A Stimuli-Responsive Hydrogel with Reversible Three-State Transition Controlled by Redox Stimulation

A great extent of past work has focused on the development of stimuli-responsive hydrogels that can primarily achieve a two-state transition, such as sol-gel translation. In the current work, a reversible hydrogel with three-state transition is designed. The three transformations between original, oxidized, and reduced states are achieved via controlling the external stimuli conditions. Hydrogels in their original state possess a weak self-healing property and negligible fluidity. The oxidized state hydrogel can keep molding, however, losing the self-healing property. In contrast, the reduced state hydrogels exhibit strong self-healing property. Moreover, the hydrogel becomes injectable subsequent to dithiothreitol addition. Thereafter, under UV-light irradiation or NaClO immersion, the hydrogels can be remolded to any desired shapes. These properties provide novel designing strategies and potential applications for smart and reusable materials.