Entropy-Mediated Polymer–Cluster Interactions Enable Dramatic Thermal Stiffening Hydrogels ...
Jia Wu, Baohu Wu, Jiaqing Xiong, Shengtong Sun*, and Peiyi Wu*. Entropy-Mediated Polymer–Cluster Interactions Enable Dramatic Thermal Stiffening Hydrogels for Mechanoadaptive Smart Fabrics. Angew. Chem. Int. Ed. 2022, 61, e202204960.
Thermal 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.