Thermally stable interpenetrating polymer networks for second-order nonlinear optical materials

We report several kinds of interpenetrating polymer networks (IPNs) with nonlinear optical (NLO) properties. DMA spectra show that the two components of the IPNs have good compatibility with each other. The NLO materials have good optical transparency. The thermal stability of alignment was improved and the poled order remained very high. (C) 1999 John Wiley & Sons, Inc.

Lithium ion conducting polymer electrolytes based on alternating maleic anhydride copolymer with oligo-oxyethylene side chains

A comb polymer with oligo-oxyethylene side chains of the type -(CH2CB2O)(12)CH3 was prepared from methyl vinyl ether/maleic anhydride copolymer and poly (ethylene glycol) methyl ether. The polymer can dissolve LiClO4 salt to form homogeneous amorphous polymer electrolyte. The ac ion conduction was measured using the complex impedance method, and conductivities were investigated as functions of temperatures and salt concentration. The complexes were first found to have two classes of glass transition which increase with increasing salt content, The optimum conductivity attained at 25 degrees C is in the order of 5.50 x 10(-6)Scm(-1). IR spectroscopy was used to study the cation-polymer interaction.

Compatibilization effect of graft copolymer on immiscible polymer blends .2. LLDPE/PS/LLDPE-g-PS systems

The compatibilizing effect of graft copolymer, linear low density polyethylene-g-polystyrene (LLDPE-g-PS), on immiscible LLDPE/PS blends has been studied by means of C-13 CP-MAS NMR and DSC techniques. The results indicate that LLDPE-g-PS is an effective compatibilizer for LLDPE/PS blends, and the compatibilizing effect of LLDPE-g-PS on LLDPE/PS blends depends on the PS grafting yield and molecular structure of the compatibilizers and also on the composition of the blends. It was found that LLDPE-g-PS chains connect two immiscible components, LLDPE and PS, through solubilization of chemically identical segments of LLDPE-g-PS into the noncrystalline region of the LLDPE and PS domain, respectively. Meanwhile, LLDPE-g-PS chains connect the crystalline region of LLDPE by isomorphism, resulting in an obvious change in the crystallization behavior of LLDPE. (C) 1996 John Wiley & Sons, Inc.

Polymer-supported titanium catalysts for syndiotactic polymerization of styrene

Poly(styrene-co-acrylamide) (PSAm)-titanium complexes (PSAm . Ti) were prepared and characterized. It is found that the coordination number of acrylamide (Am) to Ti in the complexes is strongly dependent on Am content in PSAm, but not on [Am]/[Ti] ratio in the feed. The infrared and x-ray photoelectron spectra suggest that the polymer-supported complexes possess the structure [GRAPHICS] The catalytic behavior of the complexes in styrene polymerization is described. The catalytic activity is markedly affected by [Al]/[Ti] ratio in the complexes. C-13 NMR, IR, and DSC data indicate that the polystyrene obtained with PSAm . Ti/MAO (MAO = methylaluminoxane) is highly syndiotactic. Use of Et(3)Al and i-Bu(3)Al in place of MAO gives atactic polystyrene. The activities of the various aluminum compounds used as the cocatalysts decrease in the order: MAO > Et(3)Al > i-Bu(3)Al. The polymer-supported complexes show relatively high activity even after the complexes had been exposed to air for 19 h or higher polymerization temperature. (C) 1996 John Wiley & Sons, Inc.

Studies on water-swellable elastomer .1. Synthesis and characterization of amphiphilic polymer

A new amphiphilic polymer i.e., polyethylene glycol (PEG) grafted crystalline neoprene, which was used as compatibilizer to improve the compatibility of elastomer and water-absorbent resin, has been investigated. The synthesis was based on the reaction between chlorine in neoprene and sodium salts of PEG. PEGs with molecular weights of 600 and 2000 were used. The grafting percent and the PEG content were calculated through elemental analysis of chlorine in the resulted copolymers. The maximum grafting percent of copolymers was ca. 24.80%. The molecular parameters such as number-average molecular weight and the average number of grafting chains on one CR backbone were also calculated and discussed. (C) 1996 John Wiley & Sons, Inc.

Toughening mechanism of polymer blends: Influence of voiding ability of dispersed-phase particles

The parameters which effect the cavitation strain of polymer blends toughened with a shear yield mechanism have been studied by analysis of the stress acted on the equatorial plane of dispersed-phase particles. As a result, the cavitation strain of polymer blends depends on the Young's modulus and the Poisson's ratio of the dispersed-phase particles and the matrix and also on the break stress of dispersed-phase particles. We tried to provide a criterion for selecting the materials used as dispersed-phase particles which can effectively enhance the toughness of polymer blends. (C) 1996 John Wiley & Sons, Inc.

