Jing Zhanxin, Huang Xiaolan, Liu Xinqi, Liao Mingneng, Zhang Zhaoxia, Li Yong
Department of Applied Chemistry, College of Chemistry and Environment, Guangdong Ocean University Zhanjiang China
RSC Adv. 2022 May 3;12(21):13180-13191. doi: 10.1039/d2ra00461e. eCollection 2022 Apr 28.
In this work, the synthesized PLLA/PCL multi-block copolymers with different compositions were introduced into a stereocomplexed poly(lactide) (sc-PLA) matrix to accelerate the stereocomplexation of PLA enantiomers and improve its inherent brittleness. The PLLA/PCL multi-block copolymers were in different compositions to adjust the molecular weight of the PLLA block. The structure, molecular weight, crystallization behavior, crystal structure and thermal stability of PLLA/PCL multi-block copolymers were investigated. The results indicated that PLLA/PCL multi-block copolymers with controllable structure and composition were successfully synthesized. On this basis, the blends of sc-PLA and PLLA/PCL multi-block copolymers were prepared by solution casting, and characterized. The results revealed that the introduction of PLLA/PCL multi-block copolymers promoted the stereocomplexation of the PLA enantiomers during the melting crystallization process to obtain a complete stereocomplexed material. But the presence of the PCL block leads to a decrease in the melting temperature of the stereocomplex and difficulty in homogeneous nucleation. Compared with sc-PLA, the elongation at break of the blends was significantly improved and their tensile strengths were only slightly reduced. And the thermal stability and mechanical properties of the blends could be adjusted by controlling the content and composition of PCL/PLLA multi-block copolymers. These results revealed that the degree of stereocomplexation and toughness of sc-PLA were improved, which may expand the application fields of PLA-based materials.
在本工作中，将不同组成的合成聚乳酸/聚己内酯（PLLA/PCL）多嵌段共聚物引入立体复合聚乳酸（sc-PLA）基体中，以加速聚乳酸对映体的立体复合作用，并改善其固有脆性。PLLA/PCL多嵌段共聚物具有不同组成，以调节PLLA嵌段的分子量。研究了PLLA/PCL多嵌段共聚物的结构、分子量、结晶行为、晶体结构和热稳定性。结果表明，成功合成了结构和组成可控的PLLA/PCL多嵌段共聚物。在此基础上，通过溶液浇铸制备了sc-PLA与PLLA/PCL多嵌段共聚物的共混物，并对其进行了表征。结果表明，PLLA/PCL多嵌段共聚物的引入促进了聚乳酸对映体在熔融结晶过程中的立体复合作用，从而获得了完全立体复合的材料。但PCL嵌段的存在导致立体复合物的熔融温度降低，且难以均匀成核。与sc-PLA相比，共混物的断裂伸长率显著提高，而拉伸强度仅略有降低。并且可以通过控制PCL/PLLA多嵌段共聚物的含量和组成来调节共混物的热稳定性和力学性能。这些结果表明，sc-PLA的立体复合程度和韧性得到了提高，这可能会扩大聚乳酸基材料的应用领域。
