Double Network Ionic Conductive Hydrogel With Polyaniline Waterproof Shell for Stable and High‐Performance Wearable and Underwater Sensors

Ionic conductive hydrogels have broad application prospects in the field of stretchable and flexible electronic products. Among them, salt ion conductive hydrogel has the advantages of high conductivity, simple preparation and low cost, but salt ions are easy to diffuse into the water environment through concentration gradient, and the evaporation of water will lead to salting out. A core-shell strategy is designed, in which the hydrophobic conductive network of polyaniline (PANI) is in situ constructed as a waterproof shell outside the freezing cross-linking and salting out polyvinyl alcohol (PVA) ionic conductive hydrogel (PVA-salt-PANI). This shell effectively locks in water and ions inside, suppressing salt precipitation and ion loss. The obtained PVA-salt-PANI hydrogel has excellent electrical conductivity (5.31 S m^-1), good viscoelasticity, temperature resistance, frost resistance (-40°C unfrozen) and self-regeneration ability. Due to the synergistic effect between the dual network polymer chains, it has excellent fracture strain (1784.01%) and tensile strength (10.17 MPa). The environmental stability and versatility of PVA-salt-PANI hydrogel enable it to be used as a human motion sensor, and its waterproof property can reliably sense even in underwater environments. This work provides a novel design strategy for multifunctional sensors that operate reliably under harsh conditions.