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Dislocations are essentially lines of point defects which can act as recombination centers in semiconductor devices. These point defects do not behave as isolated defects. Their spatial proximity enables them to hybridize into a one-dimensional band, and the distribution of resulting defect-band states is determined by both the position of the band and its dispersion. In the case of glissile 90 partial dislocations in III-V semiconductors, the dislocation core can adopt a variety of different reconstructions. Each of these reconstructions has a different arrangement of point defects, which affects the hybridization into defect bands and their associated dispersion. Here, we illustrate these principles by performing first-principles calculations for InAs and find that some defect levels for InAs dislocations lie outside of the band gap where they cannot act as recombination centers. To provide some insight into the electronic structure of dislocations in ternary alloys, some examples relevant to InGaAs and GaAsP are included. [ABSTRACT FROM AUTHOR]

Step-growth alternating interfacial polymerization between two miscible or immiscible monomer melts is investigated theoretically and by dissipative particle dynamics simulations. In both cases the kinetics for an initially bilayer system passes from the reaction to diffusion control. The polymer composed of immiscible monomers precipitates at the interface forming a film of nearly uniform density. It is demonstrated that the reaction proceeds in a narrow zone, which expands much slower than the whole film, so that newly formed polymer is extruded from the reaction zone. This concept of "reactive extrusion" is used to analytically predict the degree of polymerization and distribution of all components (monomers, polymer, and end groups) within the film in close agreement with the simulations. Increasing the comonomer incompatibility leads to thinner and more uniform films with the higher average degree of polymerization. The final product is considerably more polydisperse than expected for the homogeneous step-growth polymerization. The results extend the previous theoretical reports on interfacial polymerization and provide new insights into the internal film structure and polymer characteristics, which are important for membrane preparation, microencapsulation, and 3D printing technologies. A systematic way of mapping the simulation data onto laboratory scales is discussed. [ABSTRACT FROM AUTHOR]

In this paper, we present a concentrator system based on a stack of fluorescent concentrators (FCs) and a bifacial solar cell. Coupling bifacial solar cells to a stack of FCs increases the performance of the system and preserves its efficiency when scaled. We used an approach to optimize a fluorescent solar concentrator system design based on a stack of multiple fluorescent concentrators (FC). Seven individual fluorescent collectors (20mm20mm2mm) were realized by in-situ polymerization and optically characterized in regard to their ability to guide light to the edges. Then, an optimization procedure based on the experimental data of the individual FCs was carried out to determine the stack configuration that maximizes the total number of photons leaving edges. Finally, two fluorescent concentrator systems were realized by attaching bifacial silicon solar cells to the optimized FC stacks: a conventional system, where FC were attached to one side of the solar cell as a reference, and the proposed bifacial configuration. It was found that for the same overall FC area, the bifacial configuration increases the short-circuit current by a factor of 2.2, which is also in agreement with theoretical considerations. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the effects of light exposure times on water sorption, solubility, and polymer cross-linking density of simplified etch-and-rinse adhesives. Materials and Methods: Four commercial adhesives (XP Bond, Adper Single Bond 2, Tetric N-Bond, and Ambar) were selected, and resin disks 5 mm in diameter and 1.0 mm thick were prepared and light cured for 20, 40, or 80 s using an LED light-curing unit at 1200 mW/cm². Water sorption and solubility were evaluated over a 28-day period. For polymer cross-linking density, additional specimens were prepared and their Knoop hardness measured before and after immersion in 100% ethanol. The data from each test were evaluated using a two-way ANOVA and Tukey's test (α = 0.05). Results: The XP Bond adhesive showed higher water sorption (similar to Adper Single Bond 2) and solubility (p < 0.05) than did the other materials. Prolonged exposure times did not reduce the water sorption but did reduce the solubility of all tested materials (p < 0.05). For Ambar, the increase in the exposure time resulted in a significantly lower percent reduction in hardness. Conclusion: Water sorption, solubility, and cross-linking density of the materials selected in this study seem to be mainly influenced by the adhesive composition. Prolonged light exposure times reduced the solubility of the materials. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the mechanical and physical properties of experimental HEMA-containing and HEMA-free resin adhesives. Materials and Methods: Experimental HEMA-free adhesives containing alternative dimethacrylates (bis-EMA 10 [B10], bis-EMA 30 [B30], PEG 400 [P400], PEG 1000 [P1000], PEG 400 UDMA [UP400]) were formulated and compared with a HEMA-containing adhesive (control). The adhesives were characterized by rheological analysis, polymerization kinetics (PK), water sorption (WS), and solubility (SL) tests. Flexural strength (FS) and flexural modulus (E) tests were performed under dry or wet conditions (distilled water or 70% ethanol solution). One-way and two-way ANOVA as well as Tukey's test were used to evaluate differences between groups (p < 0.05). Results: The control group showed the lowest viscosity and was the only one with a degree of conversion lower than 50%. The control and the P1000 adhesive showed the statistically significantly highest WS (p < 0.05). The control and the UP400 adhesive showed the highest FS and E, and the dry-stored specimens showed more improved mechanical strength than did the wet-stored specimens (p < 0.05). Conclusion: The physicomechanical properties of some of the HEMA-free adhesives were substantially improved when compared with those of the control, indicating that they could be potential monomers for the development of HEMA-free adhesive systems. [ABSTRACT FROM AUTHOR]

