聚苯乙烯嵌段对左旋聚乳酸/聚苯乙烯-b-右旋聚乳酸立构复合晶结晶行为的调控  

Regulation of Polystyrene Blocks on Stereocomplex Crystallization Behavior of Poly(L-lactic acid)/Polystyrene-b-Poly(D-lactic acid)Blends

作　　者：吴晗 杨顺燚 蒋妮 甘志华[1] Han Wu;Shun-yi Yang;Ni Jiang;Zhi-hua Gan(State Key Laboratory of Organic-Inorganic Composite Materials,Beijing Laboratory of Biomedical Materials,College of Life Science and Technology,Beijing University of Chemical Technology,Beijing 100029)

机构地区：[1]有机无机复合材料国家重点实验室、生物医用材料(北京)实验室、北京化工大学生命科学与技术学院,北京100029

出　　处：《高分子学报》2023年第5期631-642,共12页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号51973010)资助项目.

摘　　要：聚乳酸较差的耐热性和较慢的结晶速率限制了其应用范围的扩展,左旋聚乳酸(PLLA)和右旋聚乳酸(PDLA)共混后形成的立构复合晶(SC)能够促进PLA均质晶(HC)的成核并提高其热稳定性,在改性PLA方面有着巨大应用前景.本研究通过可逆加成-断裂链转移聚合(RAFT)和开环聚合(ROP)法,制备了一系列不同聚苯乙烯(PS)分子量的PS-b-PDLA嵌段共聚物,并将其与PLLA共混,探究了嵌段共聚物及共混物的组成与结晶性能之间的关系.研究结果表明,分子运动性较差的PS嵌段的引入使共混物的结晶更加困难,而低分子量的PS嵌段由于抑制了均质晶(HC)的形成,反而有利于大量立构复合晶(SC)的形成,进而提高了共混物的结晶速率.With the widespread use of poly(lactic acid)(PLA),it has been developed considerably with excellent biocompatibility,biodegradability,and mechanical properties.Nevertheless,the inferior heat resistance and slow crystallization rate seriously restrain the advancement.The stereocomplex crystal(SC),which is formed in the blends of poly(lactic acid)(PLLA)and poly(D-lactic acid)(PDLA),can enhance the homogeneous crystal(HC)nucleation and thermostability of PLA,thus possessing an excellent modification potential.A series of diblock copolymers of PLA and polystyrene(PS)with different molecular weights were synthesized by atom transfer radical polymerization(ATRP)and ring-opening polymerization(ROP).The blends of PLLA/PS-b-PDLA were prepared and the relationship between composition and crystallization of PS-b-PDLA copolymers and their blends was investigated.The results showed that the restriction of PS block on the mobility of PDLA increased with higher molecular weight,which was unfavorable to the crystallization process of PDLA.In the nonproportional blends of PLLA/PS-b-PDLA,the introduction of PS blocks with poor chain mobility contributed to the difficulty in HC,while the low molecular weight PS block was beneficial to accelerate the formation of SC by inhibiting the formation of HC,thereby increasing the bulk crystallization rate.The phase separation occurred in the blends of PLLA/PS-b-PDLA with the same ratio.The high molecular weight PS blocks restricted the mobility of the PLA molecular chain and weakened the contact ability between PDLA and PLLA by separated phase behavior.It inhibited the formation of SC.However,the low molecular weight PS blocks had less restriction on PDLA blocks,thus increasing the crystallinity of SC.The distinctive influence of PS-b-PDLA on HC and SC is significant to the research on the crystallization and thermal properties of PLLA-based composites.And it is of great importance for the performance adjustment of biodegradable materials and the expansion of the application field.

关 键 词：聚乳酸 聚苯乙烯 嵌段共聚物 立构复合 

分 类 号：TQ323.4[化学工程—合成树脂塑料工业]