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The synthesis and antibacterial properties of N-halamine copolymers are reported in this paper. 3-(4′-vinylbenzyl)-5,5-dimethylhydantoin (VBDMH) monomer and its copolymers with n-butyl methacrylate (BMA) were prepared under mild conditions. The effects of monomer feeds on the composition of the final copolymers and reaction conversion were investigated. It was found that VBDMH had higher reactivities than BMA in the copolymerization reactions and the reactivity ratios of VBDMH and BMA were calculated to be 8.91 and 0.42, respectively, according to the Fineman–Ross equation in the preparation of PBMA-co-VBDMH. Two chlorination methods were applied and compared in the process of polymers chlorination. After chlorination by tert-butyl hypochlorite, the polymers provided powerful antibacterial activities against Escherichia coli ( E. coli). The surface morphologies of the chlorinated polymer films used in antibacterial assessment were observed by scanning electron microscope. The copolymers before and after chlorination were characterized with fourier transform infrared (FTIR) and 1H-nuclear magnetic resonance (1H-NMR). Their thermal properties were analyzed with thermogravimetric analysis (TGA) studies. [ABSTRACT FROM AUTHOR]

This paper describes the polymer modification of road bitumens with SBS. Six polymer modified bitumens (PMBs) were produced by mixing bitumen from two crude oil sources with an SBS copolymer at three polymer contents. The rheological characteristics of the SBS PMBs were analysed by means of dynamic mechanical analysis using a dynamic shear rheometer (DSR). The results of the investigation indicate that the degree of SBS modification is a function of bitumen source, bitumen-polymer compatibility and polymer concentration. When the polymer concentration and bitumen-polymer compatibility allow a continuous polymer network to be established, modification is provided by a highly elastic network which increases the viscosity, stiffness and elastic response of the PMB, particularly at high service temperatures. However, ageing of the SBS PMBs tends to result in a reduction of the molecular size of the SBS copolymer with a decrease in the elastic response of the modified road bitumen. [ABSTRACT FROM AUTHOR]

Conducting polymers represent a promising platform toward coating materials for implant technologies in recent years. In this investigation, copolymers based on pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) were electrodeposited on 316L SS with various feed ratio of Py/EDOT through cyclic voltammetric technique. The surface and chemical structure of the synthesized copolymers were analyzed by SEM, AFM, FT-IR, and H NMR spectroscopic analysis. The influence of comonomer feed ratio on electrochemical corrosion behavior was investigated in stimulated body fluid. A significant lower corrosion current with nobler shift in corrosion potential and higher charge transfer resistance values of copolymer-coated 316L SS were obtained and the comparisons were made with uncoated as well as their homo polymers. Furthermore, in vitro cell culture studies were performed on MG63 osteoblast human cells to confirm the biocompatibility of copolymer coatings. Quantum chemical approach was employed to verify the obtained experimental outcomes. As a result of this investigation, it was concluded that the performance of coatings was strongly dependent to the monomer feed ratio and the copolymer synthesized with 50:50 feed ratio showed high corrosion protection efficiency with improved cell growth on MG63 osteoblast cell. [ABSTRACT FROM AUTHOR]

Composites of pyroelectric ceramics and polymers are very important as their unique features and properties can be easily tailored for various specific applications. Lithium tantalatum oxide (LiTaO3, LT), the pyroelectric ceramic powder has been incorporated into a polyvinylidene fluoride–trifluoroethylene [P(VDF–TrFE) 70/30 mol%] copolymer matrix to form 0–3 composites. The composite films were prepared using ‘solvent casting’ (SC) method to disperse the ceramic powder homogeneously in the P(VDF–TrFE) copolymer matrix with various wt% of LT powder. In order to derive high pyroelectric performance, the samples were poled. Electric properties, such as the dielectric constant, dielectric loss, and pyroelectric coefficient, have been measured as a function of temperature and frequency. In addition, material figures-of-merit, very important factors for assessing many sensor applications have also been calculated. The results show that the fabricated lead free lithium tantalite: P(VDF–TrFE) composite materials have a good potential for pyroelectric infrared sensor applications. [ABSTRACT FROM AUTHOR]