Impulse laser heating combined with a quick sample cooling in a diamond anvil cell provides unique conditions for the 3D polymerization reaction of C60. The reaction proceeds under the 8-10 GPa pressure and 2700K temperature in the case of heating-cooling cycle time around 0.1 μs. Such a short heating time permits to increase the maximal temperature of the fullerite sample by 1700K on conditions that C60 are still surviving. As a result, the pressure of the phase transition to 3D polymerized fullerite phase with 519 GPa bulk modulus was essentially decreased. Furthermore, the transition has proceeded at quasi-hydrostatic conditions without activation by applying a plastic deformation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of mechanical cycling and cementation strategies on the push-out bond strength between fiber posts and root dentin and the polymerization stresses produced using three resin cements. Materials and Methods: Eighty bovine mandibular teeth were sectioned to a length of 16 mm, prepared to 12 mm, and embedded in self-curing acrylic resin. The specimens were then distributed into 8 groups (n = 10): Gr1 - Scotchbond Multi Purpose + RelyX ARC; Gr2 - Scotchbond Multi Purpose + RelyX ARC + mechanical cycling; Gr3 - AdheSE + Multilink Automix; Gr4 - AdheSE + Multilink Automix + mechanical cycling; Gr5 - phosphoric acid + RelyX U100 (self-adhesive cement); Gr6 - phosphoric acid+ RelyX U100 + mechanical cycling; Gr7 - RelyX U100; Gr8 - RelyX U100 + mechanical cycling. The values obtained from the push-out bond strength test were submitted to two-way ANOVA and Tukey's test (p = 0.05), while the values obtained from the polymerization stress test were subjected to one-way ANOVA and Tukey's test ( = 0.05). Results: Mechanical cycling did not affect the bond strength values (p = 0.236), while cementation strategies affected the push-out bond strength (p < 0.001). Luting with RelyX U100 and Scotch Bond Multi Purpose + RelyX ARC yielded higher push-out bond strength values. The polymerization stress results were affected by the factor "cement" (p = 0.0104): the self-adhesive cement RelyX U100 exhibited the lowest values, RelyX ARC resulted in the highest values, while Multilink Automix presented values statistically similar to the other two cements. Conclusion: The self-adhesive cement appears to be a good alternative for luting fiber posts due to the high push-out bond strengths and lower polymerization stress values. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this literature review was to investigate the results from in vitro laboratory studies on the influence of temperature and relative humidity present before polymerization on enamel and dentin bonding systems. Materials and Methods: A systematic search was carried out including articles published in English, in peer-reviewed journals, and indexed in MEDLINE/PubMed database. The search was carried out using the terms: relative AND humidity AND dental. In vitro studies were retrieved and divided into laboratory simulation studies and studies on physical properties. Laboratory simulation studies were addressed by subtopic: resin-enamel bond strength, resin-dentin bond strength, and dentin-enamel microleakage. Studies on physical properties tested the influence of humidity and temperature through polymerization contraction, flexural strength, and dentin wettability. Results: Laboratory simulation studies demonstrated a strong influence of humidity and temperature on dentin and enamel bond strength and microleakage with dental adhesives systems. The studies on physical properties failed to demonstrate any influence of humidity on the adhesion performance, except for wettability measurement. Conclusion: The clinical relevance of these in vitro results remains to be demonstrated. A review of in vivo clinical studies will complete the literature data presented here. [ABSTRACT FROM AUTHOR]

Here, we report the synthesis of polyaniline-zirconium nanocomposite by chemical oxidative polymerization of aniline. Structural, thermal, and morphological properties of the samples are characterized by XRD, FTIR, TGA, SEM, and UV-Vis spectroscopy. Crystalline behavior of the nanocomposite has been obtained due to the presence of zirconium nanoparticles in polyaniline. FTIR analysis reveals the formation of polyaniline and changes to the structure of polyaniline due to the presence of zirconium nanoparticles. Granular morphology of the nanocomposite has been obtained from SEM micrographs and its conductivity has been increased due to the incorporation of zirconium nanoparticles. Temperature dependence of the resistivity has been fitted with ln [ρ(T)] ∝ T-1/4 which indicates three dimensional variable range hopping transport mechanism. ac conductivity follows the correlated barrier hopping transport mechanism. Some optical parameters like bandgap (Eg), peak transition energy (E0), and peak broadening parameter (C) are evaluated from real and imaginary dielectric functions. The value of the bandgap indicates the formation of a polaron lattice structure of the protonated emeraldine form of polyaniline. [ABSTRACT FROM AUTHOR]

Objective: Early bond strengths produced by dentin bonding systems should be sufficient to resist the polymerization shrinkage of resin composite. This study compared the 10-minute and 24-hour shear bond strengths of six dentin bonding systems: One-Step (OS), PermaQuik (PO), Prime S Bond 2.1 (PB), Scotchbond Multi-Purpose (SBMP), Single Bond (SB), and Tenure Quik with Fluoride (TQ). Method and materials: Each bonding system was used to bond composite to visibly moist dentin at 34°C ± 2°C. The specimens were debonded at 37°C ± 1°C 10 minutes alter the start of light curing of the bonding system, and the results were compared with the 24-hour bond strengths. The mode of failure was recorded. Results: The 10-minute mean shear bond strengths were: OS, 16.4; PQ, 14.3; SB, 14.0; PB, 12.7;TQ, 10.7; and SBMP, 9.3 MPa. The 24-hour mean shear bond strengths were OS, 23.3; PB, 20.8; SB, 20.3; PQ, 19.4; TQ, 11.2; and SBMP, 10.0 MPa. The 10-minute mean shear bond strengths of OS, PQ, PB, and SB bonding systems were significantly less than the 24-hour values. More dentinal fractures and mixed failures were observed with OS, PQ, and PB. Systems with higher bond strengths had more resin penetration into the lateral dentinal branches. Conclusion: The 10-minute mean shear bond strengths were all less than 17 MPa, and the 10-minute bond strengths were less than the 24-hour values. (Quintessence Int 1999;30:122-134) [ABSTRACT FROM AUTHOR]

Abstract: There is a strong imperative to synthesize polymers with highly controlled structures and narrow property ranges. Silicone polymers do not lend themselves to this paradigm because acids or bases lead to siloxane equilibration and loss of structure. By contrast, elegant levels of control are possible when using the Piers–Rubinsztajn reaction and analogues, in which the hydrophobic, strong Lewis acid B(C6F5)3 activates SiH groups, permitting the synthesis of precise siloxanes under mild conditions in high yield; siloxane decomposition processes are slow under these conditions. A broad range of oxygen nucleophiles including alkoxysilanes, silanols, phenols, and aryl alkyl ethers participate in the reaction to create elastomers, foams and green composites, for example, derived from lignin. In addition, the process permits the synthesis of monofunctional dendrons that can be assembled into larger entities including highly branched silicones and dendrimers either using the Piers–Rubinsztajn process alone, or in combination with hydrosilylation or other orthogonal reactions. [ABSTRACT FROM AUTHOR]

