中文摘要：

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〉10^5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．在结晶一熔融一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．

英文摘要：

Three-arm poly （propylene oxide） （PPO） was used as a macroinitiator for the ring-opening polymerization（ROP） of D-lactide to obtain three-arm poly （propylene oxide）-block-poly （D-lactic acid）（ PPO- PDLA）. PPO-PDLA eopolymer 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 macroinitiator 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 stereocomplex crystallites.