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AbstractWith 2-acrylamido-2-methylpropanesulfonic acid (AMPS), YX-1 (a monomer containing an amide group) as the main chain, DX-2 (a monomer containing a hydrophobic group), N-vinylpyrrolidone (NVP) as the side chain, the high temperature resistant suspension stabilizer for spacer was prepared by free radical aqueous solution polymerization and characterized. The structure was characterized by fourier transform infrared (FTIR) spectroscopy and thermogravimetry-differential thermal analysis (TG-DTA), which proved that the synthesized product was the target product. The performance of the copolymer was evaluated. The experimental results showed that it could be used in the spacer fluid at 30 ∼ 210 °C, and its sedimentation performance could also meet the requirements in the spacer fluid system containing saturated brine. In order to explore the mechanism of the polymer, the polymer solution was tested by six-speed rotational viscometer, pyrene fluorescence probe test, environmental scanning electron microscopy (ESEM) test, and the isolation solution containing the copolymer was tested by Zeta potential test and X-ray diffraction (XRD). Based on the above test results, it is shown that the suspension stabilizer synthesized in this paper has the characteristics of thickening, physical plugging, chemical and physical adsorption, which can effectively ensure that the spacer fluid has excellent suspension performance at high temperature. [ABSTRACT FROM AUTHOR]

Tuff has been used as a natural building stone in the construction industry since the earliest times. Tuff is slight, simple to manufacture, and has good isolation qualities, which is why it is used so frequently despite its low strength characteristics and high porosity. In this study, samples of white and pink tuff from the regions of Derbent and Gümele districts of Eskisehir province were treated with a water-based (water-soluble) copolymer bath to evaluate their endurance to atmospheric conditions. Spherical samples were subjected to 30-minute slake durability index testing in a water-based copolymer bath. The index values of the initial spherical samples were contrasted with the index values from the fourth cycle of the spherical samples that had received the copolymer bath treatment. Although the index values of the original spherical samples were determined to be 92.22% and 95.32%, respectively, the index values of the spherical sample sets treated with a water-based copolymer bath were determined to be 98.29% and 98.83%, respectively. The study results indicate that spherical samples with a water-based copolymer bath treatment had a greater impact on improving the slake durability index values compared to spherical samples without treatment. [ABSTRACT FROM AUTHOR]

This article reports on the synthesis of materials containing both a fluoroalkyl group and a diazonaphthoquinone (DNQ) moiety as well as the fabrication of negative- and positive-tone stencil patterns. Additionally, the photoreaction mechanism that contributes to the pattern formation process is discussed, and the application of these materials is explored in the pixel-formation process in organic light-emitting diode (OLED) displays. Fluoroalkylated diazonaphthoquinone (RF2D1) was synthesized using chemically binding a DNQ unit, which can be converted into carboxylic acid derivatives having stronger polarity, with two fluorinated alkyl chains. The purified compound is found to be soluble in a nonpolar fluorous solvent and can be uniformly coated as a thin film. When the thin film of RF2D1 is exposed to 365 nm UV light, its solubility in a fluorous solvent decreases due to the Wolff rearrangement and subsequent hydrolysis of a ketene moiety. In contrast, when a mixture of RF2D1 and a hydrophobic, fluorinated copolymer is tested for the patterning process, the copolymer delays the conversion of the ketene intermediate to carboxylic acid, resulting in the dissolution of the exposed areas in the fluorous solvent. Finally, the applicability of these materials in micropatterning is demonstrated by adopting them in the orthogonal photolithography process to create pixels of OLEDs. [ABSTRACT FROM AUTHOR]

Heterogeneous membranes made of a polymer matrix and containing nano-metric fillers in their structure may present improved physicochemical and process properties compared to homogeneous membranes made only of polymer materials. Membranes made of a PEBAX®2533 block copolymer were tested with fillers such as ZIF-8, SiO2 and POSS-Ph being dosed to them. The material analysis and process tests indicate that these nanomaterials can be used as fillers for heterogeneous membranes. Chemometric analyses determined the influence of individual fillers on selected physicochemical properties of the materials which were used to produce the membranes. For specific concentrations of these fillers, improvement in the permeability and selectivity of the membranes, or at least in one of these parameters, was achieved. The greatest increase in permeability against the homogeneous membrane was obtained for membranes containing 10 wt% ZIF-8 (for CO2, an increase of 2.07 times; for CH4, 2.36 times; for N2, 3.08 times). In turn, the greatest increase in selectivity was obtained for the CO2/CH4 mixture for the membrane containing 5 wt% SiO2 (1.15 times), and for the CO2/N2 mixture for the membrane containing 2 wt% POSS-Ph (1.21 times). [ABSTRACT FROM AUTHOR]

Polymeric micelle forming from self-assembly of amphiphilic macromolecules is one of the most potent drug delivery systems. Fatty acids, naturally occurring hydrophobic lipid components, can be considered as potential candidates for the fabrication of block copolymer micelles. However, examples of synthesis of responsive block copolymers using renewable fatty acids are scarce. Herein, we report the synthesis, characterization and testing of block copolymer micelles composed of a renewable fatty-acid-based hydrophobic block and thermoresponsive hydrophilic block for controlled drug delivery. The block copolymers of functionalized fatty acid and poly(N-isopropylacrylamide) (PNIPAM) were prepared via consecutive microwave-assisted reversible addition fragmentation chain transfer (RAFT) polymerization. The block copolymers with variable hydrophobic block length self-assembled in aqueous media and formed spherical nanoparticles of ~30 nm with low critical micelle concentration (CMC). To demonstrate the proof-of-concept, carbamazepine (CBZ) was used as a hydrophobic model drug to evaluate the performance of these micelles as nanocarriers. The in vitro drug release tests were carried out below (25 °C) and above (37 °C) the lower critical solution temperature (LCST) of the block copolymer. The drug release showed obvious temperature-triggered response and an accelerated drug release at 37 °C. [ABSTRACT FROM AUTHOR]

A novel series of linear, high molecular weight aromatic copolymers containing trifluoromethyl and dimethylamino groups was synthesized via facile super-acid catalyzed polyhydroxyalkylation and investigated as CO 2 gas separation membrane materials. The molar ratio of the two ketone comonomers used in copolymerization, trifluoroacetophenone (TFAp) and N,N-dimethylamino trifluoroacetophenone (dMATFAp), was systematically varied to produce five copolymers with different dMATFAp contents ranging from 12 to 73 %. The influence of dMATFAp content on physicochemical and mechanical properties as well as pure gas and water vapor separation performance was studied. All synthesized copolymers displayed excellent film forming ability, high thermal stability and high T g values (T gs > 380 °C). Pure gas permeability measurements revealed that the increase of dMATFAp molar content from 12 % to 34 % resulted in improved gas permeability, while, on the contrary, further increase of dMATFAp content from 34 to 73 % led to substantial gas permeability decrease ascribed to FFV decrease. In particular, among copolymers, the one with dMATFAp content of 34 % presented the highest CO 2 permeability value of 290 Barrer due to its highest CO 2 diffusion and CO 2 solubility coefficients associated with its higher FFV value. The CO 2 /CH 4 performance of synthesized copolymers fell very close to 2008 upper bound limit and exceeded most of the super-acid catalyzed copolymer membranes reported in the literature and commercial membranes. CO 2 /CH 4 and CO 2 /N 2 selectivity values for the different synthesized copolymers were in the range of 29.9–40 and 22.7–44, respectively. The study of the effect of dMΑTFA on water permeability unveiled that the membrane with the highest dMΑTFAp molar content (73 %) showed the highest water permeability value (23,100 Barrer) as well. This was attributed to the increased concentration of N-methyl substituent of dMΑTFAp which can interact with water molecules thereby increasing solubility. Under process gas stream conditions using a mixture of 3 % H 2 O-48.5 % CO 2 -48.5 % CH 4 , both CH 4 and CO 2 permeability were significantly reduced (by 35 % and 47 %, respectively) due to the preferential sorption of water vapor over other gases present in the mixture, highlighting the negative effect of water vapor on gas permeability. Accordingly, the CO 2 /CH 4 separation factor was slightly increased from 23.8 to 29. Finally, stability test of the copolymer (BP-TFAp) 66 -(BP-dMATFAp) 34 at 40 °C under humid mixed gas conditions showed that CO 2 and CH 4 permeability remained unchanged for one month after an initial condition stabilization that is required implying that these copolymer structures are promising materials for CO 2 separation. [Display omitted] • Novel high molecular weight fluorinated main chain ether-free aromatic copolymers. • Synthesis of copolymers via room temperature, non-stoichiometric super-acid hydroxyalkylation. • The copolymer with optimal dMATFAp content of 34 % shows the highest CO 2 permeability. • A sufficient number of –N(CH 3) 2 lateral groups enables the CO 2 solubility and CO 2 diffusion coefficients increase. • Excellent anti-aging performance under humidified gas mixture conditions at 40 °C for one month. [ABSTRACT FROM AUTHOR]

