Stretchable, Highly Sensitive Dual-Network Ionic Organic Hydrogel for Wearable Flexible Sensors and Supercapacitors

Since conventional ionic conductive hydrogels cannot simultaneously possess excellent stretchability, strong conductivity, and high sensitivity, this limits their application in the field of flexible electronics. This paper proposes a facile one-pot method for the preparation to obtain dual-network ionic organic hydrogels. Here, poly(vinyl alcohol) (PVA), acrylamide (AM), cellulose nanocrystals (CNC), tannic acid (TA), and potassium chloride (KCl) were dissolved in dimethyl sulfoxide-water (DMSO/H₂O). The first layer of the chemical cross-linking network was formed by a light-curing free radical polymerization reaction with polyacrylamide (PAM) long chains. Subsequently, through a cyclic freezing-thawing process, the PVA molecular chains formed a second layer of a physically cross-linked network. This dual-network ionic organic hydrogel has excellent tensile properties (603%, 0.26 MPa), good electrical conductivity (3.63 S/m), ultrahigh sensitivity (GF up to 18.74), and a stable resistance temperature coefficient (TCR of 0.455/°C). Therefore, the hydrogel can be successfully used in flexible strain sensors, supercapacitors, and friction nanogenerators to achieve motion monitoring, traceless writing, electric energy storage, and energy conversion. This work provides ideas for the application of ionic organic hydrogels in future flexible electronic devices.