胺基桥联双芳氧基稀土金属催化剂催化丙交酯与环酯类单体无规共聚的研究

Random co-polymerization of lactide and other cyclic esters such as ε-caprolactone combines the advantages of respective homopolymers, and is an efficient strategy to prepare polymers with superior properties. Due to the different reactivity ratio between lactide and other cyclic esters (the polymerization of lactide is apparently faster than that of ε-caprolactone during co-polymerization), current catalysts showed limited abilities in catalyzing the random co-polymerization of lactide and other cyclic esters. Thus, development of new and efficient catalyst is the key issue to solve these problems..On the basis of our previous studies, a series of rare earth metal complexes stabilized by amine-bridged bis(phenolato) ligands with confirmed structures will be designed and synthesized, and their catalytic activities in catalyzing the “one-pot” co-polymerization of lactide and ε-caprolactone, as well as cyclic carbonates, will be investigated and compared in this project. The relationship between the structures of these rare earth metal catalysts and their catalytic performance for the co-polymerization of lactide and other cyclic esters will be systematically studied. It is expected that the random co-polymerization of lactide and ε-caprolactone catalyzed by rare earth metal catalyst will be achieved. Based on these results, 2-3 novel and highly efficient rare earth metal catalystes, which can catalyze the “one-pot” random co-polymerization of lactide and ε-caprolactoneas as well as other cyclic esters, will be developed. The mechanisms of these “one-pot” random co-polymerizations catalyzed by rare earth metal catalysts will be examined, which will provide guidelines on preparing new rare earth metal catalystes that are active in catalyzing the “one-pot” random co-polymerization of lactide and other cyclic esters. 16 publications in SCI-indexed journals and 4 Chinese patents are expected to be published supported by this project.

丙交酯和ε-己内酯等环酯类单体的无规共聚物可以最大限度地结合聚丙交酯和聚ε-己内酯等均聚物的各自优点，得到性能更优异的高分子材料。由于丙交酯与其它环酯在共聚性能上的差异，现有的催化剂难以高效催化丙交酯与它们的无规共聚。因此，发展新的高效催化剂是解决问题的关键。.本项目在已有工作的基础上，设计合成一系列具有特定结构的胺基桥联双芳氧基稀土金属催化剂，系统研究这些催化剂的结构与其催化丙交酯与不同环酯 “一锅”共聚性能之间的关系，利用稀土金属催化剂实现丙交酯和ε-己内酯的无规共聚；在此基础上，开发2～3个具有自主知识产权的、能高效催化丙交酯与环酯类单体“一锅”无规共聚的新型稀土金属催化剂；研究稀土金属催化剂催化丙交酯与不同环酯 “一锅”无规共聚的机理，为进一步设计合成新的、能够高效催化这些单体无规共聚的稀土金属催化剂提供理论指导。发表SCI源期刊论文16篇左右，申请中国发明专利4项左右。

丙交酯和ε-己内酯等环酯类单体的无规共聚是得到性能更优异的高分子材料有效方法。但是，由于不同单体共聚性能的差异，现有的催化剂难以实现丙交酯与其它环酯的无规共聚，需要发展新的高效催化剂。.四年来，本课题按照项目计划书的要求，设计合成了以N,N-二甲胺基-胺基桥联双芳氧基、乙二胺基桥联双芳氧基和亚乙基三胺桥联席夫碱等为辅助配体的具有不同配位环境的稀土金属配合物，表征了其中50多个配合物的结构。系统研究这些催化剂催化丙交酯与ε-己内酯和外消旋-丁内酯等环酯共聚的性能，重点研究了催化剂的空间位阻和电子效应等因素对催化剂的催化性能及所得聚合物的链结构的影响规律。首次发现稀土金属催化剂在一定的条件下可以催化丙交酯与ε-己内酯的“一锅”共聚，得到无规共聚物；并进一步阐明了该无规共聚物的生成是由于聚合过程中的酯交换反应实现的；通过对催化剂结构的筛选，首次实现了在常温下丙交酯与ε-己内酯的“一锅”无规共聚。在此基础上，通过进一步研究，第一次实现了聚丙交酯与ε-己内酯的“一锅”无规共聚，这不仅为制备丙交酯和己内酯的无规共聚物提供了新的方法，而且为聚丙交酯材料的改性提供了一种直接、方便的方法，为制备基于聚丙交酯的无规共聚物提供了新的思路。针对目前文献很少涉及丙交酯与外消旋-丁内酯的共聚的现状，我们比较系统地研究了稀土金属催化剂催化这两种单体共聚的性能，特别是对所得共聚物的链结构进行详细的分析，为今后研究这两种单体的共聚奠定了基础；并且通过选择不同离子半径的稀土金属催化剂，第一次实现了丙交酯与外消旋-丁内酯从梯度共聚到无规共聚的调控。首次发现辅助配体的电子效应对外消旋-丁内酯均聚的立体选择性有显著的影响，这为今后设计合成高效、高选择性金属催化剂提供了新的思路。此外，发现部分稀土金属配合物可以在相对温和的条件下催化L-lacOCA的开环聚合反应等。四年来，发表标注的SCI源期刊论文24篇，获得授权中国发明专利5项。完成了预期的研究计划。

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