Two new cyano-substituted copolymers containing biphenylenevinylene and bithienylenevinylene moieties (DCN-PPV and DCN-PTV) were synthesized by a stille condensation reaction with Pd(PPh3)4 as catalyst. Their structures were confirmed by 1H NMR, IR spectroscopy, and elemental analysis. The thermal, optical, and electrochemical properties of the polymers were investigated. The results show that the polymers possess high thermal decomposition temperature and reversible n-doping/dedoping processes. In addition, DCN-PTV has higher electron affinity with a low LUMO energy level of −3.84 eV and a relatively broader absorption band covering 300–780 nm, indicating that DCN-PTV could be a potential n-type conjugated polymer in optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this contribution thermosensitive polymer matrices based on N-isopropylacrylamide have been developed. The hydrogels were prepared by photopolymerisation of N-isopropylacrylamide and 1-vinyl-2-pyrrolidinone in appropriate amounts of distilled water. The monomers were cured using a UV-light sensitive initiator called 1-hydroxycyclohexylphenylketone. These copolymers were crosslinked using ethylene glycol dimethacrylate and poly(ethylene glycol) dimethacrylate with molecular weights 600 and 1,000, at 0.1 wt% of the total monomer content. The chemical structure of the xerogels was characterised by means of Fourier transform infrared spectroscopy (FTIR) and the transition temperature of the hydrogels was determined using modulated differential scanning calorimetry (MDSC). By altering the feed ratio, hydrogels were synthesised to have lower critical solution temperatures (LCST) around 37 °C. This ability to shift the phase transition temperature of the gels provides excellent flexibility in tailoring transitions for specific uses. The samples synthesised with PEG1000DMA crosslinking agents absorbed over 18 times their weight in water, while maintaining good gel integrity thus falling marginally short of being characterised as superabsorbent. Each of the samples showed similar deswelling behaviour at 37 °C. Rheological studies showed that increasing the molecular weight of the crosslinking agent caused an increase in hydrogel strength. [ABSTRACT FROM AUTHOR]

Hafnium-organic moiety hybrid copolymers were prepared by reacting hafnium n-butoxide with organic diols. ESR spectral examinations of copolymers and ab-initio calculations of copolymer models suggest that an electron transfer from organic group to hafnium atom takes place. [ABSTRACT FROM AUTHOR]

A novel copolymer, poly[9-(4′-tert-butyl-phenylenemethene)-fluoroene-co-9,9-dioctylfluorene], has been synthesized through the Yamamoto coupling method. The copolymer has good solubility and thermal stability with a glass transition temperature at 85 °C. The PL spectrum of the copolymer shows a maximum emission peak at 530 nm. A polymer light-emitting diode (PLED) with the configuration ITO/PEDOT/copolymer/Ca/Al has been fabricated. The device emits green light with an emission peak at 540 nm. A maximum brightness of 603 cd/m2 was achieved at a drive voltage of 24.3 V. [ABSTRACT FROM AUTHOR]

This study was designed to determine the linear viscoelastic and extrusion properties of a series of LDPE/EVAc blends. Newtonian viscosity was found to show strong positive deviation from the double reptation model, which assumes miscibility or, at least, cooperative relaxation between the mixed species. The blends also showed enhanced steady-state compliance and elastic indices compared to those of the pure components. These features, typical of emulsion-like polymer blends, seem to be attributable to additional relaxation processes at low frequencies associated with dispersed phase deformability. Good agreement with experimental dynamic results was shown by the Palierne model for emulsions of two viscoelastic liquids, for values of α/ R = 3.5 × 103 Pa across the whole frequency range examined. The double reptation model, usually applied to miscible blends, showed good agreement with experimental data for frequencies higher than 10−2 rad s−1. This could lead to erroneous conclusions on the miscibility of certain systems, for which a complete set of experimental data is lacking. [ABSTRACT FROM AUTHOR]

The phase characteristics of vinylidene fluoride (VDF) segments in vinylidene fluoride (VDF) and hexafluoropropylene (HFP) copolymer (PVDF-HFP) under different quenching temperature were investigated by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) measurements. It was found that the α and β crystalline phases of VDF segments formed in PVDF-HFP as those in pure PVDF. Compared with pure PVDF, HFP segments affected the β phase formation obviously. Increasing of quenching temperature would decrease the fraction of β phase in the quenched PVDF-HFP films, and the films thicker than 8 μm were not in favor of the β phase transformation. Blending PVDF-HFP with small amounts of PMMA (≤10 wt%) yielded great effects on the crystal phase of VDF segments. But higher blending degree of PMMA couldn't increase the formation of β phase further. [ABSTRACT FROM AUTHOR]

Dielectric response of vinylidene fluoride type ferroelectric polymers is dominated by that of segmental motions in the amorphous phase in temperature range 200–300 K and contributions related to the local mode and ferroelectric–paraelectric transition in the crystalline phase of the polymer at higher temperatures. Diffuse and frequency-dependent dielectric anomaly observed in fast electron irradiated polyvinylidene fluoride-trifluoroethylene P(VDF/TrFE) has been related to relaxor-like behavior induced in the semicrystalline ferroelectric copolymers. As random field and the response of polar nanosize clusters determine the relaxor behavior the effects of disorder and fast electron irradiation (below and above T C) on the three contributions to the dielectric response of PVDF, P(VDF/TrFE)(75/25) and P(VDF/TrFE)(50/50) are shown. The processes involved in radiation-induced functionalization of PVDF-type polymers are discussed on the basis of results of ESR, IR and Raman spectroscopy studies. [ABSTRACT FROM AUTHOR]

