Mechanically robust and multifunctional polyimide/MXene composite aerogel for smart fire protection

Multifunctional smart fire-protection aerogels are urgently needed to meet the requirement of the Internet of Everything era. Herein, we fabricated a mechanically robust and high fire-safe polyimide/MXene composite aerogel (denoted as PI@MXene) with sensitive temperature-sensing and fire-warning capability. Thanks to the unique thermoelectric effect and high electrical conductivity of the 2D transition metal carbide (MXene) nanosheet, PI@MXene exhibited a linear relationship between the thermoelectric voltage and the temperature difference, showing sensitive temperature-sensing capability. When being burned, it could repeatedly trigger the fire-warning system in less than 5 s. More importantly, owing to the lamellar barrier and skeleton supporting effect of the MXene nanosheets, PI@MXene exhibited excellent flame retardancy, which self-extinguished within 1 s after exposing to a flame for 60 s and whose peak heat release rate was significantly decreased by 78% compared with PI aerogel. Besides, PI@MXene showed impressive thermal insulation, outstanding thermostability and durable piezoresistive sensing. This work provides a novel strategy to fabricate next-generation multifunctional fireproof aerogel, showing promising applications in intelligent robots, aerospace, and railway transportation.