A high-thermopower ionic hydrogel for intelligent fire protection

Abstract

High fire-safety and sensitive temperature-response materials are urgently needed for the development of intelligent fire protection. Herein, a multifunctional flame-retardant ionic hydrogel (HTIG) with high thermopower was fabricated via free-radical polymerization. The HTIG exhibited high thermopower, sensitive fire warning and strain sensing, excellent flame retardancy and self-adhesive performance. The thermopower of the HTIG was as high as 3.04 mV K⁻¹, which was tens of times higher than those of traditional electronic thermoelectric materials, and it showed a good linear relationship between the voltage and temperature difference. When being burned, the HTIG triggered the fire alarm in about 4 s and generated a voltage of more than 100 mV. More importantly, the HTIG showed high fire safety. It was quickly self-extinguished when removed from the fire. It increased the limiting oxygen index (LOI) of wood from 27% to more than 80%. Besides, the HTIG displayed good strain sensing performance, which could be used for motion monitoring. Our work provided new insights for the preparation of the next generation of intelligent multifunctional fireproof materials.