新型钛、锆和铪络合物的合成及立体可控催化丙交酯开环聚合研究

Public concern was directed to waste problems caused by polyolefin materials and their impact on the global environment. Development of biocompatible, degradable polylactides derived from renewable resources will relieve the increasingly serious environmental problem by waste plastics. The ring-opening polymerization (ROP) of lactide catalyzed by various metal complexes is considered as the most convenient method for preparation of high molecular weight polylactides. It is important to develop metal complexes with high stability, selectivity and activity for theoretical research and industrial application of degradable polylactides. In order to further explore structures of corresponding metal complexes and polymerization characteristics about catalyzing rac-lactide,a series of monmetric titanium, zirconium and hafnium complexes containing the tetradentate non-symmetric phenolate ancillary ligand will be synthesized and systematic research on their catalytic performance on ROP of rac-lactide will be carried out. The implementation of this proposal will reveal the relationship of structures and catalytic behavior in controlled stereoselective ring-opening polymerization and provide the theoretical and experimental support for the isoselective ROP of lactide catalyzed by titanium, zirconium and hafnium complexes.

自然界难以降解的废弃聚烯烃塑料制品对环境造成严重污染。发展生物相容、可降解且基于可再生资源的聚丙交酯高分子材料对缓解日益严重的环境问题具有重要意义。通过金属有机络合物催化丙交酯进行立构可控开环聚合，是得到高分子量聚丙交酯最有效的方法。开发高稳定性、高选择性及高活性的金属有机催化剂，无论对聚丙交酯的理论研究还是工业应用都具有重要意义。本项目预设计合成非对称双阴离子四齿桥联酚类配体，进一步合成高活性、高选择性，尤其是等规选择性的新型钛、锆和铪络合物催化剂，并对其在丙交酯立构可控开环聚合中的催化性能进行系统研究。本项目的实施将揭示催化剂在丙交酯开环聚合反应中的构效关系，为实现钛、锆和铪金属有机络合物催化丙交酯立体选择性聚合，特别是等规聚合提供理论和实验依据。

自然界难以降解的废弃聚烯烃塑料制品对环境造成了严重污染。发展生物相容、可降解且基于可再生资源的聚丙交酯高分子材料对缓解日益严重的环境问题具有重要意义。通过金属有机络合物催化丙交酯进行立构可控开环聚合，是得到高分子量聚丙交酯最有效的方法。开发高稳定性、高选择性及高活性的金属有机催化剂，无论对聚丙交酯的理论研究还是工业应用都具有重要意义。本项目合成了双异丙氧基双酚氧基氨基钛金属络合物Ti（1-5）、含有吗啉基双酚氧基类单配体钛络合物Ti(6-7)以及双配体锆络合物Zr(6-7)，所以络合物都通过了核磁共振分析以及元素分析确定其结构。络合物Ti（1-7）and Zr(6-7)在110-160 oC的条件下催化丙交酯开环聚合均有较好催化活性。其中锆络合物Zr(6-7)在熔融聚合条件下表现了“不死聚合”的特点。单体与催化剂比例高达200 000/1而聚合仍然能顺利进行，这是目前有效催化单体比例最高的催化剂。TOF值达到6592.71 h1，甚至在空气中聚合仍然能顺利进行。另外，在聚合过程中得到了较高分子量且分子量分布较窄。毫无疑问，发现高效、无毒、多功能且不贵的催化剂对绿色化学工业的发展起到举足轻重的作用。