Multifunctional polyoxometalate-based conductive hydrogels for low temperature tolerant, flexible wearable electronics

Abstract

The advancement of flexible wearable electronics demands materials that integrate high conductivity, exceptional mechanical flexibility, and broad environmental adaptability. Although polyoxometalate (POM)-based conductive hydrogels hold great promise, their application is impeded by two critical limitations: poor interfacial compatibility between POMs and polymer matrices, and significant conductivity degradation at low temperatures. To address these issues, we designed a POM-based proton-conductive hydrogel (PVA/P(SBMA-AM)/PW₁₂/PA (PSAWA)) by incorporating zwitterionic sulfobetaine methacrylate (SBMA), phytic acid (PA), and H₃PW₁₂O₄₀ (PW₁₂) into a poly(vinyl alcohol) (PVA)-poly(acrylamide) dual-network matrix. SBMA enhances the loading and dispersion of PW₁₂ within the hydrogel via an electrostatic–steric synergistic mechanism. Concurrently, PA synergizes with PW₁₂ to ensure fast proton migration even at low temperatures by constructing proton-conduction pathways with reduced energy barriers. These design strategies endow the PSAWA hydrogel with ultrahigh proton conductivity (2.71 × 10⁻¹ S cm⁻¹ at 25 °C; 1.06 × 10⁻² S cm⁻¹ at −40 °C), alongside high stretchability, remarkable self-healing capability, effective antibacterial activity, and excellent biocompatibility. Furthermore, flexible biosensors and supercapacitors fabricated using the PSAWA hydrogel demonstrate outstanding performance even at −40 °C. This work offers new insights for developing proton-conductive hydrogels with low-temperature adaptability for wearable electronics.