化学
有机催化
分子内力
聚合
链条(单位)
链式转移
戒指(化学)
高分子化学
活性聚合
开环聚合
组合化学
催化作用
立体化学
有机化学
自由基聚合
对映选择合成
聚合物
天文
物理
作者
Xiaowei Geng,Xiong Liu,Qìng Yu,Chengjian Zhang,Xinghong Zhang
摘要
Organocatalytic ring-opening polymerization (ROP) of lactones is a green method for accessing renewable and biodegradable polyesters. Developing new organocatalysts with high activity and controllability is a major and challenging research topic in this field. Here, we report a series of organocatalysts to achieve a fast and controlled ROP of lactones. These catalysts incorporate (thio)urea and alkoxide in one molecule and act as initiators in the ROP. Such catalysts enable an effective intramolecular activation of initiator/chain end, as revealed by computational studies, resulting in higher activity and fewer (thio)urea loads than existing (thio)urea/alkoxide binary systems. These organocatalysts exhibit ultrahigh activity comparable to metal complexes, i.e., turnover number up to 900 and turnover of frequency up to 4860 min–1, affording polyesters with tailor-made structure, predicted molecular weights, narrow dispersity, less epimerization, and minimal transesterification. The catalyst synthesis is simple and scalable, allowing widely tuned activities of the ROP.
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