Abstract Different from traditional small molecular plasticizers, poly( l -lactic acid) (PLLA)-polyethylene glycol (PEG)-PLLA triblock copolymers were synthesized by ring-opening polymerization of L-lactide on the end hydroxyls of PEG and blended with PLLA, to enhance the crystallization of PLLA. Non-isothermal and isothermal crystallization studies show that the triblock copolymer enhances the crystallization of PLLA due to the nucleation effect from PLLA segments and the plasticization effect from PEG segments, which strongly depends on the structure of copolymers. With shorter PLLA segment and longer PEG segment of the triblock copolymer, the glass transition temperature and cold crystallization temperature of the blends decrease, and the degree of crystallinity and spherulite growth rate increase owing to the higher content of PEG. However, triblock copolymers with relatively longer PLLA segment and shorter PEG segment show unique nucleation effects for PLLA, leading to the elevation of crystallization temperature of PLLA. The results confirm that the crystallization acceleration of PLLA can be ascribed to the nucleation and plasticization effect, and the plasticization effect is more significant. What’s more, the introduction of triblock copolymers improves the compatibility and durability due to the good interfacial interaction with PLLA matrix even at a high loading.

中文翻译：

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聚（l-乳酸）-聚乙二醇-聚（l-乳酸）三嵌段共聚物：一种增强聚（l-乳酸）结晶的新型高分子增塑剂

摘要 与传统的小分子增塑剂不同，聚（l-乳酸）（PLLA）-聚乙二醇（PEG）-PLLA三嵌段共聚物是通过L-丙交酯在PEG末端羟基上开环聚合并与PLLA共混而合成的，促进PLLA的结晶。非等温和等温结晶研究表明，由于 PLLA 链段的成核效应和 PEG 链段的增塑效应，三嵌段共聚物增强了 PLLA 的结晶，这在很大程度上取决于共聚物的结构。三嵌段共聚物的PLLA链段越短，PEG链段越长，共混物的玻璃化转变温度和冷结晶温度越低，PEG含量越高，结晶度和球晶生长速度越快。然而，具有较长PLLA链段和较短PEG链段的三嵌段共聚物对PLLA显示出独特的成核效应，导致PLLA结晶温度升高。结果证实，PLLA的结晶加速可归因于成核和塑化作用，且塑化作用更为显着。更重要的是，三嵌段共聚物的引入提高了相容性和耐久性，因为即使在高负载下也能与 PLLA 基质良好的界面相互作用。塑化效果更显着。更重要的是，三嵌段共聚物的引入提高了相容性和耐久性，因为即使在高负载下也能与 PLLA 基质良好的界面相互作用。塑化效果更显着。更重要的是，三嵌段共聚物的引入提高了相容性和耐久性，因为即使在高负载下也能与 PLLA 基质良好的界面相互作用。