SYNTHESIS AND CHARACTERIZATION OF A NEW COMB-LIKE POLYMER-BASED ON POLY(VINYL METHYL ETHER-ALT-MALEIC ANHYDRIDE) BACKBONE

A new comblike polymer host for polymer electrolyte was synthesized by reacting monomethyl ether of poly(ethylene glycol) with poly(vinyl methyl ether-alt-maleic anhydride) and endcapping the residual carboxylic acid with methanol. Butanone was selected as a solvent for the esterification in order to obtain a completely soluble product. The synthesis process was traced through by LR. Compared with the model compounds, the presumed structure of this comblike polymer has been proved to be valid by C-13 NMR The comb polymer is a white rubbery solid. It can be dissolved in butanone and THF, and manifests good film forming ability.

EFFECT OF PARTICLE-SIZE ON IMPACT STRENGTH OF POLYMER BLENDS

The effect of particle size on impact strength of polymer blends with ductile fracture was studied. The results are in agreement with the experiments. (C) 1995 John Wiley & Sons, Inc.

AN EXTENSION OF THE METHOD FOR PREDICTING PERMEABILITY THROUGH POLYMER MEMBRANES FROM SIMPLE GASES TO WATER-VAPOR

It is found that there is a linear relationship between log P-w, and the parameter term V-f/0.5 E(coh) [1+(delta(w) - delta(p))(2)/delta(p)(2), from the water permeability (P-w) data of 21 polymers covering 4 orders of magnitude. This correlation may be useful in choosing membrane materials for dehumidification of gases.

FRACTURE-TOUGHNESS AND MORPHOLOGY OF PHENOLPHTHALEIN POLY(ETHER SULFONE) THERMOTROPIC LIQUID-CRYSTALLINE POLYMER BLENDS

Blends of a new phenolphthalein poly (ether sulfone) (PES-C) and a thermotropic liquid crystalline polymer (LCP) were prepared by melt-blending in a twin-screw extruder. Rheological properties, fracture toughness, K(IC), and morphology of the blends were

ENTANGLEMENT FLUCTUATION DURING PHASE-SEPARATION IN POLYMER BLENDS

For perhaps the first time, the dynamics of liquid-liquid phase separation was studied by time-resolved mechanical spectrometry in order to establish the relationship between blends' properties and the phase structures during spinodal decomposition (SD). The selected system was chlorinated polyethylene (CPE)/ethylene-vinyl acetate copolymer (EVA). It was found that in the early and intermediate stage of SD, the storage modulus (G') and the loss modulus (G'') increase with time after the initiation of the isothermal phase separation; in the later stage, G' and G'' decrease as phase separation proceeds. An entanglement fluctuation model was presented to manifest this phenomenon; it was found that the rheological behavior agrees well with the expections of the model in the early stage. For the later stage, the reduction of G' and G'' can be attributed to the increment of phase-domain size. (C) 1993 John Wiley & Sons, Inc.

Degradable Polymer Networks and Star Polymers Based on Mixtures of Two Cleavable Dimethacrylate Crosslinkers: Synthesis, Characterization, and Degradation

Mixtures of two cleavable dimethacrylate crosslinkers, the hydrolyzable di(methacryloyloxy-1-ethoxy)methane (DMOEM) and the thermolyzable 1,1-ethylene-diol dimethacrylate (EDDMA), were used for the preparation of neat crosslinker polymer networks, randomly crosslinked polymer networks of methyl methacrylate (MMA), and star polymers of MMA, using group transfer polymerization in tetrahydrofuran (THF). All star polymers and randomly crosslinked polymer networks containing mixtures of the hydrolyzable DMOEM and the thermolyzable EDDMA crosslinkers gave THF-soluble final products when subjected to sequential thermolysis and hydrolysis, in this order. When applying sequential hydrolysis and thermolysis, only the star polymers with an EDDMA crosslinker content equal to or higher than 50% gave THF-soluble final products.

Thermolyzable polymer networks and star polymers containing a novel, compact, degradable acylal-based dimethacrylate cross-linker: Synthesis, characterization, and thermolysis

A compact, cleavable acylal dimethacrylate cross-linker, 1,1-ethylenediol dimethacrylate (EDDMA), was synthesized from the anhydrous iron(III) chloride-catalyzed reaction between methacrylic anhydride and acetaldehyde. The ability of EDDMA to act as cross-linker was demonstrated by using it for the preparation of one neat cross-linker network, four star polymers of methyl methacrylate (MMA), and four randomly cross-linked MMA polymer networks using group transfer polymerization (GTP). For comparison, the corresponding polymer structures based on the commercially available ethylene glycol dimethacrylate (EGDMA) cross-linker (isomer of EDDMA) were also prepared via GTR The number of arms of the EDDMA-based star polymers was lower than that of the corresponding EGDMA polymers, whereas the degrees of swelling in tetrahydrofuran of the EDDMA-based MMA networks were higher than those of their EGDMA-based counterparts. Although none of the EDDMA-containing polymers could be cleanly hydrolyzed under basic or acidic conditions, they could be thermolyzed at 200 degrees C within 1 day giving lower molecular weight products.