Ion Cross-Linked High-Strength and Toughness Multinetwork Ionic Organic Hydrogels for Flexible Electronic Devices

Abstract

Because traditional ionic conductive hydrogels cannot simultaneously exhibit excellent tensile properties, strong conductivity, and high sensitivity, their application in the field of flexible electronic devices is limited. To address this issue, this paper proposes a simple one-pot method to prepare multinetwork ionic organic hydrogels. Here, poly(vinyl alcohol) (PVA), acrylamide (AM), hydroxyethyl cellulose (HEC), sodium alginate (SA), and zinc chloride (ZnCl₂) are dissolved in a dimethyl sulfoxide-water mixture (DMSO/H₂O). First, through photopolymerization of free radicals, PAM long chains form the first layer of a chemically cross-linked network. Subsequently, the SA molecular chain chelates and coordinates with Zn²⁺ to construct a second layer of an ion cross-linked network. Finally, during the continuous freeze–thaw process, PVA molecular chains form a third layer of a physically cross-linked network. The resulting multinetwork ionic organic hydrogel demonstrates excellent tensile properties (330%, 1.26 MPa), good conductivity (3.21 S/m), high sensitivity (GF can reach 8.19), a stable resistance temperature coefficient (TCR of 0.682/°C), and working stability in different pH environments. Therefore, the hydrogel can be successfully applied in flexible strain sensors, supercapacitors, and friction nanogenerators to enable motion monitoring, traceless writing, electric energy storage, and energy conversion. This work provides a novel approach for the application of ionic organic hydrogels in future flexible electronic devices.