Nacre-inspired intumescent flame retardant bridging network for intelligent fire warning and prevention

MXene has proved a bright prospect for developing intelligent fire-warning sensors, which is an emerging field but suffers from poor thermal oxidation stability and low flame retardant efficiency. Herein, a nacre-inspired bridging network constructed by MXene and chitin nanocrystals (ChNCs) with early fire-warning and high fire prevention was fabricated through low-temperature evaporation assembly approach. When encountering a fire source, such insulated network can independently construct a conductive path and then trigger the fire-warning signal owing to the char-forming and bridging effect of ChNCs. Typically, the ChMXene network incorporated with 30 wt% of adenosine triphosphate (ATP) (ChMXene-30) exhibits an ultrafast fire alarm signal of only 0.78 s and an ideal response time of 290 s. The thermal oxidation resistance, insulation performance and fire protecting properties of the network were drastically enhanced by the synergistic intumescent flame retardant effect of ChNCs and ATP. The corresponding enhancement mechanism was ascribed to the quenching effect of phosphorus-based radicals and diluting effect of non-combustible gases in the gas phase, the barrier effect of intumescent char layers as well as the effect of blowing-out fire in the condensed phase. This work offers a novel strategy to achieving sensitive fire-warning and reliable thermal oxidation resistance of MXene network for protection applications in disparate major fire potential and related hazardous environments.