Shape-memory performance of thermoplastic amphiphilic triblock copolymer poly(D,L-lactic acid-co-ethylene glycol-co-D,L-lactic acid) (PELA)/hydroxyapatite composites

Abstract

Biodegradable polymer/hydroxyapatite (HA) composites are desired for skeletal tissue engineering. When engineered with thermally responsive shape-memory properties, they may be delivered in a minimally invasive temporary shape and subsequently triggered to conform to a tissue defect. Here, the shape-memory properties of thermoplastic amphiphilic poly(D,L-lactic acid-co-ethylene glycol-co-D,L-lactic acid) (PELA) (M w = 120 kDa) and HA-PELA composites are reported. These materials can be cold-deformed and stably fi xed into temporary shapes at room temperature and undergo rapid shape recovery (<3 s) at 50 °C. Stable fi xation (>99% fi xing ratio) of large deformations is achieved at-20 °C. While the shape recovery from tensile deformations slows with higher HA contents, all the composites (up to 20 wt% HA) achieve high shape recovery (>90%) upon equilibration for 10 min at 50 °C. The permanent shapes of HA-PELA can be reprogrammed at 50 °C, and macroporous shapememory scaffolds can be fabricated by rapid prototyping.