Facile Fabrication of Tough, Low-Temperature Flexible Conductive Hydrogels via Solvent Competition-Induced Crystallization

Traditional hydrogels face significant limitations in practical applications due to their inherent weaknesses in mechanical strength, functional versatility, and environmental stability. Here, we develop a solvent competition-induced crystallization strategy for one-step fabrication of multifunctional poly(vinyl alcohol)-poly(acrylic acid) (PVA–PAA) hydrogels. By precisely controlling the phase separation process through the differential solubility of PVA in dimethyl sulfoxide–water binary solvents and PAA-mediated regulation, we construct a hydrogen-bond-cross-linked network with uniformly distributed crystalline domains. The resulting hydrogel exhibits exceptional mechanical properties comparable to natural rubber, including remarkable toughness (14 MJ/m³), high tensile strength (3.68 MPa), and extreme stretchability (>950%). Beyond mechanical robustness, the material demonstrates multifunctional integration, featuring intrinsic ionic conductivity (0.27 S/m) with simultaneous antibacterial efficacy (≈80% inhibition against S. aureus), cryoprotective capability for stable operation at −70 °C, and long-term moisture retention (85% after 4 days). When employed as a flexible strain sensor, the hydrogel maintains stable sensitivity (gauge factor = 1.23) across 0–500% strain, even under extreme cryogenic conditions. This study not only advances a fundamental understanding of solvent-mediated crystallization dynamics but also establishes a versatile platform for developing robust, environmentally adaptive hydrogels through a facile fabrication process, thereby addressing critical challenges in wearable electronics and biosensing technologies.