A self-healable and highly flame retardant TiO2@MXene/P, N-containing polyimine nanocomposite for dual-mode fire sensing

Scalable early fire warning sensors that integrate passive flame-retardant strategies and active fire alarm sensing are highly requirable in diverse areas. However, the single-mode fire response and performance degradation or even malfunction under mechanical damages remain key challenges for current early fire warning sensors. Herein, a self-healable and flame retardant TiO2@MXene/P, N-containing polyimine nanocomposite (TMPNP) is designed as repeatable dual-mode fire warning sensors. On the one hand, the TMPNP exhibits a high temperature coefficient of resistance of -2.21 %/celcius, which endows nanocomposite with an extraordinarily sensitive noncontacting fire warning performance; on the other hand, the TMPNP demonstrates outstanding fire contact warning features of responsive time being less than 1 s and repeatable alarming response, as well as excellent flame-retardant functionality of LOI reaching up to 32.0 %. Moreover, the TMPNP can be effectively recovered after 30 cutting-and-healing cycles with a healing efficiency of 89.3 % via dynamic imine bonds. Particularly, its flame retardancy and fire warning properties in contact/non-contact mode are well maintained after self-healing. These merits support the scalable assembly TMPNP onto cotton textile to develop a wireless household fire early warning sensor linked to the Internet of Things, contributing to construct fire-safety smart buildings. This work provides a scalable strategy for preparing healable sensitive fire warning sensors, opening up a new opportunity for the practical application of eliminating indoor fire hazards.