Biodegradable polyurethane/soy protein shape-memory polymer blends prepared via environmentally-friendly aqueous dispersions

Biodegradable and biocompatible shape-memory polymer blends of soy protein (SP) and polyurethane (PU) based on poly(e-caprolactone) (PCL) has been synthesized using environmentally-friendly aqueous dispersion technique. High-pressure supercritical carbon dioxide (scC02) foaming technique was applied to the blends to generate three-dimensional interconnected porous structures or scaffolds with special enhanced benefits for potential biomedical applications such as soft tissue engineering and/or drug release. Blending PU dispersion (PUD) with SP significantly increased the biocompatibility and biodegradability properties of the materials and improved their shape-memory capability. The PCL soft segment was found to be miscible with SP over the entire range of concentration as confirmed by DSC measurements, where a single Tg located between the Tg of the pure SP and PCL soft segment was observed for all blend concentrations. The shape-memory behavior of the blends was investigated for different concentrations under free-stress condition. The rate of strain recovery was found to be SP concentration dependent. The stress recovery of the blend reached a maximum value at w_SP = 0.1 weight fraction. This finding was attributed to the maximum increase in the degree of crystallinity of PCL soft segment at w_SP = 0.1 as conformed by X-ray analysis.