A novel electroactive macromonomer based on poly( l -lactic acid) (PLLA) with (3,4-ethylenedioxythiophene) (EDOT) functional end groups, was prepared by a traditional approach of organometallic polymerization with stannous octanoate [Sn(oct 2 )] and enzymatic polymerization using immobilized Candida antarctica Lipase B (CAL-B) and Amano lipase Pseudomonas cepacia (PS-IM), as catalysts. In the synthetic strategy, (2,3-dihydrothieno[3,4-b] dioxin-2-yl)methanol (EDOT-OH) was used to initiate the ring opening polymerization of lactide to yield PLLA with EDOT end group. All macromonomers (EDOT-PLLA) were characterized by 1 H and 13 C RMN, MALDI-TOF, GPC and EDX. Moreover, ICP-OES analysis showed the presence of Sn traces in the material synthesized by the traditional approach, but that pathway led to macromonomers with higher molecular weight while the enzymatic route led to completely metal-free macromonomers with medium and lower molecular weights. Also, electrochemical and chemical polymerization of EDOT-PLLA were tested showing that it is possible to prepare degradable conducting polymers based on poly(3,4-ethylenedioxythiphene) (PEDOT). The biocatalytic synthesis is a very promising and environmental friendly pathway for the preparation of biodegradable materials for short time applications. [ABSTRACT FROM AUTHOR]

Pd-initiated polymerization of fluorine (F)-containing alkyl and phenyl diazoacetates is described. Polymerization of 2,2,2-trifluoroethyl diazoacetate [Et(CF3)DA] with π-allylPdCl afforded a C-C main chain polymer bearing a 2,2,2-trifluoroethoxycarbonyl group on each main chain carbon atom. The polymer showed upper critical solution temperature (UCST)-type phase separation in multiple common organic solvents with differing polarities. Although homopolymerization of 3,3,4,4,5,5,6,6,6-nonafluorohexyl diazoacetate [Hex(C4F9)DA] with a higher fluorine content yielded an insoluble product, copolymerization of Hex(C4F9)DA with non-fluorinated ethyl diazoacetate (EDA) proceeded homogeneously to give a soluble F-containing copolymer. Polymerization of a series of F-containing phenyl diazoacetates was also conducted with the same initiator, giving poly[(F-containing aryloxycarbonyl)methylene]s, which showed significant solubility differences depending on the substitution pattern of F atoms on the phenyl ring. Efficient postpolymerization modification of poly[(F-containing aryloxycarbonyl)methylene]s was achieved with a primary amine, affording a polymer with both a five-membered cyclic imide structure and an N-alkylcarbamoyl group in its side chains. [ABSTRACT FROM AUTHOR]

Since its introduction in 2014, the sulfur(VI) fluoride exchange (SuFEx) reaction has emerged as a promising new reaction in the field of polymer chemistry, in both polymerization of diverse polymer backbones and postpolymerization modification (PPM). Previously, we successfully reported the use of SuFEx chemistry as a method for surface derivatization through the PPM of sulfonyl fluoride containing polymer brushes. However, with the diversity of conditions, substrate scope, and catalyst selection afforded by this reaction, it is advantageous to expand the use of SuFEx for PPM on polymer brushes to discern the advantages and limitations of this reaction in surface conjugation. In this work, we used three different polymer brush systems--alkyl sulfonyl fluorides, aromatic sulfonyl fluorides, and aromatic fluorosulfonates--and each was reacted with three different silyl ether derivatives (aryl, alkyl, and benzyl). Each of these reactions was subjected to different catalysts, and herein, we present rates, conditions, and side products for PPM of polymer brushes using SuFEx chemistry. In addition, we explored the use of TBDMS brushes and their reaction with fluorosulfonate derivatives, where surprisingly no surface reaction occurs. With these studies, we are able to better understand the rates and limitations of this click reaction in the context of surface derivatization. [ABSTRACT FROM AUTHOR]

Lipoteichoic acid (LTA) is an anionic surface polymer that is essential for normal growth of Staphylococcus aureus, making the LTA polymerase, LTA synthase (LtaS), a proposed drug target for combating Staphylococcal infections. LtaS is a polytopic membrane protein with five membrane-spanning helices and an extracellular domain, and it uses phosphatidylglycerol to assemble a glycerol phosphate chain on a glycosylated diacylglycerol membrane anchor. We report here the first reconstitution of LtaS polymerization activity and show that the azo dye Congo red inhibits this enzyme both in vitro and in cells. Related azo dyes and the previously reported LtaS inhibitor 1771 have weak or no in vitro inhibitory activity. Synthetic lethality with mutant strains known to be nonviable in the absence of LTA confirms selective inhibition by Congo red. As the only validated LtaS inhibitor, Congo red can serve as a probe to understand how inhibiting lipoteichoic acid biosynthesis affects cell physiology and may also guide the discovery of more potent inhibitors for use in treating S. aureus infections. [ABSTRACT FROM AUTHOR]

The mechanism of the recently reported photocontrolled cationic polymerization of vinyl ethers was investigated using a variety of catalysts and chain-transfer agents (CTAs) as well as diverse spectroscopic and electrochemical analytical techniques. Our study revealed a complex activation step characterized by one-electron oxidation of the CTA This oxidation is followed by mesolytic cleavage of the resulting radical cation species, which leads to the generation of a reactive cation -- this species initiates the polymerization of the vinyl ether monomer -- and a dithiocarbamate radical that is likely in equilibrium with the corresponding thiuram disulfide dimer. Reversible addition -- fragmentation type degenerative chain transfer contributes to the narrow dispersities and control over chain growth observed under these conditions. Finally, the deactivation step is contingent upon the oxidation of the reduced photocatalyst by the dithiocarbamate radical concomitant with the production of a dithiocarbamate anion that caps the polymer chain end. The fine-tuning of the electronic properties and redox potentials of the photocatalyst in both the excited and the ground states is necessary to obtain a photocontrolled system rather than simply a photoinitiated system. The elucidation of the elementary steps of this process will aid the design of new catalytic systems and their real-world applications. [ABSTRACT FROM AUTHOR]