The main focus of the present research is to design network hydrogels derived from natural polymers to promote a sustainable future. Multifunctional hydrogels were prepared by combining sterculia gum (SG), phosphorester -cyclic amide polymers for bio-medical applications including drug delivery (DD). The antibiotic drug ceftriaxone was incorporated into hydrogels to enhance wound healing potential. The surface morphology of copolymers was investigated by using FESEM and AFM techniques. FTIR and 13C NMR spectroscopic techniques provided insight into the formation of network structures. In FTIR analysis, distinctive bands were identified: at 1649 cm−1 attributed to C O stretching of the cyclic amide of PVP, at 1147 cm−1 and 974 cm−1 representing P O stretching and P-O-C of poly(BMEP), respectively. In the 13C NMR spectrum, a prominent peak at 63.272 ppm revealed the presence of (O-CH 2) linkage of poly(BMEP). XRD demonstrated amorphous characteristics of hydrogels. The interactions of copolymer with blood, bio-membrane and encapsulated drug illustrated their biocompatibility, bio-adhesion and controlled DD properties. The dressings expressed a hemolytic index value of 2.58 ± 0.03 %. The hydrogels exhibited mucoadhesive character, revealed from the adhesion force of 50.0 ± 5 mN needed to separate polymer dressing from the mucosa. Dressings exhibited antioxidant properties and displayed 33.73 ± 0.3 % radical scavenging in the DPPH assay. Protein adsorption test of copolymer illustrated 9.48 ± 0.970 % of albumin adsorption. The tensile strength of the dressing was found 0.54 ± 0.03 N mm−2 while the burst strength 9.92 ± 0.27 N was observed. The sustained release of the drug was provided by supra-molecular interactions. Drug release followed a non-Fickian diffusion mechanism and the release profile was best described by the Higuchi kinetic model. Additionally, hydrogel dressings revealed permeability to H 2 O vapors and O 2 and antimicrobial activity. These findings suggest the suitability of sterculia gum-based hydrogels for DD uses. [ABSTRACT FROM AUTHOR]

Self-doped- and nitro-polyanilines have become a widely used strategy to optimize the electronic and vibratory spectra of polymeric building blocks in various applications. We report the synthesis of poly (5-nitro-2-orthanilic acid) by an aniline-initiated oxidative polymerization reaction. The polymer is characterized by spectroscopic techniques, elemental shapes, cyclic voltammetry, electrical conductivity, and microscopic and thermal measurements. The hydrophilic and hydrophobic nature of the supports provided the formation of amphiphilicity as judged by SEM. Thermogravimetric measurements reveal thermal stability up to 500 °C and glass temperature (Tg) observed at 240 °C. Electrical conductivity decreases as the temperature rises at the different frequencies used, reflecting the semiconducting nature in the extrinsic range, which is characterized by high carriers and low mobility. The presence of these electron residues causes a decrease in efficiency and increases the thermal conductivity. Dielectric measurements have shown that permittivity decreases gradually at lower levels, mainly due to the transport of charging carriers, resulting in higher performance. The testing of the copolymer as a new scale blocker has resulted in moderate to fairly high performance. This effect is attributed to the change in polymer geometry using intramolecular H-bonding group -SO3H and a chain polymer in an aqueous medium. [ABSTRACT FROM AUTHOR]

Sensitivity toward humidity, response and recovery time, and reproducibility behaviors of a novel copolymer sensor, obtained by oxidative chemical polymerization of o-phenylenediamine and aniline using D-camphor-10-sulfonic acid dopant, were reported. It is a novel copolymer, and there are very few studies available concerning its synthesis and humidity sensing applications. Humidity-sensitive properties of the copolymer were tested by measuring the resistance of the fabricated films, and good humidity sensitivity was obtained. Moreover, a decrease in resistance with the increase in humidity was observed. Compared to polyaniline (PANI), the humidity sensing property of the copolymer was found to show quicker response and recovery time, higher reproducibility, and higher sensitivity. However, PANI alone exhibited relatively poor sensing property. The response time for the copolymer films at the relative humidity ranging from 11 to 97% was about 38 s, and the corresponding recovery time was about 11 s. The value of sensitivity was about 10. These results indicate excellent sensing character of the new type of copolymer humidity sensors. The obtained sensor is expected to exhibit good humidity sensing behavior in moisture-containing environment. [ABSTRACT FROM AUTHOR]

Size‐dependent antimicrobial ability of silver nanoparticles (Ag NPs) supported by amino‐functionalized poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (poly(GMA‐co‐EGDMA)) macroporous copolymer was tested against Gram‐negative bacteria Escherichia coli. Inorganic/organic hybrids with distinctly different average sizes of Ag NPs (6.6 and 12.1 nm) were prepared by functionalization of poly(GMA‐co‐EGDMA) with either 1,8‐diaminooctane or ammonia, and consequent reduction of silver ions with amino groups. The transmission electron microscopy (TEM), infrared and UV–Vis reflection spectroscopy, elemental analysis, and inductively coupled plasma atomic emission measurements were used to characterize synthesized hybrid materials. Time‐ and concentration‐dependent antimicrobial performances of prepared samples revealed higher reduction rates of E. coli when hybrid with smaller in size Ag NPs was used. The difference between rates of reduction of E. coli for different size Ag NPs is becoming more pronounced by decrease of the concentration of silver. POLYM. COMPOS., 40:2901–2907, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The effects of the structure of di- and triblock copolymers of poly(L-lysine) - LYS with poly(ethylene glycol) - PEG as well as the length of nonionic fragment in the LYS-PEG macromolecule on the copolymer chains conformation in the adsorption layer formed on the colloidal silica (SiO2) surface were examined. Spectrophotometry and turbidimetry were applied for the determination of copolymer adsorbed amounts and stability coefficients of silica aqueous suspensions. The electrokinetic parameters such as solid surface charge density and zeta potential were also estimated. The adsorption of LYS-PEG was proved to be the highest at pH 10 whereas the lowest adsorption on the solid surface was found for the triblock copolymer with long fragments of LYS at the same pH value. [ABSTRACT FROM AUTHOR]

