高分子量立构复合结晶的三枝化PPO-PDLA-PLLA 嵌段共聚物

摘要

Three-arm poly(propylene oxide) (PPO) was used as a macroinitiator for the ring-opening poly-merization(ROP) of D-lactide to obtain three-arm poly( propylene oxide)-block-poly(D-lactic acid) ( PPO-PDLA). PPO-PDLA copolymer was then reacted with stannous octoate [Sn(Oct) 2 ] to obtain Sn(Oct) end-capped PPO-PDLA[PPO-PDLA-Sn(Oct)]. The PPO-PDLA-Sn(Oct) can be used as an efficient macroinitia-tor for the ROP of L-lactide to synthesize three-arm PPO-PDLA-PLLA at 130 ℃, which reduces the occurrence of hydrolysis and transesterification reaction. PPO-PDLA-PLLA copolymers with high molecular weight were synthesized by this novel and simple method. The results show that the composite of PPO-PDLA-PLLA can be easily tuned by controlling the feed ratio of L-lactide and D-lactide, and the stereoregularity of PPO-PDLA-PLLA is high. Moreover, the stereocomplexes of PPO-PDLA-PLLA can survive melting to reform the stereo-complex crystallites.%以三枝化低不饱和度聚环氧丙烷(PPO)引发 D-丙交酯(D-LA)逐步开环聚合，合成了三枝化聚环氧丙烷-聚右旋乳酸(PPO-PDLA)共聚物。用辛酸亚锡 Sn(Oct)2与 PPO-PDLA 端羟基反应进行 Sn(Oct)封端，制备了三枝化 PPO-PDLA-Sn(Oct)预聚物。再于130℃下，以其作为大分子引发剂与 L-丙交酯(L-LA)开环聚合，合成了分子量>105的三枝化 PPO-PDLA-PLLA 嵌段共聚物。活性端基的引入，降低了聚合反应温度，从而降低了聚合中的酯交换或热降解反应发生的概率。实现了高分子量 PPO-PDLA-PLLA 嵌段共聚物的合成。结构测试结果表明，合成的嵌段共聚物具有分子结构易控及立构规整度高等特点。在结晶-熔融-再结晶重复热处理下，三枝化 PPO-PDLA-PLLA 嵌段共聚物仅发生立构复合聚乳酸结晶，且结晶能力稳定。