An attempt has been made to prepare electrically conductive fibres by coating common textile fibres such as cotton, wool, silk, polyester, nylon, acrylic, and polypropylene with polypyrrole by in-situ chemical polymerization of pyrrole using FeCl 3 as oxidant and p-toluene sulphonic acid as dopant in aqueous medium. Effects of the pyrrole, oxidant and dopant concentrations and substrate textile fibres on reaction kinetics of the in-situ chemical polymerization are investigated. A comparative analysis is done to find out the most suitable textile fibre as substrate for in-situ polymerization of pyrrole. Highest polypyrrole add-on per unit surface area have been observed in case of wool fibre (12.094 g − 2 ) followed by cotton (5.125 g − 2 ) and silk (4.621 g − 2 ). Whereas, the synthetic fibres show comparatively lower polypyrrole add-on than that of the natural fibres. This difference in add-on may primarily be attributed to interaction between these fibres with polypyrrole, which lead to improved fixation of polypyrrole on these fibre surfaces. The chemical interaction is investigated by FTIR and DSC analysis of the control and the polypyrrole coated fibres. Significant chemical interaction has been found in case of wool, silk, cotton and polyester fibres in terms of formation of hydrogen bonds. [ABSTRACT FROM AUTHOR]

In this contribution a convenient synthetic method to obtain tetraacylgermanes Ge[C(O)R]4 (R=mesityl ( 1 a), phenyl ( 1 b)), a previously unknown class of highly efficient Ge-based photoinitiators, is described. Tetraacylgermanes are easily accessible via a one-pot synthetic protocol in >85 % yield, as confirmed by NMR spectroscopy, mass spectrometry, and X-ray crystallography. The efficiency of 1 a, b as photoinitiators is demonstrated in photobleaching (UV/Vis), time-resolved EPR (CIDEP), and NMR/CIDNP investigations as well as by photo-DSC studies. Remarkably, the tetraacylgermanes exceed the performance of currently known long-wavelength visible-light photoinitiators for free-radical polymerization [ABSTRACT FROM AUTHOR]

Dispersion polymerization is a well-established method of producing polymer particles that are easily handled and processed. With careful choice of reaction conditions this technique can yield well defined, spherical particles for a wide range of applications. The use of supercritical carbon dioxide (scCO2) as a reaction medium offers a route to performing these syntheses without excessive use of volatile organic solvents and minimizes work-up and disposal steps. However a significant drawback has been the fact that up till now the control of particle size and morphology from CO2 have been limited. This study presents control of particle size and morphology over an unprecedented range for a single stabilizer in scCO2 by coordinating a few simple parameters to tailor the conditions toward different sizes. Further, this study introduces the novel approach in scCO2 of using delayed monomer addition which allows considerable reduction of the batch-to-batch variability as well as reduced agglomeration between particles. [ABSTRACT FROM AUTHOR]

The terpolymerization of CO, ethylene, and additional olefins varies the properties of polyketones depending on olefins. In this study, monomer candidates for the terpolymerization of polyketones were expanded to alkynes, in addition to olefins. Thermal properties of polyketones were modified by adding aromatic alkynes during Pd-catalyzed terpolymerization with CO and ethylene. The Tm values of terpolymers were reduced to 192-215°C. [ABSTRACT FROM AUTHOR]

ABSTRACT Hyperbranched poly(ether sulfone) (HPES), a suitable coating additive for improving the rheological properties of linear poly(ether sulfone) (LPES), was easily produced via polymerization of commercially available bisphenol S (A2 monomer, BPS) and synthesized 2,4′,6-trifluoro-phenylsulfone (BB′2 monomer, TF). During this reaction, fluoro- or phenolic-terminated HPES (F-HPES or OH-HPES) could be facilely obtained by controlling the feed mole ratios of the two monomers. The polymerization mode A2 + BB′2 was confirmed by analyzing the model compounds and the degree of branching (DB) was calculated systematically. In addition, the synthesized polymers' chemical structures were exhibited by FTIR, 1H NMR as well as 19F NMR spectroscopy. Notably, the addition of 1 wt % HPES reduced the melt viscosity and improved the high temperature liquidity of LPES because of its unique spherical shape. Furthermore, the addition of HPES did not have a negative impact on the performance of LPES, which was attributed to the good miscibility between HPES and LPES. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43892. [ABSTRACT FROM AUTHOR]

ABSTRACT The high polymerization temperature of acrylic bone cements used in hip replacement implantation may cause thermal necrosis of surrounding tissues. In order to reduce the polymerization temperature, acrylic bone cement has been modified with a biocompatible polymeric phase-change material (PCM) based on poly(ethylene glycol) (PEG) of different molecular weights and stabilized with potato starch. Structural and morphological studies were performed, and the thermal and mechanical properties were investigated. The incorporation of PEG-based PCM led to a decrease in the polymerization temperature of bone cement from 70 °C for unmodified cement to 58 °C for modified cement. Modified cement materials were stable in incubation tests, although acoustic analysis data revealed a decrease in propagation speed after incubation, which indicates formation of material defects (pores, cracks, voids, etc.) due to water activity. However, in the regeneration process, these defects can be filled by freshly grown bone tissue leading to better incorporation of bone cement replacements into tissue. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43898. [ABSTRACT FROM AUTHOR]

ABSTRACT Interface interactions of fiber-matrix play a crucial role in final performance of polymer composites. Herein, in situ polymerization of glycidyl methacrylate (GMA) on the ultrahigh molecular weight polyethylene (UHMWPE) fibers surface was proposed for improving the surface activity and adhesion property of UHMWPE fibers towards carbon nanofibers (CNF)-epoxy nanocomposites. Chemical treatment of UHMWPE fibers was characterized by FTIR, XPS analysis, SEM, and microdroplet tests, confirming that the grafting of poly (GMA) chains on the surface alongside a significant synergy in the interfacial properties. SEM evaluations also exhibited cohesive type of failure for the samples when both GMA-treated UHMWPE fiber and CNF were used to reinforce epoxy matrix. Compared with unmodified composite, a ∼319% increase in interfacial shear strength was observed for the samples reinforced with both 5 wt % GMA-grafted UHMWPE and 0.5 wt % of CNF. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43751. [ABSTRACT FROM AUTHOR]

ABSTRACT An alternative method to improve the compatibility between poly(lactic acid) (PLA) and cassava starch (CS) is proposed and investigated. Admicellar polymerization is used to modify the surface of CS with poly(methyl methacrylate) (PMMA) in order to make it more hydrophobic and hence more compatible with PLA. The increased hydrophobicity of PMMA modified cassava starch (MS) is validated by contact angle measurement. Results from iodine test, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) confirm the formation of PMMA film on MS surface. Mechanical properties of PLA-CS and PLA-MS blends are investigated to compare their compatibility. Noticeable improvements in blend tensile strength and elongation at break evidently show that MS is more hydrophobic as well as more compatible with PLA than CS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43755. [ABSTRACT FROM AUTHOR]

