HDPE氯化原位接枝MAH及产物结构

HDPE氯化原位接枝MAH及产物结构;高密度聚乙烯;氯化原位接枝;CPE-g-MAH;接枝率;凝胶     

氯化原位接枝反应制备羟基官能化CPE——结构表征

以高密度聚乙烯(HDPE)为基体,采用气-固氯化原位接枝反应合成了以氯化聚乙烯(CPE)为骨架聚合物、丙烯酸-2羟基乙酯(HEA)为支链的接枝共聚物.反应中不需要加入任何引发剂,以氯自由基引发接枝及氯代反应,得到羟基官能化CPE接枝聚合物.并用1H-NMR,FT-IR,GPC及X-射线衍射等对接枝共聚物的结构进行了表征.     

氯化原位接枝过程与聚合物高性能化

氯化原位接枝过程是一种基于自由基反应的改性聚合物新方法,经该方法改性的聚合物性能显著改变,充分展现了弱影响、强响应的特征。本文简述了氯化原位接枝反应过程、机理,剖析了氯化原位接枝产物的结构特征,并对各类接枝共聚产物结构与性能关系进行了归纳和总结。详细介绍了各类接枝产物的不同用途,例如用于热塑性弹性体、木板粘合剂、增韧改性剂、成膜涂料等。最后对氯化原位接枝过程更广泛的应用及今后的发展趋势进行了展望。     

接枝共聚物分子设计及合成方法研究进展

接枝共聚物的主链和支链通过分子设计可以被赋予不同性质,从而使得材料拥有两种截然相反的性能.新的接枝合成方法的产生又增加了各种复杂分子结构设计的可实现性.本文围绕接枝共聚物所具有的独特结构和性能特点,详细介绍了近年来接枝共聚物在分子链和星型侧链等方面的研究现状,同时介绍了连接化学,原位氯化接枝共聚等合成方法在接枝共聚合中的应用进展,并展望了接枝共聚物的发展前景.     

CLIIR／PS接枝共聚物的相容性

本文用动态粘弹谱仪、透射电子显微镜和反相气相色谱法研究了ClIIR/PS双组份接枝共聚物的相容性。讨论了共聚物相容性与微区尺寸、玻璃化转变的关系,以及共聚物的相分离温度。     

氯化聚丙烯的熔融接枝改性及其粘接性能

氯化聚丙烯的熔融接枝改性及其粘接性能;氯化聚丙烯 甲基丙烯酸缩水甘油酯 熔融接枝 粘接     

通过反应性单体法制备聚乙烯-接枝-聚甲基丙烯酸酯和聚乙烯-接枝-聚丙烯酸

茂金属催化剂1,1′-亚乙基双茚基二氯化锆[rac-C2H4(indenyl)2ZrCl2]-MAO催化乙烯和对-烯丙基甲苯共聚合得到的共聚物为底物进行自由基溴化反应,1H-NMR表明所得的溴化聚乙烯共聚物中对-烯丙基甲苯单元两个苄基位上各有一个氢被溴取代.以此溴化聚乙烯共聚物为大分子引发剂,以CuCl/N,N,N′,N′,N″-五甲基二乙基三胺为催化剂,分别进行了甲基丙烯酸甲酯和丙烯酸叔丁酯的原子转移自由基聚合,制备出相应的聚乙烯接枝共聚物.其中,聚乙烯接枝聚丙烯酸叔丁酯共聚物在盐酸作用下可以高效水解为聚乙烯接枝聚丙烯酸共聚物,然后在氢氧化钠作用下可以进一步转化为聚乙烯接枝聚丙烯酸钠共聚物.Mulao试验表明接枝共聚物对聚乙烯的极性具有明显的改善作用.     

PEB/MMA-AN悬浮接枝共聚反应机理

研究了乙烯-1-丁烯共聚物(PEB)弹性体与甲基丙烯酸甲酯(MMA)-丙烯腈(AN)悬浮接枝共聚反应行为及接枝共聚产物对SAN树脂增韧作用随反应时间的变化规律, 用凝胶渗透色谱法和傅里叶变换红外光谱法对接枝共聚产物进行了表征, 分析了接枝共聚反应机理, 推算了接枝链分子量. 结果表明, 体系首先发生链增长自由基向PEB转移终止形成非接枝共聚物(MAN_L)和PEB大分子自由基引发单体共聚形成接枝链(g-MAN)的反应, 接枝反应结束后体系发生明显的非接枝共聚形成非接枝共聚物(MAN_H)的反应; MAN_L的分子量低于g-MAN的分子量, 而g-MAN的分子量明显低于MAN_H的分子量; 在接枝共聚过程中发生已接枝和未接枝PEB断链并随机再接生成多嵌段共聚物的副反应; 在反应初期, 接枝链的AN单元含量接近于非接枝共聚物的AN单元含量, 在反应中后期前者远低于后者.     

