Phytic acid-regulated polyoxometalate-based conductive hydrogels for low temperature flexible devices

A PA-regulated CS/PW 12 interfacial strategy was developed to construct homogeneous POM-based conductive hydrogels. • The CSAWA hydrogel achieved high proton conductivity of 1.05 × 10 −1  S cm −1 at 25 °C and 5.13 × 10 −3  S cm −1 at −40 °C. • CSAWA hydrogel exhibits anti-freezing, adhesive, self-healing, antibacterial, and cytocompatible properties. • CSAWA enables strain sensing, ECG monitoring, and wide-temperature solid-state supercapacitors. The development of flexible wearable sensors and energy storage devices requires materials that integrate stable conductivity, reliable adhesion, good biocompatibility, and cold tolerance. Polyoxometalate (POM)-based proton-conductive hydrogels are promising for both proton transport and electrochemical functionality, yet their low-temperature performance is limited by unstable POM dispersion, weakened interfacial adhesion, and reduced charge transport. Incorporating chitosan (CS) can improve bioadhesion and biocompatibility; however, strong local association between protonated CS chains and anionic POM clusters may promote POM aggregation and network heterogeneity. Here, we designed a multifunctional CS/sulfobetaine methacrylate (SBMA)/acrylic acid (AA)/POM H 3 PW 12 O 40 (PW 12 )/phytic acid (PA) hydrogel (CSAWA hydrogel). Within this network, SBMA promotes hydration, chain flexibility, and proton transport, while AA provides carboxyl groups for reversible hydrogen bonding and network stabilization. PA mediates the local interactions among CS, PW 12 , and the surrounding polymer network, thereby improving PW 12 dispersion, while its multipoint interactions with CS help maintain adhesion at low temperature. Meanwhile, its phosphate groups provide acidic proton sites and hinder free-water crystallization, thereby preserving proton transport under cold conditions. The CSAWA hydrogel exhibited high proton conductivity, excellent stretchability, rapid self-healing ability, stable adhesion, effective antibacterial activity, and good cytocompatibility. Moreover, CSAWA-based wearable strain sensors, electrocardiogram (ECG) electrodes, and flexible solid-state supercapacitors showed reliable performance under low temperatures. This work presents a molecular interaction-regulation strategy for integrating proton conduction, adhesion, cold tolerance, and electrochemical functionality within conductive hydrogels.