ABSTRACT The study provides detailed information on the differences in the structural, thermal and degradation properties of poly(ε-caprolactone) synthesized in two different ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [bmim][NTf2], regarding its further usage in the pharmaceutical field. The polymer structure confirms the presence of both linear polymer chains with end-functional hydroxyl groups allowing covalent coupling of the therapeutic agents, and cyclic macromolecules, both affecting the degree of crystallinity of polymer. The highest macrocyclic content (64%) after 7 days of polymerization at 80 °C was observed for [bmim][NTf2]. For [bmim][PF6], the macrocyclic content value was not dependent on the reaction time and remained at a similar level (10-14% at 80 °C). The results of degradation test revealed that hydrolytic degradation of ester bonds is more pronounced for PCLs synthesized in [bmim][NTf2], due to their lower degree of crystallinity compared with PCLs obtained in [bmim][PF6]. A high purity, low polydispersity index of the obtained polymers and high yield of the process (ca., 90%) indicate that ionic liquids seem to be promising solvents for the synthesis of biomedical polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43728. [ABSTRACT FROM AUTHOR]

Curcumin is a potential natural anticancer drug with low oral bioavailability because of poor water solubility. The aqueous solubility of curcumin is enhanced by means of modification with the carbohydrate units. Polymerization of the curcumin-containing monomer with carbohydrate-containing monomer gives the water-soluble glycopolymer bearing curcumin pendant residues. The obtained copolymers (P1andP2) having desirable water solubility were well-characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), UV–Vis absorption spectroscopy, and photoluminescence spectroscopy. The copolymerP2with a molar ratio of 1:6 (curcumin/carbohydrate) calculated from the proton NMR results exhibits a similar anticancer activity compared to original curcumin, which may serve as a potential chemotherapeutic agent in the field of anticancer medicine. The prepared glycopolymer (P2) bearing curcumin residues exhibit a similar anticancer activity to original curcumin. [ABSTRACT FROM PUBLISHER]

A series of cross-linkable bipolar host materials containing carbazole (donor, D) and 1,2,4-triazole (acceptor, A) were designed and synthesized. The host materials with styryl groups can be thermally cross-linked by curing at 172-190 °C without any polymerization initiator. Excellent solvent resistance was observed for all the host materials, which is beneficial for the preparation of subsequent functional layers by solution processes. The highest occupied molecular orbital energy levels of 5.55, 5.58 and 5.54 eV are estimated for these host materials, which indicates low injection barrier from the hole transport layer. A current efficiency of 15.3 cd A-1 and an external quantum efficiency of 4.6 % were achieved for solution-processed Ir(mppy)3-based OLEDs by using the cross-linkable host material. [ABSTRACT FROM AUTHOR]

The focus of this research is a special technique to investigate the polymerization of the water soluble monomer acrylic acid in a rheometer. The rheokinetics is an approach to measure the viscosity of reactive solutions during polymerization and consequently monitor the reaction kinetics. Results are presented on the initial stage of acrylic acid polymerization in water at different temperatures, 50, 60, and 70°C with mass fractions between 12.5% and 35% and two different initiator ratios, 0.8 and 1.2 mmol/mol. An empirical viscosity model to describe the shear viscosity over time is available. With reaction kinetics from literature and the viscosity model, a determination of the exponents [ABSTRACT FROM AUTHOR]

One-dimensional π-conjugated polymer chains with variable lengths have been synthesized successfully via thermal polymerization reaction on the Au(111) surface. Such polymer chains form parallel arrays along specific directions according to the initial assembly orientations of the close-packed Br-BTTN precursors. [ABSTRACT FROM AUTHOR]

To meet the growing demand for rapid heat dissipation in electronic devices to ensure their reliable performance with a high level of safety, many polymer composites with thermally conductive but electrically insulating 2D boron nitride nanosheets (BNNSs) are being developed. Here we present an efficient way to enhance the thermal conductivity (TC) of a polymer composite by means of "grafting-from" polymerization of a poly(caprolactone) (PCL) onto BNNSs. The BNNSs, which were exfoliated from bulk BN by means of ultra-sonication, were prepared by means of radi cal oxidation. These oxidized BNNSs (oxi-BNNSs) were employed as initiators for subsequent ring-opening polymerization of PCL, which successfully resulted in PCL chemically grafted onto BNNSs (PCL-g-BNNSs). The excellent dispersion of PCL-g-BNNSs in common solvents allowed us to readily fabricate a polymer composite that contained PCL-g-BNNSs embedded in a PCL matrix, and the composite showed TC values that were five and nine times greater in the out-ofplane and in-plane mode, respectively, than those of pristine PCL. [ABSTRACT FROM AUTHOR]

Vertical polyaniline (PANI) nanowire arrays on graphene-sheet-coated polyester cloth (RGO/PETC) were fabricated by the in situ chemical polymerization of aniline. The 3D conductive network that was formed by the graphene sheets greatly enhanced the conductivity of PANI/RGO/PETC and improved its mechanical stability. PANI nanowire arrays increased the active surface area of PANI, whilst the hierarchically porous structure of the PANI/RGO/PETC electrode facilitated the diffusion of the electrolyte ions. Electrochemical measurements showed that the composite electrode exhibited a maximum specific capacitance of 1293 F g-1 at a current density of 1 A g-1 Capacitance retention was greater than 95%, even after 3000 cycles, which indicated that the electrode material has excellent cycling stability. Moreover, the electrode structure endowed the PANI/RGO/PETC electrode with a stable electrochemical performance under mechanical bending and stretching. [ABSTRACT FROM AUTHOR]

