含柔性链段的嵌段共聚物调控聚乳酸纤维的结构和性能研究

聚乳酸（PLA）纤维的韧性和耐热性差是制约其发展的两大瓶颈，如何改善其综合性能成为该领域的研究重点。本项目以右旋聚乳酸（PDLA）与软段聚乙二醇（PEG）的三嵌段共聚物（PDLA-b-PEG-b-PDLA）为改性剂，开展左旋聚乳酸（PLLA）共混纤维的结构和性能研究。主要内容包括：（1）采用先进的原位表征技术，系统研究PLLA/PDLA-b-PEG-b-PDLA共混物在拉伸和热处理条件下的多级微观结构的形成机制，重点阐明立构晶、α晶以及软段在应力条件下的相互作用机制；（2）根据理论研究结果，调控共混物的组成和熔融纺丝工艺，制备出不同结构的PLLA共混纤维，探讨立构晶和软段在材料耐热、韧性、强度等性能上所发挥的作用，阐明立构晶和软段协同提高PLLA纤维性能的机理。通过上述研究，获得对含柔性链段的嵌段共聚物协同改性PLA机理的新认识，实现耐热的柔性PLA纤维制备，拓宽生物可降解材料的改性途径。

The toughness and thermal stability are two bottlenecks for the application poly(lactic acid) (PLLA) fibers, which severely restrict their application. This project focuses on the structure mediation and properties of PLLA fibers modified by a PDLA-b-PEG-b-PDLA triblock copolymer. The main contents include: (1) the formation and evolution of multi-level microstructures during stretching and annealing will be systematically investigated with advanced in-situ characterization techniques. The interaction mechanism between stereocomplex crystals, α crystals and the soft chains under external fields will be elucidated. (2) On basis of the above results, PLLA fibers with different microstructures will be prepared by regulating the blend composition and melt spinning process. The effects of stereocomplex crystals and soft chains on the properties including thermal stability, toughness and strength will be explored systematically. The research will bring new understanding of synergistic enforcing mechanism considering stereocomplex crystals and soft block of the triblock copolymer in the blend. Meantime, flexible PLLA fibers with excellent thermal stability will be obtained. The output of the project will provide a technical reference for preparing modified biodegradable polymers with excellent properties.