Preparation of poly(lactic acid)-based shape memory polymers with low response temperature utilizing composite plasticizers

In this paper, we synthesized a triblock oligomer of poly(lactic acid) (PLA) and poly(e-caprolactone) (PCL) by direct polycondensation of L-lactic acid and then condensation reaction with PCL diol. Then, the triblock oligomer was chain-extended with diisocyanate, and the PLA-based thermoplastic elastomer (PLATPE) with high toughness and high ductility at room temperature was synthesized. The synthesized PLATPE and a partially biodegradable elastomeric poly(e-caprolactone) polyurethane (PCLTPU) were used to prepare PLA-based shape memory polymer materials by melt blending with PLA resin. The morphologies, thermal properties, and shape memory properties of the two kinds of shape memory polymers were characterized. The results shows that the shape fixation rates of two systems are more than 95%. The shape recovery rate of PLA/PCLTPU can reach to 95%, while that of PLA/PLATPE is slightly higher than 80%. By adding composite plasticizers, the PLA/PCLTPU shape memory polymer system with better thermal stability was further modified to prepare a low-temperature-response shape memory polymer. When 10 wt% compound plasticizer (5 wt% Polysorb, 5 wt% ATBC) were added, the deformation recovery rate of PLA/PCLTPU = 80/20 can reach more than 90%, the shape fixation rate can be close to 100%, and the deformation recovery temperature can be reduced to around 40 °C. The biodegradable and biocompatible PLA-based shape memory polymer with low response temperature may have a potential application prospect in the field of biomedical materials.