The unprecedented use of chain-scission reaction to constitute a facile and one-pot approach for the preparation of multiblock copolymers consisting of poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) from high molecular weight PLA was demonstrated. This involves two consecutive steps including melt transesterification (1) of PLA with PEG catalyzed by nontoxic titanium-based catalyst in an internal mixer to form short-chain block copolymers, followed by chain extension (2) using hexamethylene diisocyanate (HDI) to obtain long-chain multiblock copolymer products. Due to the primary concern on the counterbalance between chain-scission and exchange reactions, the effects of catalyst and antioxidant loadings were investigated. Excessive addition of the catalyst beyond optimal point not only deteriorated the formation of desirable products in step 1 (due to accelerated thermal degradation of PEG), but also posed detrimental effects on the efficacy of the chain extension in step 2 and mechanical properties of the final products. When appropriate amount of catalyst (0.75 phr) was used in combination with antioxidant, the long-chain copolymers exhibited extraordinarily high ductility with strain-to-break values exceeding 500%.

已证明空前使用断链反应来构成从高分子量PLA制备由聚乳酸（PLA）和聚乙二醇（PEG）组成的多嵌段共聚物的简便，一锅法。这涉及两个连续的步骤，包括在内部混合器中用无毒的钛基催化剂催化的PLA与PEG的熔融酯交换反应（1），形成短链嵌段共聚物，然后进行扩链（2）。），使用六亚甲基二异氰酸酯（HDI）获得长链多嵌段共聚物产品。由于主要关注断链和交换反应之间的平衡，因此研究了催化剂和抗氧化剂负载量的影响。催化剂的过量添加超过最佳点，不仅恶化了步骤1中所需产物的形成（由于PEG的加速热降解），而且还对步骤2中链增长的效率和最终产物的机械性能产生了不利影响。产品。当将适量的催化剂（0.75 phr）与抗氧化剂结合使用时，长链共聚物表现出极高的延展性，应变断裂值超过500％。