Autonomous Shapeshifting Hydrogels via Temporal Programming of Photoswitchable Dynamic Network

Responsive materials typically require external stimulation for triggering. In contrast, temporal programmable materials exhibit autonomous trigger-free responses that are uniquely attractive. Its largely under-explored molecular enabling mechanisms, however, prohibit its expansion into functionally diverse devices. We illustrate here that the dynamic ionic bonds within a tough hydrogel can be an effective and generally applicable mechanism for temporal programming. This leads to an unusual shapeshifting behavior that can be precisely manipulated without requiring any external triggering. Further incorporation of photoswitchable dynamic disulfide bonds in the hydrogel network introduces another mechanism for the spatial control of the geometric shapeshifting pathway. The synergistic effect of temporal programmability and photodefinability allows access to multifunctional shapeshifting devices with versatility beyond conventional systems.