New stimulus-responsive shape-memory polyurethanes capable of UV light-triggered deformation, hydrogen bond-mediated fixation, and thermal-induced recovery

Shape-memory polymers (SMPs) have been rapidly developed in recent decades because they can be fixed in deformed shapes and their original shapes can be recovered by applying an external stimulus. There is an urgent need for SMPs that can deform spontaneously upon an external stimulus. Light acts as a remote and clean stimulus for inducing changes in shape, but light-based deformations cannot be fixed under ambient conditions. Here, we report a novel stimulus-responsive SMP that is capable of shape deformation under UV light and shape fixation in visible light. Finally, the original shape is recovered at higher temperature. This work expands the current understanding of the inherent staging-responsive features in both light-and thermal-induced SMPs, illuminating a new mechanism of staging-responsive shape-memory effects.