RAFT聚合法研究丙烯酸酯自由基聚合链间转移过程  

Feasible Method for the Determination of the Chain Transfer Constants of Acrylates to Polymers in Free Radical Polymerization via RAFT Polymerization

作　　者：郭睿威[1] 张梦媛 薛杨 张世先 Guo Ruiwei;Zhang Mengyuan;Xue Yang;Zhang Shixian(School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学化工学院,天津300072

出　　处：《天津大学学报（自然科学与工程技术版）》2021年第7期687-693,共7页Journal of Tianjin University：Science and Technology

摘　　要：针对丙烯酸酯自由基聚合过程中链间转移常数测定难题,提出了新的测试策略,即在低分子量聚丙烯酸酯存在下,以UV标记的RAFT试剂N-咔唑二硫代甲酸苄基酯(BCBD)调控第二单体进行RAFT聚合,聚合产物经梯度淋洗聚合物色谱(GPEC)分离,直接测定由向聚合物转移所产生嵌段物的相对摩尔比,并以此估算增长链自由基向另一种聚合物的链转移常数.然后以异丙醇为链转移剂制得的低分子量聚丙烯酸甲酯(iPr-PMA)、丙烯酸乙酯(EA)为例,在优化GPEC分离条件后,选用二氯乙烷/甲醇为淋洗剂实现了RAFT聚合的均聚物RPEA与链转移生成的嵌段物iPr-PMA-b-RPEA的有效分离,测得了80℃、100℃和120℃下PEA增长链向iPr-PMA的转移常数.结果表明,这一过程的链转移常数在10-4数量级,且随温度升高而增大;通过RAFT聚合与GPEC技术相结合,可以高效简易地测定自由基聚合中向聚合物的链转移常数,而不必依赖其他动力学参数.这一方法的建立为深入研究链间转移动力学及影响因素提供了可行的方法.A new measuring strategy was proposed to determine the interchain transfer constant during the free radical polymerization of acrylates.An acrylate monomer was subjected to RAFT polymerization controlled with a UVlabeled RAFT agent,namely,benzyl N-carbazole dithiocarboxylate,in the presence of another pre-prepared lowmolecular-weight polyacrylate.The RAFT polymerization products were separated through gradient polymer elution chromatography(GPEC),and the relative molar content of the blocked product formed via the transfer of the polyacrylate radical to the pre-prepared polyacrylate was directly determined.The chain transfer constant of the growing chain radical in the polymer was estimated.As an example,ethyl acrylate(EA)was selected as the monomer,and polymethyl acrylate(iPr-PMA)prepared in isopropyl alcohol was chosen as the pre-prepared polymer matrix.The GPEC separation conditions were optimized,and a dichloroethane/methanol mixture was used as the eluent that could effectively separate the homopolymer RPEA and the block iPr-PMA-b-RPEA generated via the chain transfer to iPr-PMA.The chain transfer constants of the PEA growth radicals to iPr-PMA at 80℃,100℃,and 120℃were estimated.Results showed that the chain transfer constants were in the order of 10-4,and they increased with the increase of temperature.The chain transfer constant of the polymer in free radical polymerization could be efficiently and simply measured through the combination of RAFT polymerization and polymer liquid chromatography technology without relying on other kinetic parameters.This method was demonstrated to be feasible for studying the interchain transfer dynamics and influencing factors.

关 键 词：丙烯酸酯 向聚合物的链转移 RAFT聚合 梯度淋洗聚合物色谱 

分 类 号：TK448.21[动力工程及工程热物理—动力机械及工程]