Strengthening the Shape Memory Behaviors of l‑Lactide-ased Copolymers via Its Stereocomplexation Effect with Poly(d‑Lactide)

Biodegradable shape memory polymers (SMPs) have great application prospects in biomedical fields, particularly, those SMPs with the transition temperature of ∼37 °C have attracted keen interests. In this study, poly­(d-lactide) (PDLA) of different molecular weights (5000 or 20 000) was introduced into poly­(l-lactide-co-glycolide) (PLGA) or poly­(l-lactide-co-ε-caprolactone) (PLCL) copolymers at different amounts (5, 10, 15 wt%) to investigate the effect of PLLA/PDLA stereocomplexation (SC-PLA) on the shape memory performance of the blends. The tested copolymers were in different chemical compositions to adjust the lengths of PLLA segments and the glass transition temperatures (T_g). Characterizations on crystallization, mechanical properties, shape fixing, and recovery ratios of the blends were conducted, and the results were discussed to correlate the formation of SC-PLA crystals to the shape memory performances of corresponding blends. It was identified that SC-PLA crystals would act as cross-links and had strengthened the stationary phase within the matrixes, which could significantly improve the shape memory performances of PLGA/PDLA and PLCL/PDLA blends if more SC-PLA crystals had formed. Based on the findings, a kind of porous scaffold was prepared using the PLCL(75:25)/PDLA (5k, 10 wt%) blend, which displayed excellent and reproducible compression and recovery behaviors under 37 °C, showing potentials as body temperature triggered SMPs for in vivo applications such as implantable template to facilitate tissue regeneration.