Tunable shape memory of thermoplastic polyurethane/poly(lactic acid) blends via morphology control: Performance and mechanism

While poly(lactic acid) (PLA) originating from natural resources is considered to be a promising sustainable material for the fabrication of shape-editable biomedical devices, the shape recoverability is limited by its intrinsic brittleness. In this work, shape memory blends were fabricated by modifying PLA with a toughen agent of thermoplastic polyurethane (TPU). After blending with TPU, the tensile toughness of PLA was significantly improved, resulting in an enhancement of original shape recovery but a deterioration of temporary shape fixation. In particular, the co-continuous structured blend bearing 50 wt% TPU showed the best comprehensive shape memory capacity with balanced shape-fixing and -recovering ratios. The research on the underlying mechanism revealed that the continuous phases and rich interfaces in co-continuous structure promoted load distribution and force transferring, both of which optimized the shape memory effect. Also, regarding to the good biocompatibility of TPU and PLA, the produced materials are potential to be applied in the biomedical engineering field.