ATRP“一步法”合成支化聚苯乙烯支化发展过程

Development of Branching in the Atom Transfer Radical Copolymerization for Branched Polystyrene

以α-溴代异丁酸叔丁酯为引发剂,溴化亚铜CuBr/2,2′-联二吡啶为催化体系,双甲基丙烯酸二缩三乙二醇酯为支化单体,甲苯为溶剂,在90℃经原子转移自由基聚合反应合成支化聚苯乙烯。用气相色谱仪(GC)、核磁共振(1H-NMR)、三检测凝胶渗透色谱仪(TD-GPC)对聚合反应过程进行了分析。研究发现,反应体系内存在三种分子量和支化程度明显不同的组分:初级链、由两条初级链偶联而成的简单支化分子和三条以上初级链偶联而成的高度支化分子的混合物;随单体转化率的上升,支化分子的含量逐渐增加,线性结构减少但始终存在。

Branched polystyrene was synthesized by atom transfer radical polymerization （ATRP） using triethylene glycol dimethacrylate （tri-EGDMA） as the branching agent in toluene at 90 ℃.The copolymerization behavior and the structure of copolymers were investigated by 1H-NMR,gas chromatography （GC）,gel permeation chromatography （GPC） coupled with multi angle laser light scattering （MALLS） and an on-line viscometer.Analysis of the changes of pendant vinyl groups shows that the formation of branched chains occurs at very early stages of the reaction.The result is confirmed by GPC measurement.The reaction system consists of three components of marked different molecular weights and degrees of branching：the primary chain,the slightly branched chain containing two primary chains,and the highly branched chain containing more than three primary chains.