Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization (ROP) of lactones, including δ-valerolactone, ε-caprolactone, and δ-hexalactone. The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a (thio)urea at elevated temperature under vacuum, and used in cooperation with an alcoholic initiator. The performance of the catalyst is readily adjusted and optimized through variation of the (thio)urea precursor, catalyst composition, and reaction condition. Urea-derived catalysts are generally superior to thiourea-derived ones. Provided with proper N-substituents, the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification, even at high monomer conversion and/or substantially extended reaction time. In addition to acidity, structural symmetry of the urea also proves decisive for the catalytic activity, which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.

开发了一种高效的离子有机催化剂，用于室温控制的内酯开环聚合（ROP），包括δ-戊内酯，ε-己内酯和δ-六内酯。通过在升高的温度和真空下简单地混合氢氧化四正丁基铵和（硫）脲来制备催化剂，并与醇类引发剂配合使用。通过改变（硫代）脲前体，催化剂组成和反应条件，可以容易地调节和优化催化剂的性能。脲衍生的催化剂通常优于硫脲衍生的催化剂。提供适当的N取代基，即使在高单体转化率和/或基本上延长的反应时间下，该催化剂也能在大分子酯交换反应中提供高聚合效率和高单体选择性。除酸度外，尿素的结构对称性也证明对催化活性起决定性作用，这使内酯开环的催化剂辅助质子转移过程成为可能，从而为氢键型双官能团催化的ROP提供了新颖的机理见解。离子有机催化剂。