Oxygen-co-Thermal Driver for Constructing Integrated Anisotropic Hydrogels with Programmable Shape Deformation, Superior Self-Healing, and Mechanical Performance

Gradient hydrogels hold great potential for applications in actuators due to their unique stimulus response performance and simple integrated structure. However, most of the currently available gradient structure programming strategies are dependent on complex external fields and employ a single structural driving force, which limits their further development. In this study, we proposed a novel oxygen-co-thermal driving structure programming strategy for constructing the integrated anisotropic bistructured hydrogels with multifunctionality. Namely, we utilized the simple and low-cost oxygen gradient dissolution behavior and heat transfer behavior in nature as the dual driving force of the gradient structure, combined with the spontaneous existence of electrostatic attraction between polyelectrolyte chains, to construct integrated hydrogels with both gradient and phase separation structures in a one-step method. It was shown that the designed hydrogels exhibited remarkable self-healing ability and mechanical property. Moreover, the hydrogel exhibited superior responsive deformation capability, and the deformation behavior was programmable depending on internal conditions (composition ratio and specific surface area) and external stimuli (pH and temperature). In addition, the successful construction of humidity alarms and grippers by the designed hydrogel demonstrated that our study provides new insights into the field of manufacturing smart actuators.