乙丙共聚物接枝马来酸酐反应机理的模拟研究

接枝反应;角鲨烷;乙丙共聚物接枝马来酸酐反应机理的模拟研究     

碳纤维表面酰氯化及其与尼龙6的接枝Ⅰ、接枝方法及复合材料的力学性能

碳纤维表面酰氯化及其与尼龙6的接枝Ⅰ、接枝方法及复合材料的力学性能;阴离子接枝     

Synthesis of double hydrophilic graft copolymer containing poly(ethylene glycol) and poly(methacrylic acid) side chains via successive ATRP

A well‐defined double hydrophilic graft copolymer, with polyacrylate as backbone, hydrophilic poly(ethylene glycol) and poly(methacrylic acid) as side chains, was synthesized via successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl methacrylate) side chains. The grafting‐through strategy was first used to prepare poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer. The obtained comb copolymer was transformed into macroinitiator by reacting with lithium diisopropylamine and 2‐bromopropionyl chloride. Afterwards, grafting‐from route was employed for the synthesis of poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methoxymethyl methacrylate) amphiphilic graft copolymer. The molecular weight distribution of this amphiphilic graft copolymer was narrow. Poly(methoxymethyl methacrylate) side chains were connected to polyacrylate backbone through stable C? C bonds instead of ester connections. The final product, poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methacrylate acid), was obtained by selective hydrolysis of poly(methoxymethyl methacrylate) side chains under mild conditions without affecting the polyacrylate backbone. This double hydrophilic graft copolymer was found be stimuli‐responsive to pH and ionic strength. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4056–4069, 2008     

PAA-g-PVAc Amphiphilic Graft Copolymer Synthesized by Atom Transfer Radical Polymerization

A new amphiphilic graft copolymer containing hydrophilic poly(acrylic acid) backbone and hydrophobic poly(vinyl acetate) side chains was synthesized via sequential atom transfer radical polymerization (ATRP) followed by selective hydrolysis of poly(methoxymethyl acrylate) backbone. Grafting‐from strategy was employed to synthesize PMOMA‐g‐PVAc graft copolymer (M_w/M_n=1.64) via ATRP. The final PAA‐g‐PVAc amphiphilic graft copolymer was obtained by selective acidic hydrolysis of PMOMA backbone in acidic environment without affecting the side chains. The critical micelle concentrations (cmc) in aqueous media were determined by a fluorescence probe technique. The micelle morphologies were found to be spheres.     

Novel amphiphilic graft copolymers bearing hydrophilic poly(acrylic acid) backbones and hydrophobic poly(butyl methacrylate) side chains

A novel amphiphilic graft copolymer consisting of hydrophilic poly(acrylic acid) backbones and hydrophobic poly(butyl methacrylate) side chains was synthesized by successive atom transfer radical polymerization followed by hydrolysis of poly‐(methoxymethyl acrylate) backbone. A grafting‐from strategy was employed for the synthesis of graft copolymers with narrow molecular weight distributions (polydispersity index < 1.40). Hydrophobic side chains were connected to the backbone through stable C? C bonds instead of ester connections. Poly(methoxymethyl acrylate) backbone was easily hydrolyzed to poly(acrylic acid) backbone with HCl without affecting the hydrophobic side chains. The amphiphilic graft copolymer could form stable micelles in water. The critical micelle concentration in water was determined by a fluorescence probe technique. The morphology of the micelles was preliminarily explored with transmission electron microscopy and was found to be spheres. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6857–6868, 2006     

Interactions of enzymes and a lectin with a chitin-based graft copolymer having polysarcosine side chains