The effects of different types (red, black and blue color) and content (2% and 4%) of thermochromic powders on aging properties of styrene-butadiene-styrene copolymer (SBS) modified asphalt were investigated. Physical properties of the binders (ductility, penetration, viscosity and softening point) were tested before and after thermal-oxidative and ultraviolet radiation aging. The results showed thermochromic powders improved the deformability and weakened the high-temperature performance of SBS modified asphalt to some extent. Thermochromic powders could obviously improve the anti-aging properties of SBS modified asphalt. In addition, SBS modified asphalt with 2% thermochromic materials showed the best aging resistance under all aging modes. [ABSTRACT FROM AUTHOR]

Highlights • Cationic lignin-acrylamide was used as a flocculant for clay suspension. • Molecular weight of copolymers affected physicochemical properties of suspensions. • The impact of the copolymer on floc strength was evaluated. • pH of the suspension affected the performance of cationic lignin-acrylamide. Abstract Currently, kraft lignin is burned in the recovery cycle of the kraft pulping process; despite its high potential to be extracted and converted into value-added products. In this work, kraft lignin (KL) was copolymerized with acrylamide (AM) and 2-[(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) to produce cationic copolymers. Copolymers with two different molecular weights of 168,200 g/mol (KAD-1) and 103,000 g/mol (KAD-2), but with a similar charge density of 1.15 meq/g, were selected and the flocculation efficiency of the copolymers in two different clay suspensions was investigated. Suspension pH affected the adsorption of the copolymers on clay particles and the removal of the particles from the suspension. At a 8 mg/g dosage, KAD-1 adsorbed more than KAD-2 as it was larger and thus developed more bridging with clay particles. The size of particles raised from 4.7 for kaolin to 16.3 μm for kaolin/KAD-1 flocs and 15.1 μm for kaolin/KAD-2 flocs, and it increased from 6.1 for bentonite to 18.97 μm for bentonite/KAD-1 flocs and 15.35 μm for bentonite/KAD-2 flocs in the presence of 8 mg/g of copolymers, respectively. The adsorption, zeta potential and flocculation analyses confirmed that KAD-1 was a more effective flocculant than KAD-2. The evidence for the agglomeration of clay particles via bridging and electrostatic patch mechanisms was also discussed in this work. [ABSTRACT FROM AUTHOR]

The stimuli‐responsive supramolecular co‐assembly of two π‐amphiphiles, NDI‐1 and Py‐1, in which an acceptor (A) (naphthalene diimide) and a donor (D) (pyrene) chromophore, respectively, serve as the hydrophobic segment, is described. In addition, both contain an amide group in a designated location so that H‐bonding and D–A charge‐transfer (CT) interactions can operate simultaneously. H‐bonding among the amide groups not only enhanced the CT interaction promoted by the alternating D–A stacking propensity, but also fixed the lateral orientation of the two chromophores and thus compelled the anionic and nonionic hydrophilic head groups, appended with the D and A amphiphiles, respectively, to remain segregated on two opposite sides of the amphiphilic alternating supramolecular copolymer. This copolymer showed spontaneous polymersome assembly with the D‐appended anionic groups displayed at the outer surface, whereas the A‐appended hydrophilic wedge converged at the inner lacuna. In contrast, spherical or cylindrical micellar structures were produced by Py‐1 and NDI‐1, respectively. Effective functional‐group display in the D–A supramolecular polymersome enabled protein‐surface recognition and inhibition of the enzymatic activity of Cht. Under a reducing environment, formation of NDI.− jeopardized the D–A interaction and thus the A chromophores were ejected out of the membrane of the polymersome causing its gradual contraction in size by >75 %. D–A supramolecular polymersomes also exhibited a lower critical solution temperature that could be tuned across a temperature window of 40 to 70 °C by varying the ratio of the A and D components in the alternating supramolecular copolymer. H‐bonding promoted directional alternating donor–acceptor stacking leads to formation of a multi‐stimuli‐responsive supramolecular polymersome with the desired functional‐group display (see scheme). In contrast, the individual components form a micelle and hydrogel, respectively. [ABSTRACT FROM AUTHOR]

Two types of random copolymer poly(d-lactideco- ε-caprolactone) (PDLA-r-PCL) were added into poly(llactide) (PLLA) matrix by melt blending. The structure and property of PLLA/PDLA-r-PCL blends were investigated by thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, wide-angle X-ray diffraction, and mechanical measurement. The results suggested that PDLA-r-PCL had little effect on the thermal property of PLLA. PDLA-r-PCL uniformly dispersed in PLLA matrix, which contributed to the improvement of stretching properties. During stretching at 25°C, with the increased content of PDLA-r-PCL, the elongation at break of PLLA increased and the strength decreased. The degree of decrease in fracture strength was related to the molecular structure of PDLA-r-PCL. When a small amount of stereocomplex crystals (SC) were formed in PLLA/PDLAr- PCL blends, the strength was maintained or slightly enhanced even though the elongation at break of the blends was significantly improved by soft chains of PCL. It might be caused by the synergistic effects of SC crystals and plasticization of PCL chains. [ABSTRACT FROM AUTHOR]

Hypothesis The microfluidic technology can drive molecules to organize into aggregates with nano-structures, and gives a possibility to control aggregate morphologies by adjusting hydrodynamic parameters of microfluidics. COMSOL Multiphysics is a useful software to simulate the mixing situation of solutions in microfluidic. Here, experiments and simulation are combined to study the self-assembly of gradient copolymers in the microfluidic device. Experiments Fluorinated gradient copolymers self-assembled in a three-dimensional co-flow focusing microfluidic device (3D CFMD). Hydrodynamic parameters of 3D CFMD were adjusted to control morphologies and the sizes of copolymer aggregates. A simulation software, COMSOL Multiphysics, was used to simulate the mixing and diffusion of outer phase stream and inner phase stream to explore the mixing kinetics of two streams in the microchannels. Findings 3D CFMD offered a novel platform for the continuous and controllable self-assembly of fluorinated gradient copolymer. Various morphologies of copolymer aggregates were obtained in 3D CFMD, but just spherical micelles were formed by a traditional solvent-inducing method. The flow velocity, initial water content of outer-phase stream, and the copolymer concentration of inner-phase stream had great effects on the morphology and size of copolymer aggregates. The simulation results made us a better understanding on the microfluidic self-assembly. [ABSTRACT FROM AUTHOR]

Abstract: Simple, versatile, efficient, and readily scalable chemical routes using epoxy‐containing copolymers to achieve complex polymeric structures exhibiting desired chemical functionalities are demonstrated. As proof of concept, Janus nanofiber mats are fabricated. As epoxide groups in the copolymer can react with various nucleophiles such as amine, alcohol, and thiol, single‐side functionalization with a primary amine containing dopamine by floating on an aqueous dopamine solution is shown. The other side can be further modified with thiol‐containing molecules via thiol–epoxy click chemistry, elucidating effectiveness of copolymer as a versatile toolbox to impart desirable functionalities toward a variety of surfaces. [ABSTRACT FROM AUTHOR]

Low thermal stability and the shortage of core leakage strongly limit the application of conventional energy storage microcapsules. This study focuses on a novel strategy to develop a new phase change material with excellent thermal durability without core leakage. The new phase change materials is a P(BeA-co-MMA) copolymer microcapsule with crystalline n -alkane side chains. Under the protection of polymer main chains as the shell or skeleton structure on a nano-scale, the crystalline side chains as the core will no longer suffer loss and will maintain stablity in use. The chemical composition, inner homogeneous structure, thermoregulation properties, crystalline behaviour and thermal stability are discussed. The P(BeA-co-MMA) microcapsules provide energy storage capacity in the temperature range of 48–62 °C with the highest enthalpy of 105.1 J g −1 . The 5% weight loss temperature ( T 5% ) is more than 315 °C, which is high enough to withstand the general polymer processing temperature to open the possibility of developing energy storage modified fibre and polymer materials as functional fillers. [ABSTRACT FROM AUTHOR]

