Preparation and Properties of Poly-L-Lactide/Poly-D-Lactide Stereocomplex Shape Memory Polymers

With the increasing scarcity of petroleum resources and the continuous deterioration of global environment due to the extensive application of petroleum-based polymers, the development of shape memory polymer functional materials based on green and sustainable biopolymers have attracted increasing attention. In this study, via facile and environmental melt blending, the incorporation of PDLA into PLLA matrix gives rise to the in-situ formation of polylactide stereocomplex (sc-PLA), and the homogeneous dispersion of sc-PLA enhances the shape memory performance of PLLA, consequently obtaining the totally biodegradable PLA-based shape memory functional materials. With the incorporation of only 1% PDLA into PLLA matrix, the in-situ formation of sc-PLA is achieved and the sc-PLA content increases with the increasing PDLA content. The thermal-mechanical results indicate that the formation of sc-PLA has few influence on glass transition temperature of PLLA/PDLA blends and can enhance the strorage modulus at the high temperature effectively. And the shape memory results manifest that both pure PLLA and PLLA/PDLA blends with various composition ratios represent excellent shape fixing performance (Rf≈100%), but the value of the shape recovery ratio of PLLA/PDLA blends is increased firstly and then decreased with the increasing PDLA content. When the PDLA mass fraction reaches to 3%, the PLLA/PDLA blend obtain the optimal shape memory performance (Rr≈85.31%), and the shape memory performance of PLLA/3PDLA blends can keep constantly even after repeated shape memory tests under the invariable test condition. In conclusion, the biodegradable PLA-based shape memory functional materials have been successfully achieved via simple and facile melting blend, and the application of sc-PLA as physical network point in shape memory functional materials can be broaden, consequently offering a new strategy to the structure design of PLA-based shape memory functional materials. © 2021, Editorial Board of Polymer Materials Science & Engineering. All right reserved.