苯乙烯的低温原子转移自由基聚合:扩散效应导致的加速现象  

Low-Temperature Atom Transfer Radical Polymerization of Styrene:Diffusion-induced Acceleration

作　　者：方艳[1] 翟光群[1] 蒋必彪[1] 陈建海[1] 

机构地区：[1]常州大学材料科学与工程系,常州213164

出　　处：《化学学报》2011年第7期853-862,共10页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20674033);江苏省自然科学基金(No.BK2008142)资助项目

摘　　要：研究了以苯乙烯(St)和N-[4-(2-溴丙酰氧基)苯基]马来酰亚胺(BPPM)的交替共聚物P(St-alt-BPPM)为大分子多官能度引发剂,以CuBr/2,2'-联吡啶(bpy)为催化体系,环己酮为溶剂,在60或80℃下进行St的原子转移自由基聚合(ATRP).结果表明,反应呈现活性聚合的假一级反应动力学特征,聚合物分子量随着单体转化率上升而增加,降低反应温度将减低反应速率,但是所得聚合物[P(St-alt-BPPM)-g-PS]分子量分布更窄.水解实验证明该过程具有一定可控性.由于类似的单官能度引发剂无法在同等条件下顺利引发St的ATRP,因此采用大分子多官能度引发剂可以大幅度降低ATRP的反应温度.此加速现象被归因于CuBr/bpy从大分子引发剂线团外向线团内扩散,而CuBr2/bpy则从大分子引发剂线团内向线团外扩散,从而提高大分子引发剂线团中的自由基浓度和聚合反应速率.The CuBr/2,2＇-bipyridine （bpy）-catalyzed atom transfer radical polymerization （ATRP） of styrene （St） initiated by well-defined poly（styrene-alt-N-[4-（a-bromopropyloxy）phenyl]maleimide） [P（St-alt-BPPM）] in cyclohexanone at 60 and 80℃ was investigated. The results showed that the reaction appeared to follow pseudo-first order kinetics, and the molecular weight （Mw） of the polymer P（St-alt-BPPM）-g-PS increased with the monomer conversion. A lower reaction temperature would reduce the reaction rate and lead to a narrower molecular weight distribution of the P（St-alt-BPPM）-g-PS. The Mw data of the PS side chains confirmed that the process was in a controlled fashion. The ATRP of St cannot be successfully initiated by low-Mw analogue under similar conditions, so using multi-functional macroinitiator would significantly reduce the reaction temperature. Such an acceleration effect was attributed to the diffusion of CuBr/bpy from the macro-initiator coil outside to inside and that of CuBr2/bpy from inside to outside, resulting in an enhanced concentration of propagating radicals inside the coil and an faster polymerization rate.

关 键 词：苯乙烯 原子转移自由基聚合 大分子多官能度引发剂 扩散效应 加速 

分 类 号：O631.5[理学—高分子化学]