Xie Rui, Wang Yuhui, Li Shuai, Li Bo, Xu Jie, Liu Jinqian, He Yuchen, Yang Guan-Wen, Wu Guang-Peng
MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, P. R. China.
College of Material Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, 311121, Zhejiang, P. R. China.
Angew Chem Int Ed Engl. 2024 Jul 1;63(27):e202404207. doi: 10.1002/anie.202404207. Epub 2024 May 27.
Alkyl borane compounds-mediated polymerizations have expanded to Lewis pair polymerization, free radical polymerization, ionic ring-opening polymerization, and polyhomologation. The bifunctional organoborane catalysts that contain the Lewis acid and ammonium or phosphonium salt in one molecule have demonstrated superior catalytic performance for ring-opening polymerization of epoxides and ring-opening copolymerization of epoxides and CO than their two-component analogues, i.e., the blend of organoborane and ammonium or phosphonium salt. To explore the origin of the differences of the one-component and two-component organoborane catalysts, here we conducted a systematic investigation on the catalytic performances of these two kinds of organoborane catalysts via terpolymerization of epoxide, carbon dioxide and anhydride. The resultant terpolymers produced independently by bifunctional and binary organoborane catalyst exhibited distinct microstructures, where a series of gradient polyester-polycarbonate terpolymers with varying polyester content were afforded using the bifunctional catalyst, while tapering diblock terpolymers were obtained using the binary system. The bifunctional catalyst enhances the competitiveness of CO insertion than anhydride, which leads to the premature incorporation of CO into the polymer chains and ultimately results in the formation of gradient terpolymers. DFT calculations revealed the role of electrostatic interaction and charge distribution caused by intramolecular synergistic effect for bifunctional organoborane catalyst.
烷基硼烷化合物介导的聚合反应已扩展到路易斯对聚合、自由基聚合、离子开环聚合和多同系化反应。在一个分子中同时含有路易斯酸和铵盐或鏻盐的双功能有机硼烷催化剂，相较于其两组分类似物（即有机硼烷与铵盐或鏻盐的混合物），在环氧化物的开环聚合以及环氧化物与二氧化碳的开环共聚反应中展现出了卓越的催化性能。为探究单组分和双组分有机硼烷催化剂差异的根源，在此我们通过环氧化物、二氧化碳和酸酐的三元共聚反应，对这两种有机硼烷催化剂的催化性能进行了系统研究。由双功能和二元有机硼烷催化剂分别制备的三元共聚物呈现出截然不同的微观结构，其中使用双功能催化剂可得到一系列聚酯含量各异的梯度聚酯 - 聚碳酸酯三元共聚物，而使用二元体系则可获得渐变二嵌段共聚物。双功能催化剂增强了二氧化碳插入相较于酸酐的竞争力，这导致二氧化碳过早地插入到聚合物链中，最终形成梯度三元共聚物。密度泛函理论计算揭示了双功能有机硼烷催化剂分子内协同效应所引发的静电相互作用和电荷分布的作用。
