Synthesis and characterization of poly[(methylsilylene ethynylenephenyleneethynylene)-co-(dimethylsilylene ethynylenephenyleneethynylene)]s

<正>A series of poly[(methylsilylene ethynylenephenyleneethynylene)-co-(dimethylsilylene ethynylenephenyleneethynylene)]s were synthesized by the incorporation of various ratios of methylsilylene to dimethylsilylene units into the polymer chain backbone.The resultant copolymers were soluble in a variety of common organic solvents at room temperature.The copolymers were characterized by FT-IR,~1H-NMR,GPC,rheological analysis,differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA).The results showed that the copolymers exhibited good processability and cured at low temperatures like 200℃.The curing reactions involved in hydrosilylation of Si—H and alkyne groups and the polymerization of alkynes.Y_(d5)(5%weight loss) of the cured copolymers ranged from 629℃to 686℃,and the decomposition residues of cured copolymers at 1000℃ranged from 88.1%to 90.9%under nitrogen.Thermal stability of the copolymers increased with the introduction of methylsilylene units into polymer chains.The cured copolymers were sintered at 1450℃,and the results of X-ray diffraction analysis showed that β-SiC was formed in the sintered products.     

Synthesis and characterization of nano-sized poly[(butyl acrylate)-co-(methyl methacrylate)-co-(methacrylic acid)] latex via differential microemulsion polymerization

Poly[(butyl acrylate)-co-(methyl methacrylate)-co-(methacrylic acid)] latex particles were synthesized via differential microemulsion polymerization. The effect of initiator type and methacrylic acid incorporation were investigated. The initiator type could significantly affect the particle size and the molecular weight of the resulting polymer and 2,2′-azobisisobutyronitrile produced the smallest particle size. The incorporation of methyl methacrylate (MAA) in the copolymer and terpolymer structures was confirmed by FTIR and NMR spectroscopy, and DSC in that the carbonyl peak of carboxylic acid at 1,700 cm^?1 in the FTIR spectrum was observed when the MAA amount was high enough, the peak areas at 0.9 ppm in the NMR spectrum confirmed the participation of MAA from the increasing proton signals and the glass transition temperature and polarity of the polymer increased when the MAA amount was increased. This supported that the MAA was incorporated into the polymer chains. MAA was found to produce a vitrification effect during the polymerization.     

Synthesis and interfacial properties of a novel inverse demulsifier of nanosized poly[(methyl methacrylate)-co-(ethyl acrylate)-co-(methacrylic acid)-co-(acrylamide)] latex

An acrylic emulsion-type inverse demulsifier (named as PMEMA latex) was prepared by using methyl methacrylate (MMA), ethyl acrylate (EA), methacrylic acid (MAA), and acrylamide (AM) as monomers. The effects of reaction conditions toward the copolymerization results were investigated by evaluating various evaluation parameters, including conversion, molecular weight, and diameter. In addition, the interfacial properties of PMEMA latex were investigated to study its demulsification mechanism about treating the O/W emulsion.     

The synthesis of poly(3,4-dihydroxystyrene) and poly[(sodium 4-styrenesulfonate)-co-(3,4-dihydroxystyrene)]

Poly(2-methoxy-4-vinylphenol), polyMVP, and poly[(sodium 4-styrenesulfonate)-co-(2-methoxy-4-vinylphenol)], poly(SSS/MVP), were synthesized by radical polymerization using Vazo-64 or tributylborane as initiator. Poly(3,4-dihydroxystyrene) and poly[(sodium 4-styrenesulfonate)-co-(3,4-dihydroxystyrene)] were obtained by demethylation of polyMVP and poly(SSS/MVP) using HBr and trimethylsilyl iodide, respectively. (Co)polymer structures were confirmed by ¹H and ¹³C NMR spectra. About 30 wt.-% gel formed in the polyMVP polymerizations, whereas only a small amount (0.5 mol-%) of gel formed in the copolymerizations.     

Grafting reactions of vinyl acetate onto poly[(vinyl alcohol)-co-(vinyl acetate)]

The grafting preference of vinyl acetate onto the methine carbon of poly(vinyl alcohol) (PVOH) versus the acetate group of poly(vinyl acetate) (PVAc) was determined as part of an attempt to prepare novel branched PVOH from partially hydrolyzed PVAc. The results showed long chain grafting on the acetate groups of the PVAc units rather than the methine carbons of the PVOH or PVAc units. Decreasing the monomer or initiator concentration decreased the molecular weight of the graft copolymer formed. Of the initiators studied, ammonium persulfate gave the largest increase in copolymer molecular weight. Both hydrolysis and reacetylation combined with gel permeation chromatography (GPC) and ¹³C-NMR of the fully hydrolyzed material were used to estimate the number and location of grafts. © 1996 John Wiley & Sons, Inc.     

