Ionic hydrogels synthesized from ionic liquid/water binary solvent systems: Demonstrating superior antifreeze and moisture retention capabilities for self-powered wearable strain-sensing applications

Hydrogel-based flexible wearable devices have garnered considerable attention in recent years owing to their inherent mechanical compliance and superior sensing functionalities. Nonetheless, hydrogels confront significant challenges, such as their propensity to freeze at subzero temperatures, inadequate moisturizing capacity, and dependence on external power sources. Herein, a novel hydrogel was developed by incorporating poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and single-walled carbon nanotubes (SWCNTs) into a cellulose nanocrystal (CNC)-doped poly(vinyl alcohol) (PVA)/borax ionic hydrogel (PS@PE) within an ionic liquid (IL)/water binary solvent system. The ionic hydrogel (PS 20–2 @PE 4/6 ) maintains an excellent performance at either ultra-low temperature (−50 °C)，demonstrating superb sensing performance. Furthermore, this ionic hydrogel (PS 20–2 @PA 4/6 ) demonstrated notable stability, retaining over 80.80 % of its original mass after 60 d of storage under open-air conditions. Significantly, PS 20–2 @PE 4/6 displayed remarkable thermoelectric performance, achieving a power factor of 6.43 ± 0.06 μW·m −1 ·K −2 . With its antifreeze capability, moisture retention, and self-powered characteristics, this multifunctional ionic hydrogel holds substantial potential for applications in intelligent wearable strain-sensing devices. This multifunctional ionic hydrogel holds great promise for advancing next-generation self-powered, extreme-environment-resistant wearable devices, offering revolutionary solutions for medical monitoring, human-machine interaction, and polar/space exploration.