Biodegradable Shape-memory Thermoplastic Polyurethanes With a Rigid Sugar Diol

Thermoplastic polyurethane (TPU) has gained widespread applications in many fields. However, recent research focus has shifted from basic performance optimization to multifunctional development of TPU materials. Shape-memory polyurethanes (SMPUs) are one of the most promising intelligent polyurethane materials because of their unique stimulus response and recovery ability. In this study, a series of linear poly(isoidide-2,5-dimethanol urethane)s (PIUs) is developed using poly(ε-caprolactone) (PCL) diol and novel carbohydrate monomers Isoidide-2,5-dimethanol (IIDML), with systematically varied hard segment content ranging from 0% to 30%. The synthesized PIUs demonstrated exceptional mechanical properties, achieving tensile strengths of 14–38 MPa and elongation at break of 964–1286%, along with a suitable melt temperature (45 °C) as the transition temperature. Notably, as the hard segment content increased, the crystallization properties and physical crosslinking density which are determining factors of the shape-memory effect showed an opposite trend. Furthermore, the PIUs showed good hydrolysis effects in pH 1, 7.2, and 13 conditions. These findings demonstrate that precisely adjusting the hard segment content enables the design of biodegradable PIUs with promising potential for shape-memory applications.