ABSTRACT Polymerization-based signal amplification, a technique developed for use in rapid diagnostic tests, hinges on the ability to localize initiators as a function of interfacial binding events. We report here a new DNA detection method in which polymer growth in redox-polymerization is used as a means to amplify detection signals. The introduction of biotin-labeled chitosan (biotin-CS) with highly dense amino groups into the polymerization amplification as macromolecular reducing agent, beneficially simplifies amplification operation, as well as, provides a large amount of initiation points to improve the sensitivity of detection. DNA hybridization, SA and biotin binding reactions led to the attachment of CS on a solid surface where specific DNA sequences were located. With the addition of the mixture containing monomer AM, crosslinker PEGDA and oxidant CAN onto the CS location, the growth of polymer films was triggered to render the corresponding spots readily distinguishable to the naked eye. Direct visualization of 0.21 fmol target DNA molecules of interest was demonstrated. Non-small cell lung cancer p53 sequence was further selected as a proof-of-principle to detect DNA point mutation. The proposed method exhibited an efficient amplification performance for molecule detection, and paved a new way for visual diagnosis of biomolecules. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1929-1937 [ABSTRACT FROM AUTHOR]

ABSTRACT Two D-π-A-type 2,2,2-trifluoroacetophenone derivatives, namely, 4′-(4-( N, N-diphenyl)amino-phenyl)-phenyl-2,2,2-trifluoroacetophenone (PI-Ben) and 4′-(4-(7-( N, N-diphenylamino)-9,9-dimethyl- 9H-fluoren-2-yl)-phenyl-2,2,2-trifluoroacetophenone (PI-Flu), are developed as high-performance photoinitiators combined with an amine or an iodonium salt for both the free-radical polymerization of acrylates and the cationic polymerization of epoxides and vinyl ether upon exposure to near-UV and visible light-emitting diodes (LEDs; e.g., 365, 385, 405, and 450 nm). The photochemical mechanisms are investigated by UV-Vis spectra, molecular-orbital calculations, fluorescence, cyclic voltammetry, photolysis, and electron-spin-resonance spin-trapping techniques. Compared with 2,2,2-trifluoroacetophenone, both photoinitiators exhibit larger redshift of the absorption spectra and higher molar-extinction coefficients. PI-Ben and PI-Flu themselves can produce free radicals to initiate the polymerization of acrylate without any added hydrogen donor. These novel D-π-A type trifluoroacetophenone-based photoinitiating systems exhibit good efficiencies (acrylate conversion = 48%-66%; epoxide conversion = 85%-95%; LEDs at 365-450 nm exposure) even in low-concentration initiators (0.5%, w/w) and very low curing light intensities (1-2 mW cm−2). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1945-1954 [ABSTRACT FROM AUTHOR]

ABSTRACT Acrylonitrile (AN) was polymerized by initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP). The effect of the ligand, tris(2-pyridylmethyl)amine (TPMA) and N, N, N', N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), in the Cu-based catalyst, the amount of catalyst, several alkyl halide initiators, targeted degree of polymerization, and amount of azobisisobutyronitrile (AIBN) added were studied. It was determined that the best conditions utilized 50 ppm of CuBr2/TPMA as the catalyst and 2-bromopropionitrile (BPN) as the initiator. This combination resulted in 46% conversion in 10 h and polyacrylonitrile (PAN) with the narrowest molecular weight distribution ( Mw/ Mn = 1.11-1.21). Excellent control was maintained after lowering the catalyst loading to 10 ppm, with 56% conversion in 10 h, experimental molecular weight closely matching the theoretical value, and low dispersity ( Mw/ Mn < 1.30). Catalyst loadings as low as 1 ppm still provided well-controlled polymerizations of AN by ICAR ATRP, with 65% conversion in 10 h and PAN with relatively low dispersity ( Mw/ Mn = 1.41). High chain end functionality (CEF) was confirmed via 1H NMR analysis, for short PAN chains, and via clean chain extensions with n-butyl acrylate (BA). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1961-1968 [ABSTRACT FROM AUTHOR]

ABSTRACT The poly(methyl methacrylate) -b-poly(2-[[[[2-(perfluorohexyl)]-sulfonyl]-amino]ehthyl] methacrylate) (PMMA -b-PC6SMA) copolymers were successfully synthesized for the first time using activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) method. Under optimized reaction conditions, the degree of polymerization (DP) of resulting copolymers increased approximately linearly with monomer conversion. Structures of a well-defined block copolymer were determined by GPC, FT-IR, and 1H-NMR spectra. Results from AFM and contact angle measurements of polymer films revealed the presence of block segments derived from PC6SMA, as indicated by the obvious increase in hydrophobicity and oleophobicity. The relationship between surface composition and surface wetting ability was confirmed by XPS and AFM spectra. Compared with the random copolymer PMMA -co-PC6SMA, C6SMA dosages in the PMMA -b-PC6SMA copolymers were greatly decreased, which retained its hydrophobic and oleophobic properties. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2040-2049 [ABSTRACT FROM AUTHOR]

ABSTRACT Tetrakis(4-(1-bromoethyl)phenyl)silane is synthesized and utilized to initiate the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to generate bromo-terminated four-armed PMMA macroinitiators, which further initiate the ATRP of methylacryloyloxyl-2-hydroxypropyl perfluorooctanoate (FGOA) to create fluorinated star-shaped block copolymers PMMA- b-poly(FGOA)s with fluorine content ranging from 0 to 31.7 wt %. The polymerizations are well controlled with the polydispersity indices <1.30. The polymers readily dissolve in common organic solvents and show good film-formation. Compared with the nonfluorinated sample, the fluorinated films exhibit significantly increased water contact angles owing to the enrichment of fluorine on the surface. The enhanced hydrophobicity is advantageous for the optical stability when the devices work under a moist environment. Moreover, the films possess high thermo-optic coefficients, tunable refractive indices, and extremely low birefringence coefficients because of the presence of bulky and rigid tetraphenylsilane core and star-shaped topological structure, showing potential application in optical waveguide devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1969-1977 [ABSTRACT FROM AUTHOR]

ABSTRACT The radical polymerization of 1-vinylpyrrolidin-2-one (NVP) in poly(lactic- co-glycolic acid) (PLGA) 50:50 at 100 °C leads to amphiphilic PLGA- g-PVP copolymers. Their composition is determined by FT-IR spectroscopy. Thermogravimetric analyses agree with FT-IR determinations. Saponification of the PLGA- g-PVP polyester portion allows isolating the PVP side chains and measuring their molecular weight, from which the average chain transfer constant ( CT) of the PLGA units is estimated. The MALDI-TOF spectra of PVP reveal the presence at one chain end of residues of either glycolic acid- or lactic acid- or lactic/glycolic acid dimers, trimers and one tetramer, the other terminal being hydrogen. This unequivocally demonstrates that grafting occurred. Accordingly, the orthogonal solvent pair ethyl acetate-methanol, while separating the components of PLGA/PVP intimate mixtures, fails to separate pure PVP or PLGA from the reaction products. All PLGA- g-PVP and PLGA/PLGA- g-PVP blends, but not PLGA/PVP blends, give long-time stable dispersions in water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1919-1928 [ABSTRACT FROM AUTHOR]

