双马来酰亚胺为支化单体合成支化聚苯乙烯

Preparation of Branched Polystyrene Using Bismaleimide as the Branch Agent

以六次甲基双马来酰亚胺(BMIH)为支化单体,α-溴代异丁酸叔丁酯(t-BBiB)为引发剂,CuBr/N,N,N′,N″,N″-五甲基二亚乙基三胺(PMDETA)为催化体系,苯甲醚为溶剂,在80℃下经原子转移自由基聚合(ATRP)合成支化聚苯乙烯。用气相色谱(GC),三检测凝胶渗透色谱(TD-GPC)和核磁(1 H NMR)等测试方法对反应过程,聚合物结构以及残留初级链进行分析和表征。研究结果表明:因为苯乙烯和双马来酰亚胺之间存在电子转移络合物效应,所以BMIH在反应早期很快消耗。但是由于位阻效应使得悬垂双键表现出相对较为平缓的转化率,而不是在反应初期就很快参加聚合,因此得到无规支化聚合物,而非真正意义上的星状聚合物。支化聚合物分子质量分布较宽是因为体系中残留不含悬垂双键的初级链。

The preparation of branched polystyrene using bismaleimide as the branch agent was studied via atom transfer radical polymerization （ATRP）. Gas Chromatography （GC）, three detection gel permeation chromatography （TD--GPC） and proton nuclear magnetic resonance （1H NMR） were used to clarify the polymerization process and the resulting polymers. GC and NMR analyses show that BMIH converts in the initial stage of the reaction due to the effect of the change transfer complex between styrene and maleimide. The pendent vinyl group, however, participates in polymerition gradually because of the steric effect in the polymeritation system. Hence, random branched polystyrene rather than star polystyrene has resulted. The limited content of the pendent vinyl group gives rise to the residue of the primary chain, which results in much wider molecular weight distribution of the final branched polystyrene.