UV–vis–NIR light-induced bending of shape-memory polyurethane composites doped with azobenzene and upconversion nanoparticles

Abstract

Recently, shape-memory materials (SMMs) have attracted considerable attention due to their superior properties and potential applications. Up to now, the UV–vis–NIR photochemical response for SMMs still remains a challenge. Here, UV–vis–NIR photo-activated composites are successfully prepared via incorporating an azobenzene compound 4-cyano-4′-pentyloxyazobenzene (5CAZ) and upconversion nanoparticles (UCNPs) into shape-memory polyurethane (SMPU) matrices. The mechanically-stretched composite films exhibit photomechanical bending deformations when exposed to UV/vis/NIR light and shape recovery on heating. Furthermore, the biomimetic finger bending can be successfully achieved via light irradiation on different regions of the film, which would pave a path towards biomimetic actuators and functional devices owing to the unique UV–vis–NIR photochemically responsive and shape-memory properties.