郭睿威,张梦媛,薛 杨,张世先
AuthorsHTML:郭睿威，张梦媛，薛 杨，张世先
AuthorsListE:GuoRuiwei,Zhang Mengyuan,Xue Yang,Zhang Shixian
AuthorsHTMLE:GuoRuiwei，Zhang Mengyuan，Xue Yang，Zhang Shixian
Unit:天津大学化工学院，天津 300072
Unit_EngLish:School of Chemical Engineering and Technology，Tianjin University，Tianjin 300072，China
Abstract_Chinese: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．
Abstract_English: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 UV-abeled RAFT agent，namely，benzyl N-carbazole dithiocarboxylate，in the presence of another pre-prepared low molecular-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.
Keyword_Chinese:丙烯酸酯；向聚合物的链转移；RAFT 聚合；梯度淋洗聚合物色谱
Keywords_English:acrylate；chain transfer to polymer；RAFT polymerization；gradient polymer elution chromatography

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