Wearable flexible ionic gel based on ionic liquids with high flame-retardancy and multimodal sensing

The complex scenarios and harsh conditions encountered during firefighting missions impose higher demands on functional materials. Polymer ionic liquid (PIL) gels exhibit significant potential for application in extreme environments due to their outstanding performance characteristics. This study synthesizes a novel carboxyl-functionalized PIL composite gel using a green ultraviolet cross-linking method, optimizing its molecular design to enhance the hydrogen bond network significantly. This optimization results in improved mechanical strength, adhesion, and self-healing capabilities. The multi-network structure ensures the stability of the material, while uniformly dispersed fluorophosphate imidazolium compounds confer excellent flame retardancy (limiting oxygen index LOI = 43 %) and antibacterial efficacy (>98 %), making it suitable for extreme firefighting conditions. Thanks to its unique temperature and strain response characteristics, this composite gel can establish a multifunctional sensing platform, enabling real-time monitoring, motion tracking, electrocardiogram (ECG) and electromyogram (EMG) signal acquisition, and wearable device control. Notably, the resistance variation rates of PIL ionic gels with different thicknesses show significant differences, deepening the understanding of the relationship between the microstructure of ionic gels and their electrical transport properties. Finite element analysis supports the material's hydrogen bonding mechanisms, adhesion principles, and sensing mechanisms. This gel material integrates structural stability, self-adhesion, antibacterial properties, and flame resistance, providing innovative solutions for emergency rescue and smart sensing technologies, thereby significantly enhancing the safety and operational efficiency of firefighters.