Flame-Retardant Ionogel Enabled by Lignin Molecular Networks for Fire Rescue

Ionogel intended for fire environments encounters considerable challenges stemming from intrinsic limitations, such as inadequate heat resistance and potential damage to their structural networks. Here, a glycol lignin ionogel (GLI) with integrated flame-retardant, waterproof, and sensing capabilities for smart firefighting auxiliary equipment is presented. The ionogel, synthesized from the molecular network construction of Gly-lignin, 1-butyl-3-vinylimidazole tetrafluoroborate (BVIMBF₄), and benzyl methacrylate (BZMA), forms a stable and elastic 3D conductive network through both chemical and physical crosslinking. This structure imparts remarkable mechanical properties, including considerable adhesion (30.4 kPa on flame-retardant gloves), tensile strength (5.8 MPa), and high ionic conductivity. Notably, through the formation of a protective carbonized/B₂O₃ layer and chemical barrier gases during combustion, the ionogel exhibits excellent flame retardancy, with a weight loss of 41.8% at 800 °C. Additionally, GLI achieves real-time thermal sensing via its negative temperature coefficient (NTC) behavior (TCR = -0.58% °C^-1). Even after exposure to fire, GLI retains its temperature and motion-sensing capabilities. Moreover, GLI demonstrates favorable biocompatibility and environmental degradability, broadening its applicability in sustainable and wearable electronics. The work provides new insights for the preparation of the next generation of fireproof multifunctional intelligent sensors.