A series of high-performance polyimide copolymer (co-PI) fibers containing phenylenebenzoxazole moiety with one hydroxyl group are synthesized based on the copolymerization of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) with two diamine monomers, namely, p -phenylenediamine ( p -PDA) and 5-anino-2-(2-hydroxy-4-aminobenzene)-benzoxazole ( p -mHBOA), through a two-step method. The molar ratio of p -PDA/ p -mHBOA varies from 10/0 to 0/10. Influences of the p -mHBOA moieties on the thermal stability, crystal structure, crystal orientation, microvoid morphology, and mechanical properties are systemically investigated. Fourier transform infrared results confirm that intra/inter molecular hydrogen bonds come from the OH group and nitrogen atom of the benzoxazole group and/or OH group and the oxygen atom of the carbonyl group of cyclic imide. The glass transition temperatures ( T g s) of co-PI fibers are in the range of 290 °C–325 °C. The prepared fibers show excellent thermal stabilities, and their T 5% is within 528 °C–542 °C in air. Two-dimensional wide-angle X-ray diffraction spectra indicate that homo-PI and co-PI fibers present a regularly arranged polymer chains along the fiber axial direction. Moreover, the ordered molecular packing along the transversal direction of fibers is destroyed by the copolymerization. Small-angle X-ray scattering results show that co-PI fibers with optimal mechanical properties exhibit the shortest average length ( L ) and the smallest radius ( R ¯ ) of microvoids. When the p -mHBOA/ p -PDA molar ratio is 5/5, the fracture strength and initial modulus can reach approximately 30.31 cN/dtex (4.40 GPa) and 894.88 cN/dtex (129.8 GPa), respectively. The relationship between structure and mechanical properties is also discussed. [ABSTRACT FROM AUTHOR]

Crosslinked poly(urea-siloxane) (PUS) copolymer microspheres with diameters ranging from 0.8 to 1.8 μm with diameter polydispersity indices between 1.15 and 1.60 were synthesized in one-step precipitation polymerization in water-acetone solvent mixtures at room temperature. The spheres were obtained using aminopropyl-terminated siloxanes, isophorone diisocyanate and a tetrafunctional isocyanate crosslinker, employing a systematically varied molar ratio. The length of the siloxanes was controlled to obtain spheres with pre-determined Young's modulus values. Phase separation between soft disiloxane/poly(dimethylsiloxane) segments and hard isophorone bisurea units was observed with an excellent spatial resolution of ∼5 nm using atomic force microscopy (AFM). AFM mapping of the Young's modulus was achieved utilizing the PeakForce Quantitative Nanomechanical Mapping (QNM) mode. This AFM method allowed us to also measure the values of elasticity moduli of individual microspheres, ranging from 200 to 900 MPa. The microspheres can be used as filler to fine-tune the properties of composite materials, particularly with regard to elasticity. The hydrophobicity was also varied as indicated by water contact angle values between 122° - 132°. These features open the possibility of preparing designer composites for a range of applications from coatings to the biomedical field. [ABSTRACT FROM AUTHOR]

Poly (ethylene-vinylalcohol) copolymer (EVOH) films under different humidity conditions were studied by THz absorption spectroscopy to obtain information about the bound water. An intermolecular stretching mode of bound water was observed at around 6 THz, similar to that in liquid water; and the very weak libration mode indicates that this water is frozen. By generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation 2D moving window (PCMW2D) correlation spectroscopy, the bound water was categorized into three types: frozen with amorphous structure (I), liquid-like with librational motion (II), and nearest neighboring water with weaker hydrogen bonding network (III). The strongly inhomogeneous intermolecular stretching band of water I shows that the frozen bound water is amorphous. The frequency shift of this band in water III indicates a weaker hydrogen bonding network around the ethylene group. Changes in the films' oxygen permeability are discussed and correlated with the dynamics of bound water. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to prepare a series of PVdF-co-HFP based electrolytes with different LiClO4 loadings and to investigate their chemical and electrical properties in detail. For this purpose, PVdF-co-HFP based electrolytes with different LiClO4 loadings (1-20 weight %) were prepared using solution casting method. X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric (TGA) -differential thermal and dielectric spectroscopy analysis of PVdF-co-HFP/LiClO4 were performed to characterize their structural, thermal, and dielectric properties, respectively. XRD results showed that the diffraction peaks of PVdF-co-HFP/LiClO4 electrolytes broadened and decreased with LiClO4. TGA patterns exhibited that PVdF-co-HFP/LiClO4 electrolytes with 20 wt % of LiClO4 had the lowest thermal stability and it degraded above 473 K, which is highly applicable for solid polymer electrolytes. Dielectric constant, dielectric loss, and conductivities were calculated by measuring capacitance and dielectric loss factor of PVdF-co-HFP/LiClO4 in the range from 10 mHz to 20 MHz frequencies at room temperature. In consequence, conductivities of PVdF-co-HFP/LiClO4 increased significantly with frequency for low loading of LiClO4 while they only slightly changed with higher LiClO4 addition. On the other hand, dielectric constant values of PVdF-co-HFP/LiClO4 films decreased with frequency whereas they rose with LiClO4 addition. The dielectric studies showed an increase in dielectric constant and dielectric loss with decreasing frequency. This result was attributed to high contribution of charge accumulation at the electrode-electrolyte interface. The electrolyte showed the maximum conductivity of 8 × 10−2 S/cm at room temperature. [ABSTRACT FROM AUTHOR]

Woven fabric is composed of two yarns system, known as the weft and warp yarns. Each yarn system has an effect on the physical, performance, and optical properties of fabric. Any change in one or both yarn systems greatly alters the fabric properties. The solar and luminous properties of fabrics are also affected by altering the weft yarn or both yarn systems. This study investigates the effect of altering the weft yarn system on the solar and luminous properties of fabrics. The differences in the weft yarn in the fabrics were based on the weft yarn structure, including the yarn linear density, amount of twist on the yarn, yarn evenness, hairiness, spinning method, fiber composition of the yarn, and weft density of the fabric. The fabric luminous and solar properties were measured according to EN 14500 using an ultraviolet-visible-near-infrared (UV/VIS/NIR) test device and calculated from the EN 410 standard test method. According to a variance analysis, the weft density factor is shown to have an effect on the solar properties of the fabric, especially the UV transmittance properties of the fabric. Although non-parametric test results with a 95% confidence level show that the yarn structure does not influence the solar characteristics of the fabric, we show from the test results that the yarn structure influences the solar properties of the fabric. Yarn hairiness was the dominant factor for the IR and visible portions of the solar radiation spectra. In the UV region, the fiber composition factor was found to be important. The effect of the yarn linear density was similar to the effect of the weft density factor. The solar transmittance decreases and the reflectance increases when the number of weft yarns per unit length is increased and the yarn linear density in the Ne numbered system is decreased. Increasing the yarn hairiness decreases the transmittance in the IR portion of the solar spectra. The degree of influence that the yarn structure has on the solar properties (with the exception of the UV portion) of the fabric was dominated by the number of weft yarns per unit length. The transmittance properties of the fabric were more affected by altering the yarn structure than the reflectance and absorbance properties. [ABSTRACT FROM AUTHOR]

