radical polymerization using AIBN as an initiator. Some of the resulting inorganic-organic hybrid polymers exhibited conductivity of 10−4 S·cm−1 order under humidified conditions at 313 K. Full article
(This article belongs to the Special Issue Conductive Polymers 2017)
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Open AccessArticle Effect of Plasticizer Type on Tensile Property and In Vitro Indomethacin Release of Thin Films Based on Low-Methoxyl Pectin
Polymers 2017, 9(7), 289; https://doi.org/10.3390/polym9070289
Received: 7 June 2017 / Revised: 10 July 2017 / Accepted: 19 July 2017 / Published: 20 July 2017
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Abstract
This study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w)
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This study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w) on mechanical and thermal properties of LMP films as well as on in vitro release of indomethacin were evaluated. Without any plasticizer, a brittle LMP film with low tensile strength and % elongation at break was obtained. Addition of plasticizers from 20% to 40% caused reduction in the tensile strength and Young’s modulus values, whereas percent elongation was increased. Forty percent Gly-plasticized and PG-plasticized films were selected to deliver indomethacin in comparison with non-plasticized film. No significant difference in indomethacin release profiles was displayed between the films. The analysis of indomethacin release model indicated that more than one drug release mechanism from the film formulation was involved and possibly the combination of both diffusion and erosion. Even though indomethacin incorporated in non-plasticized film showed similar release profile, Gly or PG should be added to enhanced film flexibility and decrease film brittleness. Full article
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Open AccessArticle Ultra High Electrical Performance of Nano Nickel Oxide and Polyaniline Composite Materials
Polymers 2017, 9(7), 288; https://doi.org/10.3390/polym9070288
Received: 7 June 2017 / Revised: 10 July 2017 / Accepted: 18 July 2017 / Published: 20 July 2017
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Abstract
The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD) as the template agent.
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The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD) as the template agent. The experimental results revealed that the composite electrode processed a high specific capacitance (2122.75 F·g−1 at 0.1 A·g−1 in 0.05 M KI electrolyte solution), superior energy density (64.05 Wh·kg−1 at 0.2 A·g−1 in the two-electrode system) and excellent cycle performance (86% capacitance retention after 1000 cycles at 1.5 A·g−1). All those ultra-high electrical performances owe to the KI active material in the electrolyte and the PANI coated nano-NiO structure. Full article
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