The molecular-recognition abilities of a water-soluble chitin derivative, chitin-graft-polysarcosine (2) were investigated using chitinase, lysozyme, and wheat germ agglutinin (WGA). The enzymatic degradabilities of 2 were evaluated using chitinase and lysozyme. The molecular weight of those compounds of 2 with a higher affinity toward water decreased rapidly, as compared with partially deacetylated chitin (1). The 1H NMR spectrum of the low-molecular-weight fraction, yielded after lysozymic hydrolysis, indicated that saccharide residues in the chitinous backbone were specifically recognized by the lysozyme, then beta-glycosidic linkages in the backbone were selectively hydrolyzed. Furthermore, the molecular-recognition ability of the chitinous backbone of graft copolymer 2 toward the lectin WGA was elucidated by the enzyme-linked lectin-binding assay (ELLA). It was revealed that the graft copolymer with a lower degree of substitution (DS) value efficiently interacted with WGA. Interestingly, a graft copolymer having longer polysarcosine side chains showed higher recognition ability toward WGA than that having short side chains.     

A starlike amphiphilic graft copolymer with hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains

A well‐defined starlike amphiphilic graft copolymer bearing hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains was synthesized by successive atom transfer radical polymerization followed by the hydrolysis of poly‐(methoxymethyl acrylate) backbone. A grafting‐from strategy was employed for the synthesis of a graft copolymer with narrow molecular weight distribution. Hydrophobic polystyrene side chains were connected to the backbones through stable C? C bonds. The poly(methoxymethyl acrylate) backbones can be easily hydrolyzed with HCl without affecting the hydrophobic polystyrene side chains. This kind of amphiphilic graft copolymer can form stable sphere micelles in water. The sizes of the micelles were dependent on the ionic strength and pH value. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3687–3697, 2007     

Synthesis and properties of poly(ethylene oxide)‐grafted polyethylene copolymer and terpolymer

A series of graft copolymers were synthesized based on ethylene‐co‐m,p‐methylstyrene (EMS) (backbone copolymer), ethylene‐1‐hexene‐m,p‐methylstyrene (EHMS) (backbone terpolymer), and polyethylene glycol monomethyl ethers (PEGM) (grafts) in this study. The PEGMs with molecular weights of 750 and 2000 were used. The chemical composition of the graft copolymers was analyzed by NMR and DSC measurements. The graft copolymers exhibited a phase‐separated morphology with the backbone and the methoxy polyethylene glycol (MPEG) grafts forming separate crystalline phases. The MPEG phase had a melting temperature lower than the corresponding MPEG homopolymer, as determined by DSC. The melting point of the crystalline phase formed by the EMS and EHMS main chains was lower than that of pure polymer backbone. Copyright © 2009 John Wiley & Sons, Ltd.     

Random grafting statistics in graft distribution analysis

Graft distribution functions have been derived from random grafting statistics. Among the functions, the weight fraction of ungrafted backbone chains, the molecular weight distribution of the ungrafted backbone chains and the GPC apparent molecular weight distribution of the graft copolymer have been found to agree with experimental values determined for a graft copolymer system in which grafting was expected to be random. The other functions, which are not directly measurable, are therefore probably also correct. In analytical work the entire set of graft distribution functions may be computed for a graft copolymer system from the following experimental data: (1) molecular weight distribution of the starting backbone chains; (2) the chemical composition of the mixture of the graft copolymer and ungrafted backbone; (3) the graft side-chain molecular weight distribution, which may be assumed to be identical to that of the ungrafted homopolymer separable from the reaction mixture.     

聚丙烯酸接枝辛基酚聚氧乙烯醚的合成、表征和胶束化

通过自由基聚合, 丙烯酸(AA)与辛基酚聚氧乙烯醚丙烯酸酯活性大单体(C8PhEO10Ac)共聚,合成了以聚丙烯酸为主链、C8PhEO10Ac 为支链的水溶性两亲接枝共聚物(PAA-g-C8PhEO10Ac), 用凝胶渗透色谱(GPC)测定其相对数均分子质量为4.37×10⁴, 用FTIR和1H-NMR表征了共聚物的结构和组成, 共聚物分子中丙烯酸单体与活性大单体的摩尔比为9:1, 每个共聚物分子中平均约有32个C8PhEO10侧链. 用表面张力法、荧光探针法和透射电子显微镜对共聚物在水溶液中的自组装行为进行了初步研究, 结果表明, 共聚物分子在第一临界胶束浓度cmc1)和第二临界胶束浓度(cmc2)时都形成了球型胶束. 与cmc1时相比, cmc2时溶液表面张力进一步降低, 胶束内部极性进一步减小, 而且胶束粒径增大、结构紧密. 氯化钠的加入可使共聚物溶液的表面张力和胶束内部极性降低.