含溴四官能团引发剂引发单电子转移活性自由基聚合

以季戊四醇为原料合成了2,2-二溴甲基-1,3-二溴丙烷(PEBr4),并以此为引发剂,Cu0粉/三-(2-二甲氨基乙基)胺(Me6-TREN)为催化体系,在二甲亚砜(DMSO)中实现了丙烯酸甲酯(MA)的单电子转移活性自由基聚合(SET-LRP),得到了星形PMA。采用1H-NMR对PMA结构进行表征确认并采用GPC测定了PMA的分子量及分子量分布,单体转化率为36.3%时聚合物的分子量为13300,-Mw/-Mn=1.40;考察了水、单体/催化剂(引发剂)配比对聚合反应的影响。结果表明,H2O含量增加到20%(体积分数)导致表观聚合速率常数(kappp)由0.0367 h-1增加到0.2785 h-1;增加催化剂及引发剂用量分别导致kappp增加。

Single Electron Transfer Living Radical Polymerization Using 2,2-Dibromo-Methyl-1,3-Dibromo-Propane as Four Functional Initiator

The star-shaped PMA was synthesized by SET-LRP at 30 ℃ with DMSO as the solvent of polymerization,PEBr4 as the multifunctional initiator,Cu0 powder and Me6-TREN as catalytic system.The PMA prepared via SET-LRP was characterized by GPC and 1H-NMR to identify the polymerization mechanism,and the results show that polymer has the perfect functional chain ends and relatively low molecular weight distribution,indicating a controlled polymerization.The effects of water,catalyst and initiator on polymerization were studied;the results show that the H2O content in binary mixtures increases to 20%(volume fraction) led to the kappp increasing from 0.0367 h-1 to 0.2785 h-1.meanwhile the kappp increases in corresponding with increasing catalyst amount or initiator amount,in addition,the w/n of PMA decreases as the amount of H2O,catalyst and initiator increase.