丙烯酸丁酯细乳液单电子转移-蜕化链转移聚合反应

单电子转移-蜕化链转移(SET-DT)聚合是一种单体适用性广、对聚合环境要求不苛刻的活性自由基聚合方法。以Na_2S_2O_4为催化剂,CHI3为引发剂,采用水相细乳液聚合法进行丙烯酸丁酯(BA)的SET-DT活性自由基聚合,考察了聚合温度、引发剂/催化剂浓度、催化剂滴加方式和乳化剂浓度对聚合动力学、聚丙烯酸丁酯(PBA)数均分子量和分子量分布的影响。结果表明,细乳液聚合速率明显大于悬浮聚合,可在较低温度(30℃以下)、较低引发剂和催化剂浓度(BA,CHI_3和Na_2S_2O_4的初始摩尔浓度比为1 600:1:8)下实现BA的快速聚合;通过聚合过程滴加Na_2S_2O_4催化剂和增加十二烷基硫酸钠主乳化剂浓度,可提高聚合速率;采用低引发剂浓度和催化剂逐步滴加聚合得到的PBA的平均分子量较大,分子量分布较窄。

Miniemulsion Single Electron Transfer-Degenerative Chain Transfer Polymerization of Butyl Acrylate

Single Electron Transfer-Degenerative Chain Transfer (SET-DT) polymerization is a living radical polymerization (LRP) process exhibited wide monomer applicability under mild reaction conditions.In this paper, SET-DT LRP of butyl acrylate(BA) catalyzed by Na2S2O4and initiated by CHI3 in aqueous phase were carried out in a miniemulsion way. The influences of polymerization temperature, initiator/catalyst concentrations, catalyst adding policy and emulsifier concentration on the polymerization kinetics, number average molecular weight (Mn) and polydispersity index (PDI) of poly(butyl acrylate) were investigated. It was found that BA SET-DT miniemulsion polymerization exhibited much greater polymerization rate than that of suspension polymerization at the same polymerization temperature and catalyst/initiator concentrations. BA can be rapidly polymerized at lower temperature (below 30℃), and lower initiator/catalyst concentrations (the initial molar ratio of BA, Na2S2O4 to CHI31600:1:8). The polymerization rates were increased by adding Na2S2O4 continuously, reducing the monomer droplet (latex particle) size and increasing the concentration of sodium dodecyl sulfate emulsifier during the polymerization. Poly(butyl acrylate) prepared at lower initiator concentration and with continuous addition of catalyst exhibited graterMn and lowerPDI.