Super Stretchable Gelatin/Poly (ionic liquid) Hydrogel Enabled by Weak Hydrogen Bonds and Microphase Separation towards Multifunctional and Self-powered Sensors

Abstract

The development of conductive hydrogels with high stretchability, anti-crack propagation, stability in aqueous environments, anti-freezing capabilities, and ionic conductivity is important for wearable electronics, such as motion, health monitoring sensors and flexible power generators. However, achieving these combined properties of hydrogel remains challenging. This study introduces an ultra-stretchable conductive hydrogel synthesized via one-pot polymerization composed of gelatin and poly (ionic liquid) (GAHT hydrogel). The GAHT hydrogel exhibits a bicontinuous phase-separated structure at nano scale with multiple physical bonds, which confers GAHT exceptional stretchability (up to ~4000% tensile strain) and high toughness, with a fracture energy of 5461.41 J/m² and anti-swelling property. Additionally, the ionic liquid component imparts excellent anti-freeze properties (functional down to -30 °C), conductivity (1.70 S/m), and antibacterial efficacy, with over 97% activity against E. coli and S. aureus. Based on the excellent properties of the GAHT conductive hydrogel, the amphibious strain sensors, temperature sensors, and triboelectric nanogenerators developed from the GAHT hydrogel exhibit outstanding cyclic stability and a broad range of applicable environments. In conclusion, these multifunctional properties make GAHT hydrogel a promising candidate material for highly stretchable wearable sensors, health and sports monitoring devices, underwater communication, and electric generator.