In Situ Hofmeister Effect in Polymer Solution by Hydrophobic I₃^- for Multifunctional Hydrogel

Multifunctional hydrogels are widely applied in flexible electronics, energy devices, and sensors due to their unique physical and chemical properties. However, most hydrogels, particularly multifunctional ones, often require complex and time-consuming synthesis processes. Herein, we report a quadruple-functional hydrogel with complete reconstructability (6 cycles, dry fragments), self-healability (100 cycles, wet fragments), ultraextension (retaining >150-fold biaxial extension after reconstruction or self-healing), and redox-activity, synthesized via a simple and rapid method. This approach introduces hydrophobic I₃^- (endogenously generated from I₂ and I^-) directly into the polymer solution to trigger the Hofmeister effect in situ, eliminating conventional steps such as cooling-induced shaping and prolonged immersion. Capacitive sensors and self-powered temperature/strain sensor systems by this hydrogel completely retain their original performance after being rebuilt and self-healing. This work demonstrates a facile and efficient strategy for synthesizing multifunctional hydrogels, paving the way for their practical and delicate applications.