聚乳酸是可生物降解高分子材料最重要的一类代表,但其自身存在脆性、降解不可控、功能单一等不足。通过共聚改性可丰富此类聚合物链结构，然而共聚单体聚合反应速率差异较大，聚合物链结构难以有效调节进而改善材料性能。如何实现此类共聚物微观结构的有效调控，是目前面临的关键问题。本项目拟将金属有机催化剂对手性丙交酯优异的立构控制能力拓展到手性/非手性单体共聚合及序列调控领域：设计侧臂具有不同空间/电子效应的一系列高杂同稀土金属有机催化剂，利用催化剂和手性单体协同产生的链端控制效应增大非手性单体的插入率，进一步通过催化剂侧臂的改变调节共聚单体的相对反应速率，实现共聚物序列结构的有效调控；研究不同结构手性/非手性单体适用范围，完善聚合物序列调控规律；发展功能化非手性单体及特色单体，结合调控规律制备新型功能高分子及可控降解新材料。本项目将为序列可控开环聚合提供新方法，为共聚改性及开发功能材料提供新手段。

As a representational biodegradable polymer materials, polylactic acid (PLA) has been obtained a great attention and development. The deficiency of uncontrolled-degradation, poor hydrophilic property, uncomplicated function，etc. need to be improved by copolymerization method. However, as the different reactivity ratios of two comonomers, the achievement of the sequence-regulated polymerization with precise microstructure of polymer chain is crucial for resolving these problems. This program will share an advantages of high stereo-controlled capability originated by metal catalyst to a chiral/achiral monomers copolymerization and their sequence controlled research. A series of rare-earth metal based catalysts with various substituents on side arm together with a different structural cyclic esters will be designed and synthesized. Taking advantage of high chain-end control effect arising from the synergy between catalyst and chiral monomer, the related reactivity ratio of chiral and achiral comonomers will be controlled by the steric/electric effects of substituents on catalyst. The match of different structural comonomers will be researched and the effectual role for instructing the sequence controlled copolymerization will be established. The functional achiral monomers and distinctive monomers will be developed for building functional polymers or controlled-degradation materials, by means of the sequence controlled polymerization role. This project will provide a new method for sequence controlled ring-opening polymerization and present a solution for modified copolymerization and developed new materials.