不同构型聚乳酸共混体系的立构复合结晶研究进展

摘要

左旋聚乳酸（PLLA）和右旋聚乳酸（PDLA）在共混体系中可形成立构复合（sc）结晶，与聚乳酸（PLA）同质结晶材料相比，sc结晶材料具有良好的耐热性和耐化学稳定性。因此，sc结晶是改善PLA综合性能的一种有效手段。但在 PLLA/PDLA 共混体系中，存在各自的同质结晶与两者之间 sc 结晶的竞争，所以制备高耐热 sc 型PLA材料的关键之一是理解其sc结晶的形成条件与机理，进而调控和促进其sc结晶程度。在PLLA/PDLA共混物中，sc 结晶受聚合物化学结构、结晶与加工条件等诸多因素影响，其影响规律和机理较复杂。根据 PLLA/PDLA共混物sc结晶行为影响因素的不同，从聚合物分子量、立构规整性、共混比例、分子链拓扑结构、结晶方式与条件、加工助剂和其他组分加入6个方面出发，详细综述了PLLA/PDLA共混物sc结晶及其sc材料制备的研究进展，以期为高耐热生物基PLA材料的加工制备提供指导。%Poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) can form stereocomplex (sc) crystallites in their racemic blends. Compared to the homocrystalline poly(lactic acid) (PLA), sc-type PLA has much better heat and chemical resistances. Therefore, sc crystallization of PLA has been an effective method to improve its physical properties. However, the formations of homo and sc crystallites are competing in the crystallization of PLLA/PDLA racemic blends. A critical issue to prepare the heat-resistant sc-type PLA is to understand the formation conditions and mechanism of sc crystallization, and further to control and promote the extent of sc crystallization. Sc crystallization is affected by a variety of factors such as the chemical structure of polymer component, crystallization and processing conditions in PLLA/PDLA racemic blends, and their influential mechanisms are very complicated. According to the various factors influencing sc crystallization, this paper will review the research progress of sc crystallization behavior and preparation of sc materials for PLLA/PDLA blends in recent years from the aspects of polymer molecular weight, stereoregularity, blend ratio, polymer topology, crystallization method and condition, and addition of additive or other components. It is expected that this review can provide a theoretical guideline for the preparation of heat-resistant biobased PLA materials.