嵌段比对左旋聚乳酸基立构复合物结晶行为及形貌的影响

The influence of block ratio on crystallization behavior and morphology of PLLA-based stereocomplex

聚乳酸具有优异的生物相容性及生物可降解性,是热塑性塑料理想的替代品,但结晶性、耐热性较差等缺点限制了其发展。本文以左旋聚乳酸(PLLA)为聚合物基体、右旋聚乳酸-聚乙二醇-右旋聚乳酸(PDLA-PEG-PDLA)三嵌段共聚物作为改性剂,通过溶液共混方法制备了PLLA/PDLA-PEG-PDLA共混物。通过红外光谱(FTIR)、X射线衍射(XRD)、差示扫描量热仪(DSC)和偏光显微镜(POM)研究了PDLA-PEG-PDLA的嵌段比变化对PLLA基共混物结构、结晶行为和结晶形貌的影响。结果表明,PDLA-PEG-PDLA三嵌段共聚物的添加,共混体系生成了PLA立构复合结构,其晶体结构、结晶行为与形貌与纯的PLLA相比均产生了较大的差异。而且,嵌段共聚物的嵌段比的改变也对PLLA/PDLA-PEG-PDLA共混物的结构、结晶行为与形貌产生了较大的影响。

PLA is an ideal substitute for thermoplastic due to its excellent biocompatibility and biodegradability,but its poor crystallinity and low heat resistance limit its development.In this work,PLLA/PDLA-PEG-PDLA blends were prepared by solution blending using poly(L-lactide)(PLLA)as polymer matrix and poly(D-lactide)-poly(ethylene glycol)-poly(D-lactide)(PDLA-PEG-PDLA)triblock copolymer as the modifier.The influences of block ratio of PDLA-PEG-PDLA on the structure,crystallization behavior and crystal morphology of PLLA-based blends were studied by FTIR,XRD,DSC and POM.The results show that the PLA stereocomplex was formed due to the addition of PDLA-PEG-PDLA triblock copolymer,and its crystal structure,crystallization behavior and morphology were significantly different from that of pure PLLA.Moreover,the change of block ratio of block copolymer also had great influences on the structure,crystallization behavior and morphology of PLLA/PDLA-PEG-PDLA blends.