Photoinduced triple shape memory polyurethane enabled by doping with azobenzene and GO
A polymer-dispersed azobenzene and GO nanocomposite film was fabricated with shape memory polyurethane as a matrix. Upon mechanical stretching, the nanocomposite film exhibited a photoresponsive triple shape-memory effect by successive exposure to UV and NIR light. Here, azobenzene and GO may act as photo-harvesters for UV and NIR light, respectively, and their photoresponsiveness was transferred to the host polymer films. On one hand, UV light caused the photomechanical motion of azobenzene materials, leading to the photoinduced bending behavior for the composite film. On the other hand, NIR brought about the photothermal effect of GO, heating the film and triggering the thermoresponsive shape-memory of polyurethane. The nanocomposite film showed good mechanical properties, which can be self-healed upon NIR irradiation. Benefitting from these light-directed triple shape-memory properties, simulation of flower blooming and fading was successfully achieved, indicating its potential application as a biomimetic actuator and other functional devices.