Structurally engineered lignin-based robust, conductive ionic hydrogels via DMSO-assisted dual-network strategy for...

Electronic skins and wearable sensors exhibit enormous application potential in emerging fields such as human health monitoring and human-machine interaction. Ionic hydrogels are promising soft conductors for electronic skins and wearable sensors, but they suffer from weak mechanical performance, swelling, and unstable ionic conduction in practical scenarios. Here, we propose a DMSO-assisted dual-network strategy for constructing lignin-based ionic hydrogels that integrate robustness, high ionic conductivity, and antibacterial activity. Alkaline lignin is modified into a multifunctional building block (LigBM₃-C₁₆) with crosslinkable sites and antibacterial property via esterification and quaternization. Copolymerization of LigBM₃-C₁₆ with acrylic acid and acrylamide in DMSO forms a homogeneous covalent DMSO gel, followed by FeCl₃ solvent exchange to capture Fe³⁺ on uniformly phenolic and carboxylic groups from lignin and acrylic acid, forming a continuous hydrate coordination network. The resulting LigBM₃-C₁₆-Fe hydrogels exhibits excellent tensile strength (3.38 MPa) and toughness (9.76 MJ m^-3) and ionic conductivity (σ = 27.4 mS cm^-1), overcoming the typical trade-off between robustness and ion transport. Fe³⁺ coordination and quaternized lignin together provide broad-spectrum antibacterial/antioxidant activity. The resulting ionic hydrogel functions as stable strain sensors for real-time human motion monitoring and gesture-controlled human-machine interaction, offering a simple method to robust, multifunctional ionic hydrogels for flexible conducting materials.