Ultra-stretchable, robust, self-healable conductive hydrogels enabled by the synergistic effects of hydrogen bonds and ionic coordination bonds toward high-performance e-skins

Abstract

• The conductive hydrogel shows high transparency, superior self-healing efficiency, and good mechanical properties. • The hydrogel-based resistive-type sensor features a wide detection range, rapid response, and consistent output stability. • The hydrogel-based capacitive sensor exhibits linear response, high sensitivity, and excellent cycling stability. • This work advances the development of ionic conductive hydrogel as flexible and wearable electronic devices. Ionic conductive hydrogels as electronic skins (e-skins) have showcased pivotal potentials in the realm of human health monitoring and human–machine interfaces. However, developing intelligent hydrogel with remarkable stretchability and mechanical elasticity is yet challenging. Herein, high-performance ion-conducting hydrogels with unprecedented mechanical properties and good transparent, conductive, self-healing properties are constructed via free-radical polymerization of acrylic acid (AA) within the polyvinyl alcohol (PVA) network, and the subsequent freeze–thaw (F-T) treatment and Zr 4+ ion immersion crosslinking technique. Profiting from the synergy of multiple intermolecular/intramolecular hydrogen bonds between different polymers and coordination bonds of carboxyl-Zr 4+ , the resultant PVA/PAA/Zr 4+ hydrogel exhibits high transparency (∼97 %), superior conductivity (0.6089 S/m), a long elongation at break (2053 %), robust self-healing efficiency (96.3 %), high deformation-tolerate property, and notable mechanical repeatability. These multifaceted attributes render the hydrogel to serve as an ionic conductor for capacitive/resistive −type strain sensor. The hydrogel-based resistive-type strain sensor features a wide detection range (0.5 %-800 %), rapid response time (150 ms), long-term stability, and consistent output stability, making it promising in monitoring diverse human motions and seamless human–machine interactions. Additionally, the hydrogel sensor demonstrates excellent linear response in ultra-wide range (0–900 % strain), high sensitivity, and excellent cycling stability in a capacitive mode, enabling to be used for accurately detecting the weights of objects. As such, this work advances the development of ionic conductive hydrogel as flexible and wearable electronic devices.