High-strength and environmentally stable wood conductive eutectogels enabled by metal-based deep eutectic solvents

Abstract

Conductive gels hold significant promise for applications in flexible sensing and wearable electronics, yet face the challenge of limitations in mechanical strength and environmental stability. Herein, a facile and effective strategy was proposed to fabricate high-performance eutectogels by introducing metal-based deep eutectic solvent (MDES) consisting of zinc chloride (ZnCl₂), ethylene glycol (EG), and acrylic acid (AA) into the wood skeleton (WS), which was extracted from natural wood, followed by in-situ ultraviolet (UV)-initiated polymerization. The resulting metal-based deep eutectic solvent/wood skeleton eutectogels (MDES/WS eutectogels) exhibited high ionic conductivity (2.82 × 10^–2 S/m), higher than most conventional wood-based gels, benefiting from the inherent conductivity of the MDES, as well as the aligned micro and nanochannels in WS that facilitate ion transport. Moreover, the synthesized polyacrylic acid (PAA) network could form strong interfacial interactions with the cellulose nanofibers through hydrogen bonding and Zn²⁺ coordination cross-linking, significantly reinforcing the eutectogels with a high tensile strength of 41.50 MPa and toughness of 8.4 MJ/m³, while still demonstrating good environmental stability (–60 to 100 °C). Leveraging its high conductivity, robust mechanics, and environmental stability, the developed eutectogels functioned as flexible sensors to generate stable and responsive electrical signals during simulated human movements and possessed potential as a programmable information transmission interface through Morse code input. This work established a novel paradigm for developing sustainable, mechanically robust, and environmentally stable conductive gels, offering a versatile platform for next-generation flexible electronics operable under extreme conditions.