Thermo-hydration driven shape-memory hydrogel with functional cellulose for smart vascular stent.

Vascular stents fabricated from shape memory polymers (SMPs) are gaining increasing attention as a potential solution for arterial diseases. The primary challenge lies in constructing SMPs that respond at physiological temperature (37 °C). Considering water's modulation effect on intermolecular forces, we expect to develop a physiological temperature responsive SMP that triggers shape shifting from temporary shape to permanent shape in thermo-hydration environments (37 °C). To achieve this objective, we synthesize a waterborne polyurethane/cellulose nanocrystal composite (WPCx, where x represents wt% of CNC relative to WPU) through solvent-assisted self-assembly of waterborne polyurethane (WPU) with uniformly dispersed cellulose nanocrystals (CNCs) as reinforcing fillers. Molecular dynamics simulations reveal that CNC-WPU interfacial interactions convert cohesive chain attraction into steric repulsion under thermo-hydration conditions, enabling programmable shape recovery at 37 °C with 95.2 % efficiency. Crucially, CNC dispersion reduces surface energy, accelerating water diffusion kinetics, and enhancing hydrophilicity. Due to the superior shape memory capabilities, mechanical properties, biocompatibility and effective drug release, WPCx can be used not only to prepare stents but also to guide the exploration of potential applications of SMPs.