To elucidate the molecular origin of the polarization dynamics in the ferroelectric relaxor poly(vinylidene fluoride—trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer, a broadband dielectric study was carried out in the frequency range from 0.01 Hz to 10 MHz and temperatures from −150°C to 120°C for the terpolymer and a normal ferroelectric P(VDF-TrFE) copolymer. The relaxation processes were also studied using dynamic mechanical analysis. It was shown that in the terpolymer, which was completely converted to a ferroelectric relaxor, there is no sign of the relaxation process associated with the ferroelectric-paraelectric transition which occurs in the P(VDF-TrFE) copolymer. In the copolymer, three additional relaxation processes have been observed. It was found that the relaxation process βa, which was commonly believed to be associated with the glass transition in the amorphous phase, in fact, contains significant contribution from chain segment motions such as domain boundary motions in the crystalline region. In the temperature range studied, the terpolymer exhibits the latter three relaxation processes with the one (termed βr) near the temperature range of βa significantly enhanced. This is consistent with the observation that in conversion from the normal ferroelectric to a ferroelectric relaxor, the macro-polar domains are replaced by nano-polar-clusters and the boundary motions as well as the reorientation of these nano-clusters generate the high dielectric response. The experimental data also reveal a broad relaxation time distribution related for the βr process whose distribution width increases with reduced temperature, reflecting the molecular level heterogeneity in the crystalline phase due to the random introduction of the CFE monomer in the otherwise ordered macro-polar domains. The random interaction among the nano-clusters as well as the presence of the random fields produces ferroelectric relaxor behavior in the terpolymer. [ABSTRACT FROM AUTHOR]

The effect of high-energy electron-irradiation on binary ferroelectric blends of poly(vinylidene fluoride-trifluoroethylene) 56/44 and 80/20 mol% has been studied in a broad dose ranging from 0 to 120 Mrad. It was found that the blends transformed from a normal ferroelectric to relaxor ferroelectric, obeying the Vogel-Fulcher law, after a proper electron dose by dielectric constants and loss measurements. X-ray diffraction shows significant changes in the ferroelectric-to-paraelectric phase transition behavior from all-trans to trans-gauche conformation after irradiation. In differential scanning calorimetry (DSC) thermograms, the Curie temperature and melting temperature decrease with the dose, indicating that there exists a strong lattice coupling between the two copolymers. [ABSTRACT FROM AUTHOR]

Asymmetric styrene/butadiene block copolymers and their blends with polystyrene homopolymer are studied, using transmission electron microscopy and scanning force microscopy, to explore the influence of phase morphology on the microindentation hardness and the nano-mechanical deformation mechanisms. In contrast to polymer blends and random copolymers, in which microhardness generally follows the additivity law, the behaviour of the investigated block copolymer systems is found to significantly deviate from the hardness additivity behaviour. Owing to the modified architecture, the asymmetric star block copolymer having 74 vol% polystyrene possesses a lamellar morphology, which partly explains the observed low hardness values. An additional explanation is found in the large plastic homogeneous deformation of the polystyrene (PS) lamellae by means of a new micromechanical mechanism called thin layer yielding. In the blends of a star block copolymer with polystyrene homopolymer, a rapid change in the micromechanical deformation behaviour is found to cause a shift in the observed microhardness to larger values. A major conclusion of our investigations is that microhardness of the triblock and star block copolymers can only be explained in the light of the morphology and nano-mechanical deformation mechanisms involved. [ABSTRACT FROM AUTHOR]

When researching the effect of rubber toughening in acrylonitrile-butadiene-styrene (ABS) copolymer and high-impact polystyrene (HIPS) and also toughening methods used in other materials, then, often comparisons are needed between materials with and without the toughening agents over the full crack velocity range. This is from the threshold stress to just maintain crack propagation up to the limiting crack velocity conditions. However, the toughening of materials can change other material properties including, for example, the onset of yield in the material under static stress. The result can be that a crack velocity versus stress curve cannot be obtained by experiment over the full crack velocity range for some toughened materials. However, as used in this study, combined experimental and computer simulations can provide for a meaningful and informative comparison between crack velocity versus stress curves for materials with and without toughening agents over the full crack velocity range. [ABSTRACT FROM AUTHOR]

The article reports on simultaneous measurement of rheological and conductive properties of carbon black filled ethylene-tetrafluorothylene copolymer. It is posed that composites composed of carbon black (CB) filled polymers have been widely used in many field such as electromagnetic/radio-frequency interference shielding, conductive adhesives for die attachment in electrostatic discharge, electroactive polymeric sensors in hand prostheses, and electrostatic discharge. It is also forwarded that the morphology and properties of filled polymer composites are greatly affected by the state of filler dispersion. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used in identifying the structure and morphology of fillers.

The article reports on the syntheses and the electronic behaviors of alternating indium-organic moiety binary hybrid copolymers. The authors claim that indium is an important key atom in the field of electronic and photochemical industries and the authors assumed that an indium-organic moiety hybrid material is expected to show unique properties.