Various multiple-attribute decision analysis approaches have been developed to choose the best fashion design among alternatives, but none of them consider interdependence among their criteria. This study combined the diamond pairwise comparison method to elicit the weights and interaction degrees of a set of criteria and the Choquet integral method for aggregating the evaluation to identify the best design based on the decision-makers’ preferences and prospects. The criteria were determined from input by 10 experts in diverse areas related to fashion design. By implementing the hybrid method in a case example, the efficacy of the proposed approach for evaluating fashion designs is demonstrated. [ABSTRACT FROM AUTHOR]

The stent-graft has always been a key device in endovascular treatments. However, most stents are integrated with graft by sutures, which may fracture or untie, leading to implant failure. This study reports a new sutureless composite stent-graft fabricated by braiding technology, which can combine various materials. The proposed sutureless braided stent-graft was constructed by incorporating bare/covered nitinol (NiTi) yarns into a polyethylene terephthalate multifilament at specific distributions. This technique generates a structure with alternately arranged metal and polymeric sections that equip the stent-graft with structural support and flexibility, respectively. The results showed significantly improved biomechanical performance (radial compression, bending and torsion resistance) of the stent-graft with covered NiTi yarns compared to bare NiTi yarns. This research presents important clinical implications in stent-graft manufacture and provides further study with an innovative stent-graft design. [ABSTRACT FROM AUTHOR]

The industry uses color masterbatch mixing process and spinning for dope dyeing. There are color mending and color passivation appearance problems, and the process is inapplicable to functional apparel textiles. In this study, dyeable modified polypropylene (PP) fabric with disperse dye will be developed. The modified polyester material and PP for compounding processing with a compatibilizer will be used to make chips and the quality engineering method will be applied to analyze the optimum spinning process parameters. The fabric will be used to validate the dye washing fastness and light fastness in order to implement the dyeability of PP modified disperse dye. The optimum processing parameters to develop dyeable PP fiber will be studied. The modified materials are made into fiber by melt spinning, and the fuzzy C means technique is combined with the stem cells algorithm to design and analyze the processing parameters for the quality characteristics of tensile strength and elongation. The optimum fully drawn yarn is made. The tensile strength of the fiber of optimum parameter design is 3.66 g/d, higher than the 3.36 g/d of the pure PP fiber; the elongation is 38.65%, higher than the 36.66% of pure PP fiber, meaning the optimization method could improve the characteristics in melt spinning process, and conform with the standards of the textile industry. The fiber derived from the optimum parameters is woven into fabric for the disperse dyeing test and the validation of washing fastness shows the washing fastness is Level 3–4, meaning that the developed modified PP fabric has good dye-uptake and fastness. [ABSTRACT FROM AUTHOR]

The melt spinning of cellulose acetate butyrate (CAB) without any additives is realized according to the thermal and rheological properties of cellulose acetate butyrate raw material. Thermogravimetric analysis reveals that thermal degradation of cellulose acetate butyrate occurs at 275℃ in oxygen. Rheological tests show that cellulose acetate butyrate is a strong shear thinning pseudoplastic fluid. The melt viscosity of cellulose acetate butyrate is found to be relatively sensitive to temperature change and cellulose acetate butyrate melt is difficult to flow until the temperature reaches 230℃. However, thermal degradation of cellulose acetate butyrate during spinning cannot be completely avoided even when the spinning temperature is 230℃. The orientation of cellulose acetate butyrate fibers can be improved by increasing the spinning draw ratio during the spinning process or by hot drawing during the drawing process. Crystallization of cellulose acetate butyrate fibers is facilitated by improving molecular orientation. Owing to the improved orientation and crystallinity, the tensile strength and initial modulus of cellulose acetate butyrate fibers are enhanced. The cellulose acetate butyrate fiber achieves the highest degree of orientation and crystallinity by drawing at 135℃, showing the highest tensile strength at 1.42 cN/dtex. Moreover, dyeing experiments show that the cellulose acetate butyrate fiber can be dyed with a disperse dye and the suitable dyeing temperature is in the range of 80∼90℃. [ABSTRACT FROM AUTHOR]

A method to prepare a kind of wet-laid nonwoven fabric that can be used in microwave absorbing honeycomb is proposed. It was prepared through a papermaking process with carbon fiber (CF) and poly-p-phenylenebenzobisoxazole (PBO) fibrillated pulp. Fibrillated PBO pulp has a large surface area and lots of micro-fibrils which is beneficial for the uniformity and mechanical strength of the wet-laid nonwoven fabric. The electromagnetic properties and absorbing performances of the wet-laid nonwoven fabric with different content of CF were compared. The results showed that the complex permittivity increased when the content of the CF increased, and then decreased when the content was higher than 10 wt%. The resistivity measured by four probe testers decreased with the increase of the content of CF. Calculated by the measured complex permittivity and permeability, the CF/PBO wet-laid nonwoven fabric had a lowest reflection loss of -27.60 dB at a content of 20 wt%, with an optimum thickness of 1.72 mm. [ABSTRACT FROM AUTHOR]

This work investigated the cyclization possibility and melt spinnability of carbon fiber precursors, poly(acrylonitrile-co-methyl acrylate) (AN/MA) and poly(acrylonitrile-co-dimethyl itaconate) (AN/DMI). The onset temperature of cyclization of the AN/DMI copolymer is lower than that of the AN/MA copolymer and also the polyacrylonitrile (PAN) homopolymer. The enthalpy (ΔH) of the AN/DMI copolymer is about 3–4 times that of the PAN homopolymer and about 1.8 times that of the AN/MA copolymer, indicating that the degree of cyclization of the AN/DMI copolymer is relatively higher. The melt dwell time of the AN/DMI copolymer is increased to about 3–5 times that of the AN/MA copolymer, especially when synthesized with a feed molar ratio of AN/DMI = 85/15. The AN/DMI copolymer (AN/DMI = 85/15) has the longest melt dwell time, 24.8 min, at the lowest melting temperature, 190oC, among all the PAN-related copolymers synthesized herein. Furthermore, the AN/DMI copolymer (AN/DMI = 85/15) can be rapidly cyclized at the cyclization temperature of 260℃, which is 25℃ lower than that of the AN/MA copolymer (AN/MA = 85/15). In short, this work demonstrates that the carbon fiber precursor made by the AN/DMI copolymer (AN/DMI = 85/15) will be superior to that of the AN/MA copolymer (AN/MA = 85/15) with respect to the melt spinnability and cyclization at low temperature. [ABSTRACT FROM AUTHOR]

ABSTRACT: Conducting composite materials, with electrical percolation threshold as low as 0.05–0.08 wt %, are prepared by incorporating multiwall carbon nanotube (CNT) in melt‐mixed co‐continuous polystyrene (PS)/ethylene‐vinyl acetate (EVA) copolymer (70:30 wt/wt) blend. CNT is found to be preferentially localized within the EVA phase, characterizing a double percolation phenomenon, which accounts for outstanding electrical conductivity (around 0.5 S/m with the addition of 1 wt % of CNT). The noncovalent functionalization of CNT with alkylphosphonium‐based ionic liquid results in composites with improved electrical conductivity (2.5 S/m with 1 wt % of CNT) and better electromagnetic interference shielding effectiveness. Both nonfunctionalized CNT (n‐CNT) or CNT with alkylphosphonium‐based ionic liquid contribute for a refinement of the co‐continuous structure, as indicated by scanning electron microscopy. The dispersion of CNTs and their physical networked structure within the polymer matrix are suggested by transmission electron microscopy and melt rheological experiments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45564. [ABSTRACT FROM AUTHOR]

