环酯活性开环(共)聚合反应研究与结构明确的多嵌段共聚物合成

Polylactide (PLA), a representative of aliphatic polyester, is an important class of environmentally friendly polymer. This project focuses on design and synthesis aluminium, zinc, and magnesium catalysts bearing Schiff bases to realize highly efficient ring-opening polymerization (ROP) of aliphatic cyclic ester. By changing the structural model of catalysts as well as modifying the electronic effect and steric hindrance of Schiff base ligand, polymers with high molecular weight and narrow molecular weight distribution can be obtained through depressing side reactions, such as depolymerization and transesterification. To enhance the heat-resistant property and operating temperature of PLA, a synthetic method of well-defined multiblock copolymers of D-lactide and L-lactide with high molecular weight will be established to prepare PLA stereocomplex, by using novel organometallics and Lewis Acid-base Pair catalysts. Meanwhile, a new method will be also developed to synthesize well-defined high-molecular-weight multiblock copolymers of cyclic diester/lactone and cyclic diester/cyclic carbonates, etc. To tune the biodegradability of aliphatic polyester, a new synthetic method of random and gradient copolymers of esters with high molecular weight will be established, by using novel organometallics and Lewis Acid-base Pair catalysts without side reactions of depolymerization and transesterification.

聚丙交酯为代表的脂肪族聚酯是一类重要的环境友好高分子材料。本项目以脂肪族环酯的高效活性开环聚合反应为研究对象，设计合成新型希夫碱铝、锌、镁催化剂，改变催化剂结构模式和调节希夫碱配体的电子效应与空间位阻，抑制聚合物解聚和酯交换等副反应，制备高分子量、窄分布聚合物。以提高聚丙交酯耐热等级和使用温度等为目标，利用新型有机金属和Lewis Acid-base Pair催化剂，建立结构明确的D-丙交酯和L-丙交酯的高分子量多嵌段共聚物的合成方法，制备结构比较完善的聚丙交酯立体复合物；发展合成结构明确的高分子量交酯/内酯和交酯/环碳酸酯等多嵌段共聚的合成新方法。以调节脂肪族聚酯材料的生物降解特性为目标，利用不存在酯交换和解聚副反应的新型高效有机金属催化剂和Lewis Acid-base Pair催化剂，建立高分子量无规共聚酯和梯度共聚酯的合成新方法。

脂肪族聚酯作为绿色、环境友好型的生物可降解材料，受到了学术界和工业界的广泛的关注。本项目以减小聚酯分子链中羰基与活性中心发生配位反应倾向、抑制酯交换等副反应为目标，从改变有机金属催化剂的配位模式、调节金属中心原子的电核密度和空间位阻入手，设计并优化了新型高效环酯活性开环聚合反应铝、镁催化剂。通过多种表征手段并结合理论计算模拟，系统、深入地研究了ZnR2/有机碱Lewis Pairs 体系催化环酯开环聚合的机理并将Lewis Pairs催化体系拓展到环酐/环氧化合物的交替共聚反应中，实现了环酐/环氧化合物高区域选择性和化学选择性共聚合反应；实现了丙交酯/环酐-环氧多组份体系的“自切换”聚合，发展了“一锅法”合成结构明确的高分子量丙交酯/环酐-环氧多嵌段共聚酯的新方法。