Designing Self-Healing, Printable, and Tough Conductive Hydrogels via the Synergy of Orthogonal Photochemistry and Hofmeister Effect

Developing conductive hydrogels that combine high toughness, self-healing capabilities, and 3D printing performance is crucial for flexible electronics, but it remains a significant challenge due to the inherent performance trade-offs of traditional manufacturing methods. Herein, we present a synergy of orthogonal photochemistry and Hofmeister effect strategy for the rapid fabrication of high-performance conductive hydrogels. Under visible light, ruthenium photochemistry triggers three orthogonal reactions comprising the radical polymerization of poly(vinyl alcohol acetoacetate), the oxidative polymerization of ethylenedioxythiophene, and the phenol coupling of gelatins within seconds. A subsequent Hofmeister effect-mediated post-treatment induces hierarchical polymer crystallization to endow the hydrogels with exceptional toughness of 3.1 MJ m^-3 and fatigue resistance. Furthermore, the dynamic hydrogen-bonding network and gelatin grant the hydrogel a rapid self-healing efficiency of approximately 90%. The resulting hydrogels are fully compatible with extrusion-based 3D printing to enable the fabrication of customizable and self-healing resistive and capacitive sensors capable of reliable motion monitoring. This work establishes a versatile and efficient platform for engineering multifunctional soft materials for wearable devices.