具有窄分子量分布和羧基末端的聚甲基丙烯酸甲酯和聚苯乙烯的合成

Preparation of carboxyl-end-group poly(methyl methacrylate) and polystyrene with low polydispersity

以CuCl/TMEDA为催化剂、氯乙酸为引发剂利用原子转移自由基聚合方法在本体或溶液体系中合成了具有窄分子量分布和末段羧基的聚甲基丙烯酸甲酯和聚苯乙烯。在两种单体的本体或溶液聚合体系中,单体和氯乙酸的配料比增加,有利于聚合反应速度的加快;本体中进行的甲基丙烯酸甲酯和苯乙烯聚合反应速率比相应的溶液聚合体系快,但是得到的最终产物的分子量分布指数Mw/Mn较宽;溶液聚合方法的使用,使聚合反应速度缓和,得到的聚合产物聚甲基丙烯酸甲酯和聚苯乙烯的Mw/Mn介于1.17-1.21和1.16-1.19之间,具有理想的窄分子量分布;动力学实验表明,聚合反应以ATRP的聚合机理进行,体现出活性/可控聚合的特征;聚合产物聚甲基丙烯酸甲酯和聚苯乙烯及其末段端基由~1HNMR表征。

Carboxyl-end-group poly(Methyl methacrylate)(PMMA)and polystyrene(PS)with low polydispersity were successfully carried out via atom transfer radical polymerization(ATRP)in bulk or in solution with chloroacetic acid as initiator and CuCl/N,N,,N,-Tetramethylethylenediamine(TMEDA)as catalyst.The polymerizations showed the different polymerization rates depending on the feeding ratios for the ATRP of both methacrylate(MM A)and styrene(St)in either bulk or solution polymerization.The bulk polymerization for both monomers MMA and St gave a faster polymerization rate and afforded a broader Mw/Mn of the obtained pol-ymer.When the solvent was added into the polymerization system,the polymerization showed a moderate rate and yielded PMMA with the narrowest Mw/Mn of1.17-1.21and PS with the narrowest Mw/Mn of1.16-1.19,respectively.Polymerization kinetics showed that the polymerization proceeded by the normal ATRP.The end groups of the well-defined PMMA and PS were determined by!HNMR.