A series of new hybrid donor-acceptor materials based on hexabenzocoronenes (HBC) functionalized with electron donors is investigated by combining a variety of quantum mechanical and molecular dynamic methodologies for use in organic photovoltaic (OPV) devices. Segments of a low band gap alternating copolymer constructed of benzo[1,2- b ;3,4- b ]dithiophene and thieno[3,4- c ]pyrrole-4,6-dione were attached to the conjugated HBC core. The copolymer was chosen for its known high performance in OPVs, and both moieties were singled out due to their exceptional resistance to photo-oxidation, an important requirement for such applications. The macromolecular topology of these systems are expected to induce supra-molecular columns, such as those common to discotic liquid crystals, conducive to the effective percolation of electrons in OPV devices. A challenge with these systems, that of the mixing of the electronic structures of the donor and acceptor moieties that result in excitonic losses and charge recombination, was diminished by trialling a range of linking units. It was found possible to propose ideal donor-acceptor structures with enhanced charge dissociations and transfers in the π -stacking direction for use in OPV and other organic electronic devices. [ABSTRACT FROM AUTHOR]

Mixed-ligand metal-polymer complexes (MPC) of N-vinylpyrrolidone-N-vinylformamide-N-vinyl iminodiacedic acid (VP-VFA-VIDA) copolymers and diethyldithiocarbamate (DEDTC) as a co-ligand with indium were synthesized under mild conditions and pH close to physiological values. Isolated MPC were characterized by UV, IR, 1H NMR, atomic absorption spectrophotometry, and HPLC. The obtained data implied that the MPC contain 8-10 wt% of (IDA)In(DEDTC) fragments. The optimal conditions for radiochemical synthesis of VP-VFA-VIDA-111In-(DEDTC) metal-polymer complex with mixed ligands were defined. The closest coordination environment of 111In was studied by perturbed angular correlation technique. The obtained data are in good agreement with the information about weight amounts of the corresponding indium MPC. [ABSTRACT FROM AUTHOR]

Abstract: Two new wide‐bandgap D–A–π copolymer donor materials, PBDT‐2TC and PBDT‐S‐2TC, based on benzodithiophene and asymmetric bithiophene with one carboxylate (2TC) substituent are synthesized by a facile approach for fullerene‐free organic solar cells (OSCs). The combination of one carboxylate‐substituted thiophene with one thiophene bridge in the backbone substantially reduces the steric hindrance, thereby favoring a planar geometry for efficient charge transport and molecular packing. A reasonable highest‐occupied‐molecular‐orbital energy level in relation to that of the acceptor and balanced hole and electron transport are observed for both polymers. This asymmetric structure unit is flexible and versatile, allowing the absorption, energy levels, and morphology of the blend films to be tailored. Fullerene‐free OSCs based on PBDT‐S‐2TC:ITIC achieve a high power conversion efficiency of 10.12%. More impressively, a successful nonhalogen solvent‐processed solar cell with 9.55% efficiency is also achieved, which is one of the highest values for a fullerene‐free OSC processed using an ecofriendly solvent. [ABSTRACT FROM AUTHOR]

We report a blue-emitting random copolymer (termed modified Aryl-F8) consisting of three repeat units of polydioctylfluorene (F8), Aryl-polydioctylfluorene (Aryl-F8), and an aromatic amine comonomer unit, poly(bis-N,Ν′-(4-butylphenyl)-bis-N,N′-phenyl-1,4 phenylenediamine) chemically linked to get an improved charge carrier balance without compromising on the photoluminescence (PL) quantum yield with respect to the Aryl-F8 homo-polymer. The measured photoluminescence quantum efficiency (∼70%) of the blue-emitting polymer is comparable to or greater than the individual monomer units. The time resolved PL spectra from the modified Aryl-F8 are similar to those of Arylated-poly(9,9′-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenyl-1,4 phenylenediamine) (PFB) even at a time scale of 100–250 ps, indicating an ultrafast energy transfer from the (Aryl-F8 or F8):Arylated-PFB interface to Arylated-PFB, i.e., endothermic transfer of non-radiative exciplex to a radiative molecular exciton. Furthermore, the presence of non-radiative exciplex is confirmed by the photoluminescence decay profile and temperature dependent PL spectra. The luminance efficiency achieved for the modified Aryl-F8 polymer light-emitting diodes is ∼11 cd A−1 with an external quantum efficiency (EQE) of ∼4.5%, whereas it is 0.05 cd/A with an EQE of ∼0.025% for Aryl-F8. Almost two orders of higher efficiency is achieved due to the improved charge carrier balance from the random copolymer without compromising on the photoluminescence yield. [ABSTRACT FROM AUTHOR]

Biobased thermoplastic elastomers are of interest for their merits, especially renewability and sustainability. In this work, a series of fully biobased linear comb poly(β-myrcene)- graft -poly( l -lactide) (PM- g -PLLA) copolymers consisting of interior rubbery block and exterior semicrystalline block were synthesized via ring-opening polymerization of l -lactide using hydroxylated poly(β-myrcene) as macroinitiator. To evaluate the effects of branch length and graft density of poly(β-myrcene) on the performances of these obtained copolymers, the chemical compositions and molecular weights, crystal structures and spherulite morphologies, phase morphologies, thermal and mechanical properties were systematically analyzed by various techniques. Analysis of NMR and GPC indicated that graft copolymers were successfully obtained as designed. Two distinct glass transitions corresponding to the two building blocks observed from both DMA and DSC measurements suggested the occurrence of microphase separation, which was further confirmed by SAXS and AFM morphological characterizations. Results of DSC, WAXD, and POM showed that the crystallization behavior of the graft copolymers depends on graft density and branch length. Tensile test suggested that the mechanical properties of graft copolymers depend on PM/PLLA composition, particularly graft density and branch length, which could be readily tailorable to different applications. [ABSTRACT FROM AUTHOR]

The solvent evaporation has been identified able to induce the cocrystallization of dissolved polyvinylidene fluoride (PVDF) homopolymer and poly(vinylidene fluoride trifluoroethylene) (PVDF-TrFE) copolymer solutes in this research. Upon the random incorporation of either trifluoroethylene (TrFE) or vinylidene fluoride (VDF) motif during this selected route of cocrystallization, several ferroelectric crystalline phases grow concurrently. For the development of each crystalline form, there is an appropriate composition range of TrFE motif, instead of a specific composition. When the inclusion of TrFE is beyond a threshold level, the non-polar HT-form crystals were found to solely develop upon slow heating above Curie temperature, and therefore inherits various compositions of TrFE motif. During the stay above Curie temperature, stick-like HT-form lamellar cocrystals preferably associate together and coalesce into coarser crystalline lamellae. This coalescence behavior is deduced to be driven by the secondary crystallization above Curie temperature, presumably enabled by the acceptable level of lattice-packing entropy of HT-form cocrystals. During the subsequent cooling below Curie temperature, the coalesced HT-form lamellar cocrystals reversely split into thinner lamellar cocrystals with various types of ferroelectric lattice packing comprising narrower ranges of TrFE composition. The Curie transition of cocrystals is thus accompanied with the alteration of the stacking dispersion of crystalline lamellae within materials, which associates with the variation of motif composition and therefore the lattice-packing entropy. [ABSTRACT FROM AUTHOR]

The alternating copolymers containing tetraphenylethenes bonded to pseudo-para or pseudo-meta [2.2]paracyclophanes were synthesized by palladium catalyzed Suzuki-Miyaura cross-coupling reaction. Relatively high molecular weights of polymers were obtained by the reaction of their corresponding comonomers using Pd(OAc) 2 as a catalyst with S-Phos as a ligand and K 3 PO 4 as a base under a high base to monomer ratio. The maximum emission intensity of polymer in THF increases gradually as the addition of water fraction increases. The polymers exhibited aggregation-induced emission in aggregated state. In particular, the photoluminescence quantum yield of those tetraphenylethenes bonded to pseudo-meta [2.2]paracyclophanes is up to 0.334 when the water fraction reaches to 90%. The polymers used in the detection of 2,6-dinitrotoluene are more sensitive than that of small molecule containing the same conjugated segment of the polymers. They are promising candidates for potential uses in the optoelectronic applications. [ABSTRACT FROM AUTHOR]