ABSTRACT Redox-active anthraquinone based polymers are synthesized by the introduction of a polymerizable vinyl and ethynyl group, respectively, resulting in redox-active monomers, which electrochemical behaviors are tailored by the modification of the keto groups to N-cyanoimine moieties. These monomers can be polymerized by free radical polymerization and Rh-catalyzed polymerization methods, respectively. The resulting polymers are obtained in molar masses ( Mn) of 4,400 to 16,800 g mol−1 as well as high yields of up to 97%. The monomers and polymers are furthermore electrochemically characterized by cyclic voltammetry. The monomers exhibit two one-electron redox reactions at about −0.6 and −1.0 V versus Fc+/Fc. The N-cyanoimine units are, however, partially hydrolyzed during the polymerization step or during the electrochemical measurements and degenerate to carbonyl groups, resulting in a new reduction signal at −1.26 V versus Fc+/Fc. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1998-2003 [ABSTRACT FROM AUTHOR]

Poly(benzyl eugenol)(PBE) as novel ionophores for a K+ ion selective electrode was synthesized by acid catalyzed polymerization of benzyl eugenol. The polymerization product was characterized by IR and 1H NMR. The electrode membranes based on the polymer were prepared in the composition of 3 wt% of PBE, (67-n) wt% of 2- nitrophenyl octyl ether (o-NPOE) as a membrane plasticizer, n wt% of oleic acid as a lipophilic anionic additive (which n were varied from 0-10) and 30 wt% of PVC as a membrane matrix. Each membrane electrode was characterized for their performance as an ion-selective electrode membrane, that was selectivity, Nernst factor, limit of detection (l.o.d.), response time, and lifetime. Experimental results showed that the electrode membrane based on PBE with 3 wt% of oleic acid exhibited the best selectivity for K+ ion relative to other alkali and alkali earth metal ion. The K+-ISE based on PBE with the membrane composition of 3 wt% PBE, 3 wt% oleic acid, 64 wt% o-NPOE and 30 wt% PVC exhibited potentiometric selectivity toward NH4+, Na+, Mg2+, Ca2+, Ba2+ and Al3+ of -0.6; -1.3; -3.2; -2.5, -2.2 and -2.5; respectively. This electrode gave a sub- Nernstian response with a slope of 56.3 mV/decade; the response time of c.a. 30 s; the dynamic range of 10-4 - 10-1 M and limit of detection of 10-4.7 M. The electrode may be used for continuous measurement at least up to two weeks. [ABSTRACT FROM AUTHOR]

Phenolic cryogel plates (PCPs) and three-dimensional braided glass fiber reinforced phenolic cryogel composite plates (PCCPs) were successfully fabricated by microemulsion-templated sol gel polymerization and freezedrying methods. Then, pore morphology, mechanical and thermal properties of the composites were investigated. The experimental results showed that the aerogels made by freeze-drying method had the best microstructure. In addition, it was discovered that the compressive and tensile strength of the cryogel plates had equally increased for approximately 8 and 30 times after compounding with glass fiber. Simultaneously, the mechanical properties of the 20 wt% and 25% solid content (PCPs) achieved the optimal value compared with PCPs of other contents. Moreover, it was found that the cryogels had excellent thermostability, and their thermal conductivity decreased with the reducing of the solid contents, what's more, the joining of glass fiber had the increased the composites' thermal conductivity to some degree. Finally, considering the requirement of low density, good mechanical and thermal performance, the 20 wt% solid content PCCP had the best comprehensive performance compared with others. [ABSTRACT FROM AUTHOR]

An efficient type of container for anticorrosion coating based on polyaniline (PANI) modified mesoporous silica (pS) sphere has been first prepared via in-situ polymerization and surface-protected etching. The PANI-modified containers not only show higher concentration of loaded inhibitor than pS, but also protect steel well because of the PANI. The coating with 1H-benzotriazole (BTA) loaded containers shows significant anticorrosion property because of the release of BTA from containers. The structure and morphology of container are characterized by FTIR, XRD, SEM and TEM. The release of BTA from pS and PANI-modified containers is determined by UV in water. The possible self-healing anticorrosion performances are evaluated by EIS and polarization curves which indicate that the coating including BTA-loaded containers performs best. The strategy of modifying pS by PANI is effective and successful. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The synthesis of two-dimensional (2D) polymer nanosheets with a well-defined microporous structure remains challenging in materials science. Here, a new kind of 2D microporous carbonaceous polymer nanosheets was synthesized through polymerization of a very low concentration of 1,4-dicyanobenzene in molten zinc chloride at 400-500 °C. This type of nanosheets has a thickness in the range of 3-20 nm, well-defined microporosity, a high surface area (∼537 m2 g−1), and a large micropore volume (∼0.45 cm3 g−1). The microporous carbonaceous polymer nanosheets exhibit superior CO2 sorption capability (8.14 wt % at 298 K and 1 bar) and a relatively high CO2 selectivity toward N2 (25.6). Starting from different aromatic nitrile monomers, a variety of 2D carbonaceous polymer nanosheets can be obtained showing a certain universality of the ionothermal method reported herein. [ABSTRACT FROM AUTHOR]

A new method is reported herein for screening the biological activity of functional polymers across a consistent degree of polymerization and in situ, that is, under aqueous conditions and without purification/isolation of candidate polymers. In brief, the chemical functionality of a poly(acryloyl hydrazide) scaffold was activated under aqueous conditions using readily available aldehydes to obtain amphiphilic polymers. The transport activity of the resulting polymers can be evaluated in situ using model membranes and living cells without the need for tedious isolation and purification steps. This technology allowed the rapid identification of a supramolecular polymeric vector with excellent efficiency and reproducibility for the delivery of siRNA into human cells (HeLa-EGFP). The reported method constitutes a blueprint for the high-throughput screening and future discovery of new polymeric functional materials with important biological applications. [ABSTRACT FROM AUTHOR]

