Thermally induced fire early warning aerogel with efficient thermal isolation and flame-retardant properties

Due to the energy-saving demands in chemical industries and building fields, thermal isolation materials (TIMs) are widely used. The general exploitation of combustible TIMs calls for timely fire alerts as well as flame-retardant modifications. This work provides a novel paradigm to address the issues simultaneously by preparing a multifunctional aerogel via a facile and environmentally friendly freeze-drying method. With the doping of ammonium polyphosphate and graphene oxide (GO), cellulose nanofiber-based aerogel exhibits excellent thermal-isolating as well as flame-retardant properties. The composite aerogel displays flameless pyrolysis as well as increased residue char. A fire-warning detector is designed to reliably monitor the early fire. Based on the flame-induced electrical resistance transformation characteristic of GO, it endows the composite aerogel with an ultra-fast fire-response time of similar to 2.6 s and a durable alarm signal. The flame-retardant and fire-alarm mechanisms are concluded. Overall, these results suggest that this composite aerogel has an enticing prospect in chemical industries and high-rise buildings, which may lay the foundation for designing multifunctional TIMs. The modified aerogel broadens its application territory by intrinsic fire-alarm characteristics, which covers the deficiency of delaying reaction as well as restricted application scenarios in traditional fire detectors.