Synthesis and Characterization of Poly(D,L-Lactide)-Based Shape Memory Polymers

Biodegradable novel poly(D,L-lactide)-based shape memory polymers (SMPs) were prepared from poly(D,L-lactide) (PDLLA) Diols, hexamethylene diisocyanate(HDI) and butanediamine(BDA) via two steps polymerization reaction. Its thermal, mechanical properties and shape-memory behaviors were investigated by means of differential scanning calorimetry, stress-strain measurements and bending test. The glass transition temperature of the SMPs changes with composition from 38 to 45 C which close to body temperature in a predictable manner. These type SMPs can achieve the high modulus and tensile strength, and their elongation at break can be greater than 500% at lower hard segment content. All SMPs display excellent shape-memory properties. When a deformation temperature 20 C above T, was chosen, the ratio of the shape-memory fixation approximately 100%, and the recovery ratio was 95-100%. Meanwhile, the recovery time is relevant to the recovery temperature, the recovery time decrease with increasing the recovery temperature. By adjusting the composition of SMPs, the recovery temperature could be adjusted to the neighborhood of the body temperature and it can be designed as potential biomaterials for use in biomedical fields.