Conjugation of bioactive groups to poly(lactic acid) and poly[(lactic acid)-co-(glycolic acid)] films

A novel PLA-based polymer containing reactive pendent ketone or hydroxyl groups was synthesized by the copolymerization of L-lactide with epsilon-caprolactone-based monomers. The polymer was activated with NPC, resulting in an amine-reactive polymer which was then cast into thin polymeric films, either alone or as part of a blend with PLGA, before immersion into a solution of the cell adhesion peptide GRGDS in PBS buffer allowed for conjugation of GRGDS to the film surfaces. Subsequent 3T3 fibroblast cell adhesion studies demonstrated an increase in cellular adhesion and spreading over films cast from unmodified PLGA. Hence the new polymer can be used to obtain covalent linkage of amine-containing molecules to polymer surfaces.     

Investigation on poly[(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)]

<正>Poly[(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)]was synthesized by polycondensation reaction of m-diethynylbenzene magnesium reagent with 1,3-dichlorotetramethyldisiloxane and dichloromethylsilane.The copolymer was characterized by FT-IR,~1H NMR,differential scanning calorimetry and thermogravimetric analysis.The results show that the copolymer exhibits good processability and cures at low temperatures.The cured copolymer shows high thermal stability.     

交联型聚芳醚砜两亲嵌段聚合物的合成与表征

首先分别合成了主链上含有查尔酮结构的疏水段和侧链上含有叔胺的亲水段,然后通过疏水段与亲水段的末端缩合反应合成了一系列光敏性聚芳醚砜两亲嵌段聚合物,其结构和热性能分别通过1 H NMR,FT-IR,UV-Vis光谱,TGA和万能力学试验机等进行表征测试.该两亲性嵌段聚合物具有良好的溶解性、热稳性、力学性能和光敏性,在紫外光谱322nm处有最大吸收峰,在常温下经紫外光照射,分子链之间发生[2+2]环加成反应,聚合物分子之间形成交联结构,最大交联度可达到64%.     

Separation of statistical poly[(N-vinyl pyrrolidone)-co-(vinyl acetate)]s by reversed-phase gradient liquid chromatography

Although size exclusion chromatography (SEC) has been used successfully to determine the molecular weight distribution (MWD) of statistical poly[(N-vinyl pyrrolidone)-co-(vinyl acetate)]s [PVPVAs], SEC cannot separate the copolymers according to their chemical composition. In this article, the separation of commercial PVPVAs with varying chemical compositions is reported, by aqueous reversed-phase gradient liquid chromatography (RPLC) using polystyrene-divinylbenzene-based wide pore columns. RPLC-SEC cross-fractionation indicates the presence of molar mass dependant effects during RPLC separation due to broad MWD for the copolymer studied; therefore the width of the RPLC peak could not be associated entirely with chemical composition distribution of the copolymer. Coupling of RPLC with online FTIR spectroscopy reveals the increase of VA content with increasing THF gradient, an indication of interaction mechanism between VA repeating units and the stationary phase for water soluble PVPVAs. Separation of water insoluble PVPVAs and PVAs by the RPLC are possibly based on both interaction and precipitation/redissolution mechanisms.     

Immobilization of penicillin G acylase on poly[(glycidyl methacrylate)-co-(glycerol monomethacrylate)]-grafted magnetic microspheres

Poly[(glycidyl methacrylate)-co-(glycerol monomethacrylate)]-grafted magnetic microspheres were prepared by graft random copolymerization via ATRP from polymer microspheres with dispersed Fe(3)O(4) nanoparticles. Penicillin G acylase (PGA) was immobilized onto the polymer brush-grafted magnetic microspheres. The immobilized PGA prepared with initial glycidyl methacrylate/glycerol monomethacrylate ratios of 40/60 to 60/40 possessed higher catalytic activity than that prepared with higher proportions of glycidyl methacrylate in the initial monomer mixture. The immobilized PGA showed high thermal stability and enhanced tolerability to the pH variance.     

