新引发体系引发MMA活性自由基聚合

近年来 ,关于活性自由基聚合的研究极为活跃 ,已经发现了多种基于增长链自由基被可逆钝化形成休眠种的活性自由基聚合方法[1,2 ] .它们主要包括引发转移终止剂 ( Iniferter) ,稳定自由基聚合( SFRP) ,原子转移自由基聚合 ( ATRP) ,可逆加成 -断链链转移聚合 ( RAFT)等 .其中 ATRP因其具有可聚合单体多 ,反应条件相对缓和等优点而成为该领域的研究热点 [3～ 5] .ATRP活性自由基聚合的实现主要是在过渡金属催化剂的作用下 ,通过循环往复的碳 -卤键的活化、加成、碳 -卤键的再形成而得到最终活性的聚合物 ,引发体系由引发剂、过渡金属…     

“活性”/控制自由基聚合的研究进展

本文对“活性”／控制自由基聚合的研究进展做了综述,并讨论了其主要聚合引发体系的应用现状和前景。     

SYNTHESIS AND POLYMERIZATION OF α-METHACRYLYOXYLETHYLOXYCARBONYLMETHYL-ω-(N,N-DIETHYLDITHIOCARBAMYL)POLYSTYRENE MACROMONOMERS

Polystyrene macromonomers with different molecular weight were prepared by radical polymerization of styrene(St) in benzene using β-methacryloxylethyl 2-N,N-diethyldithiocarbamylacetate (MAEDCA) as a monomer-iniferter.Characterization of the macromonomer by ~1H-NMR showed that the end groups were α-methacrylyoxylethyloxycarbonyl-methyl and ω-(N,N-diethyldithiocarbamyl). The macromonomer was difficult to homopolymerize, but it was easilycopolymerized with methyl methacrylate (MMA) initiated by AIBN to form graft copolymers (PMMA-g-PSt) with PStbranches randomly distributed along the PMMA backbone. Copolymerization reaction and the structure of the graftcopolymers were strongly affected by M_n and concentration of the macromonomer. The composition and M_n of the purified graft copolymer were determined by ~1H-NMR and GPC analysis.     

过硫酸胺与N－［（3－二甲氨基）丙基］丙烯酰胺氧化还原引发体系的研究

N-[(3-DimetLylamino)-propyll acrylamide(DMAPAA) and N-[(3dimetliylamino)-propyl] methacrylamide(DMAPMA) were synthesized by the reaction of 3-dimethylamino-propylamine with acryloyl and methacryloyl chloride respectively at 0-5℃ temperature. The kinetics of the aqueous solution polylmerization of acrylamide(AAm) by using ammonium persulfate(APS) combined with DMAPAA or DMAPMA was investigated. The rate equations were given as:respectively. The overall activation energies of the polymerization were determined as low as 35.0kJ/mol and 41.0kJ/mol respectively. Based on the end-group analysis results, the reaction mechanism of DMAPAA or DMAPMA with APS was proposed to be similar to the initiation reation of persulfate/tertiary aliphatic amine redox system,and the resulting aminomethyl radicals were responsible for initiation of vinyl polymerization as well as sulfate radical.     

有机过氧化物与N-甲基-N-2-羟乙基苯胺引发体系的研究

测定了有机过氧化物与N-甲基-N-2-羟乙基苯胺(HMA)体系引发MMA聚合的动力学方程和聚合表现活化能。由过氧化物/HMA/MNP的ESR波谱证实芳叔胺HMA中,与氮原子相连的亚甲基的氢被摘去形成相应的碳自由基,它能引发单体聚合成为聚合物的端基。这也由聚合物的UV光谱所证实,由实验结果提出这类体系的引发机理。     

PHOTOSENSITIVITY OF Ce (Ⅳ) INITIATED METHYL ACRYLATE POLYMERIZATION

The influences of UV light irradiation (313 nm) and diffused daylight on the polymerization of methyl acrylate initiated by the ceric ammonium nitrate without any reducing agent have been studied both in aqueous nitric acid and in pure water. The rate of polymerization was found to be accelerated and the overall activation energy and the induction time were found to be decreased sharply by the UV light irradiation. Under UV light, the rate of polymerization is 8 times as high as the rate in dark. The rate of polymerization was found to attain a maximum with the increase of nitric acid concentration and the rate of polymerization became less sensitive to UV light in the presence of nitric acid whereas the induction period reduced outstandingly. Based on the experimental results, the mechanism is proposed.     

甲基丙烯酸2-羟乙酯水溶液聚合与硫氰化钠的效应

<正> 甲基丙烯酸2-羟乙酯(HEMA)是一带有羟基的功能性单体,它可以在自由基聚合引发剂如过氧化苯甲酰、偶氮二异丁腈、过氧化二碳酸二异丙酯或氧化还原引发体系过硫酸盐-乙酸二甲胺基乙酯的作用下进行自由基聚合,我们已报道带有羟基的单体如HEMA、甲基丙烯酸羟丙酯(HPMA)及甲基丙烯酯3-甲氧基-2-羟丙酯(MHPMA)可用     

溶胶－凝胶化学与无机/有机杂化高聚物材料的合成

溶胶－凝胶过程是合成无机固体材料的一种常用手段，但将其应用到合成聚合物新材料上则是一种新型的方法。本文介绍了溶胶－凝胶过程在合成无机／有机杂化聚合物中的应用，并讨论了采用这种方法所得到的材料的性能。     

铈离子与氨基甲酸酯类化合物引发丙烯酰胺聚合的研究

本文对铈离子与苯基氨基甲酸酯类化合物在H_2O-CH_3CN(3∶1,V/V)及H_2O-HCONH_2(1∶2,V/V)两种介质中引发丙烯酰胺的聚合进行了研究。考察了不同结构的苯基氨基甲酸酯对聚合的影响。苯基氨基甲酸酯类化合物对铈离子引发聚合均有促进作用,其中对-甲苯基氨基甲酸酯的促进作用最为显著。测定了聚合反应表现活化能及聚合动力学方程,并提出了聚合反应机理。     

甲壳胺接枝聚合反应的研究

本文是以过硫酸钾为引发剂，研究甲基丙烯酸甲酯（ＭＭＡ）与甲壳胺的接枝聚合反应．通过对不同脱乙酰度（ｄａ）甲壳胺（ＣＴＳ）的接枝聚合反应条件实验，研究了反应时间，温度，引发剂浓度和单体浓度对接枝聚合反应的影响，从中得到优选的反应条件．在相同条件下，比较不同脱乙酰度甲壳胺及Ｎ－取代甲壳胺的接枝聚合反应结果，表明：甲壳胺中氨基参与了接枝聚合反应的引发过程．