Moderately isospecific homopolymerization of propylene and the copolymerization of propylene and polar monomers have been achieved with palladium complexes bearing a phosphine-sulfonate ligand. Optimization of substituents on the phosphorus atom of the ligand revealed that the presence of bulky alkyl groups (e.g. menthyl) is crucial for the generation of high-molecular-weight polypropylenes (Mw≈104), and the substituent at the ortho-position relative to the sulfonate group influences the molecular weight and isotactic regularity of the obtained polypropylenes. Statistical analysis suggested that the introduction of substituents at the ortho-position relative to the sulfonate group favors enantiomorphic site control over chain end control in the chain propagation step. The triad isotacticity could be increased to mm=0.55-0.59, with formation of crystalline polar polypropylenes, as supported by the presence of melting points and sharp peaks in the corresponding X-ray diffraction patterns. [ABSTRACT FROM AUTHOR]

ABSTRACT Aiming at tuning the adsorption and fluorescence properties of targeted porous organic polymer, four new aminal-linked porous organic polymers (NAPOPs) were synthesized through the reaction of 1,4-Bis(4,6-diamino-s-triazin-2-yl) benzene (BATB) with four kinds of aldehydes substituted with different N-heterocyclic groups. Among the polymers, NAPOP-3 decorated with 5-phenyl-tetrazole group shows the largest CO2 adsorption capacity (2.52 mmol g−1 at 273 K and 100 kPa) because of its relative large surface area, while NAPOP-1 decorated with piperazine groups shows relative large CO2/N2 adsorption selectivity (77 at 273 K and 100 kPa), attributable to its large CO2 adsorption heats and cabined pore (<4 Å). Meanwhile, NAPOP-1 and −3 exhibit high adsorption rate toward iodine with a high capacity (>240 wt %). In addition, different luminescence emissions were also observed for NAPOPs, indicating different intramolecular charger transfer occurred inside polymer networks. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1724-1730 [ABSTRACT FROM AUTHOR]

ABSTRACT Polybenzimidazoles (PBI) are an important class of heterocyclic polymers that exhibit high thermal and oxidative stabilities. The two dominant polymerization methods used for the synthesis of PBI are the melt/solid polymerization route and solution polymerization using polyphosphoric acid as the solvent. Both methods have been widely used to produce high-molecular weight PBI, but also highlight the obvious absence of a practical organic solution-based method of polymerization. This current work explores the synthesis of high-molecular weight meta-PBI in N, N-dimethyl acetamide (DMAc). Initially, model compound studies examined the reactivity of small molecules with various chemical functionalities that could be used to produce 2-phenyl-benzimidazole in high yield with minimal side reactions. 1H NMR and FTIR studies indicated that benzimidazoles could be efficiently synthesized in DMAc by reaction of an o-diamine and the bisulfite adduct of an aromatic aldehyde. Polymerizations were conducted at various polymer concentrations (2-26 wt % polymer) using difunctional monomers to optimize reaction conditions in DMAc which resulted in the preparation of high-molecular weight m-PBI (inherent viscosities up to 1.3 dL g−1). TGA and DSC confirmed that m-PBI produced via this route has comparable properties to that of commercial m-PBI. This method is advantageous in that it not only allows for high-polymer concentrations of m-PBI to be synthesized directly and efficiently, but can be applied to the synthesis of many PBI derivatives. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1795-1802 [ABSTRACT FROM AUTHOR]

ABSTRACT Herein we present the synthesis and polycondensation of mono- and di- N-protected, bis-substituted tri(benzamide)s with the aim to create large, tubular helices. We synthesized 2,4-dimethoxy and 2,5-bis-TEGylated aminobenzoic acid derivatives as bent and linear monomers and introduced p-methoxybenzyl (PMB) amide protecting groups to the oligobenzamide backbone. An iterative coupling strategy allowed for sequence control, giving rise to oligomers consisting of one bent and two linear monomers. The resulting meta- para- para-linked aromatic trimers carried either one or two PMB-protecting groups. With high organosolubility and flexibility, this synthetic strategy generated suitable precursors for subsequent polycondensation reactions. After polymerization, treatment with acid triggered the cleavage of the N-protecting groups. We hypothesize that the hydrogen bonding pattern generated along the polyaramide backbone could lead to the formation of a helical polymer. A drastic change in hydrodynamic volume was observed by gel permeation chromatography and dissolution in a chiral solvent lead to the observation of a circular dichroism signal for this polymer. The results of the polycondensations of N-protected oligobenzamides are reported herein. The formation of macrocycles as well as polymers could also be observed, giving a highly interesting insight into the underlying mechanism of the polycondensation of flexible, oligobenzamide-based oligomers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1731-1741 [ABSTRACT FROM AUTHOR]

ABSTRACT Redox-active 6-oxoverdazyl polymers were synthesized via ring-opening metathesis polymerization (ROMP) and their solution, bulk, and thin-film properties investigated. Detailed studies of the ROMP method employed confirmed that stable radical polymers with controlled molecular weights and narrow molecular weight distributions ( Ð < 1.2) were produced. Thermal gravimetric analysis of a representative example of the title polymers demonstrated stability up to 190 °C, while differential scanning calorimetry studies revealed a glass transition temperature of 152 °C. Comparison of the spectra of 6-oxoverdazyl monomer 12 and polymer 13, including FT-IR, UV-vis absorption, and electron paramagnetic resonance spectroscopy, was used to confirm the tolerance of the ROMP mechanism for the 6-oxoverdazyl radical both qualitatively and quantitatively. Cyclic voltammetry studies demonstrated the ambipolar redox properties of polymer 13 ( E1/2,ox = 0.25 and E1/2,red = −1.35 V relative to ferrocene/ferrocenium), which were consistent with those of monomer 12. The charge transport properties of thin films of polymer 13 were studied before and after a potential of 5 V was applied, revealing a drastic drop in the resistivity from 106−1010 Ω m or more to 1.7 × 104 Ω m and suggesting the potential usefulness of polymer 13 in bistable electronics. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1803-1813 [ABSTRACT FROM AUTHOR]

ABSTRACT The novel polymerizable poly(alkenoic acid)s 1a-1c (expected [ABSTRACT FROM AUTHOR]