Entropy‐Mediated Polymer–Cluster Interactions Enable Dramatic Thermal Stiffening Hydrogels for Mechanoadaptive Smart Fabrics

Abstract

AbstractThermal stiffening materials that are naturally soft but adaptively self‐strengthen upon heat are intriguing for load‐bearing and self‐protection applications at elevated temperatures. However, to simultaneously achieve high modulus change amplitude and high mechanical strength at the stiffened state remains challenging. Herein, entropy‐mediated polymer–mineral cluster interactions are exploited to afford thermal stiffening hydrogels with a record‐high storage modulus enhancement of 13 000 times covering a super wide regime from 1.3 kPa to 17 MPa. Such a dramatic thermal stiffening effect is ascribed to the transition from liquid‐liquid to solid–liquid phase separations, and at the molecular level, driven by enhanced polymer–cluster interactions. The hydrogel is further processed into sheath–core fibers and smart fabrics, which demonstrate self‐strengthening and self‐powered sensing properties by co‐weaving another liquid metal fiber as both the joule heater and triboelectric layer.