An ultrasensitive fire-warning chitosan/montmorillonite/carbon nanotube composite aerogel with high fire-resistance

[Display omitted] •The aerogel achieved a hitherto shortest fire-warning response time (~0.25 s).•The aerogel self-extinguished and exhibited excellent flame retardancy.•The aerogel could resist a 1200 °C flame, showing outstanding thermal insulation.•The aerogel was endowed with good piezoresistivity. High fire-safe aerogel with multi-functionality is urgently desirable due to the frequent fire disasters. However, it is still a challenge to afford both excellent flame retardancy and sensitive fire-warning in combustible aerogels. Herein, we fabricated an ultrasensitive fire-warning and high fire-resistance chitosan/montmorillonite/carbon nanotube composite aerogel (CCA) via freeze-drying. Benefiting from the rapid decrease of the electrical resistance for amino-functionalized carbon nanotube when being burned, CCA achieved a hitherto shortest fire-warning response time (~0.25 s). Importantly, the aerogel exhibited excellent flame retardancy and self-extinguished in the vertical burning test. Besides, owing to the hierarchical porous structure of the aerogel and the excellent barrier effect of the montmorillonite nanosheet, CCA could resist a high-temperature flame up to 1200 °C and effectively prevent the temperature of the nonexposed side from increasing, exhibiting excellent thermal insulation. Furthermore, the mechanical resilience, anti-fatigue performance, electrical conductivity, and unique three-dimensional network endowed the aerogel with good piezoresistivity. This work provides a facile, environmentally-friendly, and cost-effective approach to fabricating multifunctional fire-safe aerogel, showing promising applications in exterior wall insulation, vehicle interior, firefighting, and wearable electronics.