ABSTRACT: In this study, polyvinyl chloride (PVC) has been modified through click grafting of chitosan onto its surface. This goal has been achieved using three consecutive steps involving amination, activation, and grafting. Both the amination and chitosan grafting steps were confirmed based on the determination of nitrogen content. The chemical structure of the modified PVC membranes was confirmed by FTIR spectroscopy and thermal analysis, and the morphological changes were monitored by scanning electron microscopy. In addition, the induced physicochemical characteristics were investigated by analyzing the water uptake, mechanical properties, surface roughness, and contact angle. Finally, an evaluation of blood compatibility and protein adsorption characteristics for the chitosan‐g‐PVC membranes is presented. [ABSTRACT FROM AUTHOR]

In the present study, systematic rheometric measurements are carried out to explore quasi-sinusoidal responses in the nonlinear regime of carbon black-filled monodispersed polyisoprene melts with molecular weights ranging from 3 to 390 kg/mol. Experimental results show that these quasi-sinusoidal responses emerge from a sharp transition as the molecular weight of the matrix, Mn, approaches and passes through a characteristic molecular weight Mc*. Below Mc*, the system typically shows the classic nonlinearity, where storage modulus G' decreases as strain amplitude γ0 increases and the resulting stress waveforms are distorted from sinusoidal waves. Above Mc*, the system displays anomalous nonlinearity, where the stress responses at any given strain remain surprisingly sinusoidal regardless the drop of modulus G'. In this manner, the system actually exhibits characteristic linear-nonlinear dichotomy in the rheological responses in the nonlinear regime. The critical point Mc* is found to be a few times of the entanglement molecular weight Me. Here, we introduce the linear-nonlinear-dichotomy transformation diagram for the particle-filled polymer system under oscillatory shears, delineating the boundaries between states of linear response, nonlinear response, and linear-nonlinear dichotomy response. [ABSTRACT FROM AUTHOR]

Controlling the backbone architecture of poly(lactic- co -glycolic acid)s (PLGAs) is demonstrated to have a strong influence on the production and release of acidic degradation by-products in microparticle matrices. Previous efforts for controlling the internal and external accumulation of acidity for PLGA microparticles have focused on the addition of excipients including neutralization and anti-inflammatory agents. In this report, we utilize a sequence-control strategy to tailor the microstructure of PLGA. The internal acidic microclimate distributions within sequence-defined and random PLGA microparticles were monitored in vitro using a non-invasive ratiometric two-photon microscopy (TPM) methodology. Sequence-defined PLGAs were found to have minimal changes in pH distribution and lower amounts of percolating acidic by-products. A parallel scanning electron microscopy study further linked external morphological events to internal degradation-induced structural changes. The properties of the sequenced and random copolymers characterized in vitro translated to differences in in vivo behavior. The sequence alternating copolymer, poly LG, had lower granulomatous foreign-body reactions compared to random racemic PLGA with a 50:50 ratio of lactic to glycolic acid. Statement of Significance This paper demonstrates that changing the monomer sequence in poly(lactic- co -glycolic acid)s (PLGAs) leads to dramatic differences in the rate of degradation and the internal acidic microclimate of microparticles degrading in vitro . We note that the acidic microclimates within these particles were imaged for the first time with two-photon microscopy, which gives an extremely clear and detailed picture of the degradation process. Importantly, we also document that the observed sequence-controlled in vitro processes translate into differences in the in vivo behavior of polymers which have the same L to G composition but differing microstructures. These data, placed in the context of our prior studies on swelling, erosion, and MW loss ( Biomaterials 2017 , 117 , 66 and other references cited within the manuscript), provide significant insight not only about sequence effects in PLGAs but into the underlying mechanisms of PLGA degradation in general. [ABSTRACT FROM AUTHOR]

Proton exchange membranes (PEMs) with well-defined microphase separation hold great promise for satisfying the demands of operation under high temperature and low humidity. Atom transfer radical polymerization (ATRP), as one of the most popular methods of controllable polymerization, has already been one of the most convenient tools for the synthesis of copolymers with well-defined microphase separated structures. This article tersely and concisely reviews the recent development of the PEMs prepared by ATRP for proton exchange membrane fuel cells. According to the different functional monomers in the polymerization, three kinds of membranes are systematically discussed in this feature article. The first membrane is made of copolymer grafted styrene by ATRP followed by post-sulfonation; the second membrane is prepared by directly grafting a sulfonated monomer to polymer using single-step ATRP; and the membranes grafted other types of monomers are divided into the third membranes. For each category of membrane, structures, properties, and their relationships are conducted targeted analysis. Finally, the perspectives of future trends on PEMs prepared via ATRP are presented. [ABSTRACT FROM AUTHOR]

In this paper, the recovered waste packaging ethylene-vinyl acetate copolymer (EVA) and crumb rubber (CR) were used as polymer modifying agents to prepare EVA/CR modified asphalt, and the EVA/CR modified asphalt’s dynamic stability were studied. After characterized and analyzed with conventional physical performance test, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), it can be found that the macro and micro properties of modified asphalt in the process of modification modified asphalt evolved from an unstable state to a dynamic stable state and until to a completely final stable state after removed the shear force. The polymer particles gradually dispersed evenly in the modified asphalt and a cross-linked polymer network structure was formed during the shearing process, which were clearly showed through the fluorescence microscopy images. Finally, the interaction between the polymer modifying agents and base asphalt and its impact to the properties of the system were also analyzed combining macro, micro properties of modified asphalt and the morphology changes of modifier and asphaltenes. In addition, stabilization mechanism of EVA/CR modified asphalt was revealed through the former analysis. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry measurement via fast-scan chip-calorimeter Flash DSC1 has been widely applied to investigate the crystallization kinetics of homopolymer and random copolymers. We expanded the measurement to the crystallization kinetics of isotactic polypropylene (iPP) blending with 29.3 wt% ethylene-co-propylene rubber (EPR) that contains 39.5 wt% ethylene monomers (toughening iPP). The temperature dependence of half-crystallization times of the blend show three regions of deviations from the parallel results of pure iPP, reflecting the effect of interplay between phase separation and crystallization. We attributed faster crystallization in the high-temperature region to crystal nucleation accelerated by the interfaces of two incompatible components, attributed slower crystallization in the middle-temperature region to crystal nucleation retarded by the crystallization of ethylene sequences in the minor EPR component, and attributed faster crystallization in the low-temperature region to crystal nucleation accelerated by the crystallization of propylene sequences in the minor EPR component. The suppression of crystallization on fast cooling as well as the variation of Avrami indexes support the scenario of crystallization competition in the middle temperature region. [ABSTRACT FROM AUTHOR]

