Thermoplastic polyurethane-based shape memory polymers with potential biomedical application: The effect of TPU soft-segment on shape memory effect and cytocompatibility

Stimuli-responsive biocompatible polymer blends with adjustable properties are highly desirable for biomedical applications. It is crucial to meticulously consider the chemical structure and composition of each polymer to prepare a melt-miscible blend system that possesses desirable shape memory and cytocompatibility performance. Herein, we developed thermo-responsive SMPs by melt-blending Polycaprolactone (PCL) with two different Thermoplastic polyurethanes (TPU) composed of the same hard segment, but different soft segments derived from adipic acid polyester and polycaprolactone diols and the critical role of TPU chemical structure on the thermomechanical properties and biocompatibility of TPU-based SMPs were investigated and uncovered. Cyclic thermomechanical tests show that compared with adipic acid-based TPU/PCL blends, PCL diol-based TPU/PCL blends exhibit remarkable shape memory properties (Rf and Rr >90%) with the ability to start recovery at lower temperatures (∼45 °C), while the cytotoxicity and wettability studies implied higher biocompatibility and hydrophilicity of adipic acid-based TPU/PCL blends making them more favorable substrates for cell proliferation.