Synthesis of novel core‐crosslinked graft copolymers from crosslinked poly(mercapto‐thiourethane)

Crosslinked poly(mercapto‐thiourethane) was employed as a precursor for graft copolymer synthesis. The crosslinked stem polymer ( 1 ) was easily prepared by polyaddition of a bifunctional dithiocarbonate and piperazine under air atmosphere via oxidative coupling of mercapto group. Polymerization of styrene and methyl methacrylate in the presence of 1 yielded the corresponding crosslinked graft copolymers with high grafting weight percentages (>1800%). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5097–5102, 2005     

Lipase-catalyzed synthesis and properties of poly[(12-hydroxydodecanoate)-co-(12-hydroxystearate)] directed towards novel green and sustainable elastomers

Novel green and sustainable elastomers having both good biodegradability and chemical recyclability properties were designed and synthesized using potentially biobased materials and lipase as an environmentally benign catalyst. High molecular weight poly[(12-hydroxydodecanoate)-co-(12-hydroxystearate)] [poly(12HD-co-12HS)] samples with varying monomer ratios were prepared by the polycondensation of 12-hydroxydodecanoic acid and methyl 12-hydroxystearate using immobilized lipase from Candida antarctica (IM-CA) in toluene in the presence of molecular sieves 4A at 90 degrees C. Although poly(12HD) is a highly crystalline polyester having a melting temperature (T(m)) of 87.6 degrees C and crystalline temperature (T(c)) of 64 degrees C, by the copolymerization of 12HD with 12HS, both the T(m) and T(c) of the copolymer decreased with increasing 12HS contents, and poly(12HD-co-12HS) containing more than 60 mol-% 12HS was a viscous liquid at room temperature. At the same time, the Young's modulus and hardness also decreased with increasing 12HS content, and poly(12HD-co-36 mol-% 12HS) exhibited an elastic behavior, having a hardness of 70 A using a durometer A. In addition, it showed an excellent biodegradability by activated sludge and chemical recyclability by lipase.     

Influence of the solvent on the spreading of poly[(D,L-lactic acid)-co-(glycolic acid)] monolayers

 The properties of mono layers of poly[(D,L-lactic acid)-co-(glycolic acid)] (PLA/GA) are strongly conditioned by the nature of the solvent from which they are spread. In this work, we studied the properties of PLA/GA films deposited on water from acetonitrile (a poor spreading solvent) and chloroform (a good one), observing marked differences with regard to the influence of the pH, temperature and ionic strength of the subphase. These differences were attributed to the structure of PLA/GA at the air/water interface, being pre-determined by its structure in the bulk spreading solvent (closely coiled in acetonitrile, unfolded in chloroform). Viscosity measurements on acetonitrile and chloroform solutions of PLA/GA, and the calculation of the corresponding intermolecular expansion factor, α, confirmed that PLA/GA was better solvated by chloroform than by acetonitrile, in which intramolecular interactions between polymer segments, and thus coiling, will therefore have predominated over polymer–solvent interactions. Received: 14 October 1996 Accepted: 7 January 1997     

Mechanical properties of comonomer-compositionally fractionated poly[(3-hydroxybutyrate)-co-(3-mercaptopropionate)] with low 3-mercaptopropionate unit content

The mechanical properties, such as Young's modulus, yield strength, and the elongation at breakage, were investigated for several sulfur-containing biopolymers P(3HB-co-3MP). A series of P(3HB-co-3MP) samples with 3MP unit content ranging from 6.6 to 39.1 mol-% was biosynthesized by fermentation using the PHA-synthesizing bacteria Cupriavidus necator. For comparison, the bacterially synthesized P(3HB) and P(3HB-co-3HP) with the 3HP unit content ranging from 13.1 to 21.1 mol-% were also investigated. It was found that the sulfur-containing P(3HB-co-3MP) is much more durable to stretching. Notably, P(3HB-co-3MP) with the 3MP unit content of only 6.6 mol-% was found to show excellent mechanical properties.     

Highly branched stimuli responsive poly[(N-isopropyl acrylamide)-co-(1,2-propandiol-3-methacrylate)]s with protein binding functionality

Highly branched poly(NIPAM) have been prepared using the technique of reversible addition-fragmentation chain transfer (RAFT) polymerisation using a chain transfer agent that allows the incorporation of imidazole functionality in the polymer chain-ends. The lower critical solution temperature (LCST) of the polymers can be controlled by the amount of hydrophobe and GMA incorporated during copolymerisation procedures. These thermally responsive "smart" polymers were used to purify a His-tagged BRCA-1 protein fragment by affinity precipitation. [Diagram: see text]