In this work, poly(butylene succinate) (PBS), which is a well-established aliphatic polyester with excellent mechanical and thermal properties, was copolymerized with 2,5-furan dicarboxylic acid (FCDA) by melt polycondensation, for the formation of a poly(butylene succinate- co -furanoate) (PBSF) copolymer. The structural characteristics of the copolymer (PBSF) and both homopolymers (PBS, poly(butylene furanoate) − PBF) were studied by both wide angle X-ray diffraction (WAXD), while polarized light optical microscopy (PLOM) was utilized for the study of the spherulites grown at different temperatures. Differential scanning calorimetry (DSC) was used extensively for the evaluation of the thermal characteristics of the copolymer. The melting temperature and the glass transition of PBSF were observed at 106 °C and −29 °C respectively, while a depression of the melting point was also observed, compared to the homopolymers. The crystallization kinetics of the copolymer under isothermal and dynamic conditions were also studied using the Lauritzen–Hoffman and Avrami models. [ABSTRACT FROM AUTHOR]

Amphiphilic random copolyacrylamides bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic dodecyl pendants induce precision self-assembly to produce quite small uniform and/or necklace micelles (≈10 nm) in water. The size, structure, and thermoresponsive properties of the micelles are controlled by the primary structure (composition and chain length) of the copolymers. For this, random copolymers with different composition, chain length, and molecular weight distribution are synthesized by iron-catalyzed living or free radical copolymerization of PEG acrylamide and dodecyl acrylamide (DAAm). The copolymers with controlled molecular weight (degree of polymerization: ≈40) intermolecularly self-assemble and/or self-fold to form uniform (multichain or unimer) micelles in water; the size increases with increasing hydrophobic DAAm content (19-57 mol%: Mw = 43 900-191 000). In contrast, random copolymers with relatively small DAAm content (<35 mol%) and broad molecular weight distribution provide both uniform and necklace micelles in water. [ABSTRACT FROM AUTHOR]

ABSTRACT Hexadecyldimethylpropylmethacrylamide ammonium bromide was well prepared, allowed to copolymerize with other functional monomers to develop a hydrophobic associated polymer (PIADH) as a wide temperature range cement retarder. The synthetic copolymer was testified by Fourier transform infrared spectroscopy, 1H-nuclear magnetic resonance, thermo gravimetric analysis, and differential scanning calorimetry. Its temperature induced adaptability was verified via fluorescence probe and NaOH titration techniques, indicating that the retarding groups were increasing at elevated temperature. The applied performance of PIADH modified cement slurries was also evaluated. The results manifested that PIADH not only had excellent retarding property, but also was insensitive to its concentration and temperature variations. Meanwhile, it exhibited less impact on the compressive strength of set cement in large temperature difference. Besides, the inclusion of PIADH improved the microstructure of hardened cement, which was conducive to its mechanical property. The effect of PIADH on cement hydration was also investigated by the isothermal heat flow calorimetry and X-ray diffraction, showing that the retardation of PIADH was achieved through prolonging the induction period and inhibiting the nucleation of portlandite and ettringite crystals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45242. [ABSTRACT FROM AUTHOR]

Due to the spatial alignment of the nitrile groups and their involvement in the cyclization reactions during thermal oxidative stabilization (TOS) procedures, stereoregularity of polyacrylonitrile (PAN) precursors is one of the most important structural parameters to afford carbon materials. To elucidate this, PAN and poly(acrylonitrile- co -itaconic acid) with higher degree of isotacticity were prepared through template-assisted free-radical polymerization in the presence of MgCl 2 . Fourier-transform infrared spectroscopy was employed to quantitatively track the structural evolutions of the PAN (co)polymer precursors during their TOS procedures. The improved TOS efficiencies of the precursors were evidenced by high extents of cyclization, high concentrations of cyclized rings and enhanced oxygen uptakes of the isotactic PAN (co)polymers during the TOS procedures. The isotactic PAN (co)polymer precursors also exhibited relatively large heat evolutions with broad exothermic curves in differential scanning calorimetry observations, further suggesting efficient TOS procedures with safer processing conditions. The efficient TOS procedures of the isotactic PAN (co)polymer precursors resulted in carbon materials with high degrees of crystallinity and high amounts of sp 2 clusters, affording much improved electrical conductivities. This study provided knowledge on the structural characteristics of the precursors for carbon materials with pre-designed properties, which is critical for their success in high-end applications. [ABSTRACT FROM AUTHOR]

Of pyrolysis products formed from of poly(ethylene- co -vinyl acetate) (EVA), acetic acid is the most abundant species. When EVA was pyrolyzed without pre-pyrolysis step, broad acetic acid peak covered some pyrolysis product peaks in the chromatogram. Deacetylation step was introduced to remove acetic acid, and the optimal deacetylation condition was pre-pyrolysis at 400 °C for 10 min. Pyrolysis products formed from the deacetylated EVA were separated using gas chromatograph/mass spectrometer (GC/MS) equipped with PLOT column. Major pyrolysis products of the deacetylated EVA were n -alkanes, 1-alkenes, α,ω-alkadienes, and ring compounds. The n -alkanes, 1-alkenes, and α,ω-alkadienes are mainly generated from the ethylene homosequence, while the ring compounds are formed from the ethylene-vinyl acetate (VA) heterosequences. 1,3-Butadiene is formed from the one C C double bond sequence, while 4-vinlycyclohexene is formed from the ethylene-VA alternating sequence. [ABSTRACT FROM AUTHOR]

ABSTRACT To observe the effect of ENGAGE (a poly-olefin elastomer) on compatibilization of industrially important incompatible blend, high-density polyethylene (HDPE)/ethylene-propylene diene elastomer (EPDM), 15 wt % ENGAGE is incorporated into the system and the latter is found satisfactorily efficient as compatibilizer for the above system. To improve some industrially pertinent properties another strategies are also followed in addition, incorporation of magnesium hydroxide [Mg(OH)2] and electron beam (EB) crosslinking into the system. The gel content was found to increase with radiation dose, EPDM content and Mg(OH)2 dispersion. ENGAGE interestingly increases the gel content that is, promotes crosslinking. It is unique that filler dispersion and crosslinked network formation maintain the compatibility of the ternary system, which is confirmed by X-ray diffraction, differential scanning calorimetry, mechanical properties, and scanning electron microscope. The compatibilization, Mg(OH)2 dispersion, and EB crosslinking improve the mechanical, thermo mechanical, flame retardant properties, and phase morphology considerably. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44922. [ABSTRACT FROM AUTHOR]

DNA sequences capable of forming triplexes induce DNA double-strand breaks that have attracted attention in genome editing technologies (e.g., CRISPR/Cas9 system, TALEN, and ZFN). Therefore, novel functional tools that stabilize triplex DNA structures must be further investigated to spark renewed interest. In this study, we investigated the unique character of cationic comb-type copolymers for the selective stabilization of triplex DNA. The melting temperature (Tm) of triplex DNA increased from 24.5 to 73.0 °C (ΔTm = 48.5 °C) by the addition of poly(allylamine)-graft-dextran (PAA-g-Dex) under physiological conditions (at pH 7.0), while PAA-g-Dex did not stabilize but rather destabilized the DNA duplex. On the other hand, poly(l-lysine)-graft-dextran (PLL-g-Dex) stabilized both the duplex and triplex structures at pH 7.0. Thermodynamic parameters evaluated by isothermal titration calorimetry (ITC) revealed that the binding constant (Ka) for the intermolecular triplex formation in the presence of PAA-g-Dex was 1.1 × 109 M–1 at 25 °C which is more than 10 times larger than that in the presence of PLL-g-Dex (8.6 × 107 M–1). Stabilizing activity and selectivity of cationic copolymers toward DNA assemblies were successfully controlled by selecting appropriate backbone structures of the copolymer. Various functional molecules that stabilize DNA duplexes have been developed and used in biological research. However, there are few cationic polymers that stabilize triplex DNA selectively. This study indicates that PAA-g-Dex has great potential to regulate the biological activities of triplex DNA. [ABSTRACT FROM AUTHOR]