Geng Xiaowei, Liu Xiong, Yu Qinglei, Zhang Chengjian, Zhang Xinghong
State Key Laboratory of Biobased Transportation Fuel Technology, International Research Center for X Polymers, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
J Am Chem Soc. 2024 Sep 18;146(37):25852-25859. doi: 10.1021/jacs.4c09394. Epub 2024 Sep 3.
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, 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.
内酯的有机催化开环聚合（ROP）是一种制备可再生和可生物降解聚酯的绿色方法。开发具有高活性和可控性的新型有机催化剂是该领域一个重要且具有挑战性的研究课题。在此，我们报道了一系列能够实现内酯快速且可控ROP的有机催化剂。这些催化剂将（硫）脲和醇盐结合在一个分子中，并在ROP中充当引发剂。计算研究表明，此类催化剂能够实现引发剂/链端的有效分子内活化，与现有的（硫）脲/醇盐二元体系相比，具有更高的活性和更低的（硫）脲负载量。这些有机催化剂表现出与金属配合物相当的超高活性，即周转数高达900，频率高达4860 min⁻¹，可得到具有定制结构、预测分子量、窄分散度、较少差向异构化和最小酯交换反应的聚酯。催化剂的合成简单且可扩展，能够广泛调节ROP的活性。
