▎ 摘　　要

NOVELTY - Reversible fire warning composite aerogel, prepared by self-assembling into a 3D structure by magnetic graphene oxide nanosheet, expanded graphite nanosheet and biomass matrix through intermolecular hydrogen bond cross-linking, and then freeze-drying. The magnetic graphene oxide nanosheets are magnetic iron oxide nanoparticle modified graphene oxide nanosheets. The expanded graphite nanosheets can instantly expand in volume by 100-250 times when exposed to high temperature, changing from flakes to worms, forming a good thermal insulation layer. The biomass matrix is carboxymethyl chitosan, hydroxypropyl chitosan, hydroxypropyl methylcellulose, cellulose nanofiber and/or sodium alginate. USE - The composite aerogel is useful in the fields of high-rise building fire alarm, flame retardant, heat insulation, and fire protection (claimed). ADVANTAGE - The aerogel: can break through the limit of single temperature monitoring, which can be used as a anode friction material to construct a triboelectric nanogenerator to realize self-power supply in the early warning process and can further improve its fire safety performance and broaden its application. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: preparing reversible fire early warning composite aerogel comprising (1) using reaction grafting magnetic iron oxide nano-particle or co-precipitation in-situ growing magnetic Iron oxide nanoparticle with functional groups to obtain the magnetized graphene oxide-sheet, where the method for grafting magnetic Iron oxide nano-particles by using functional group is: performing amino modification on the surface of the existing magnetic Iron oxide nanoparticle by silane ligand exchange, using magnetic Iron oxide nano-particle and graphene oxide carboxy functional group of the nano-sheet to realize magnetization modification to obtain the magnetic oxide nano graphene sheet, the size of the magnetic Iron oxide nano particle is 10-200 nm, the coprecipitation in-situ growing magnetic Iron oxide nanoparticle method is: adding the precursor of iron (II) and iron ( III) ions in the graphene dispersion liquid, co-precipitating in-situ generating magnetic oxide graphene sheet through alkaline catalysis, under the heating condition and (2) adding 1.12-17.65 wt.% expanded graphite nano-sheet and 11.2-176.5 wt.% biomass matrix aqueous solution at 38-42 KHz and 22-28℃, where the mass ratio of the magnetic graphene oxide sheet and expanded graphite nano sheet is (20-5):1, carrying out ultrasonic dispersion for 0.5-1 hours, using molecular hydrogen bond induced self-assembly to realize three dimensional network structure construction, aging for 2-6 hours, freezing and drying at -20 to (-80)℃ for 12-24 hours and preparing to obtain the reversible fire early warning composite aerogel; and use method of the reversible fire early warning composite aerogel comprising using the magnetic Iron oxide nano-particle with reversible resistance-temperature response as fire early warning function body and single heat reduction and multi-heat conduction characteristics of the graphene oxide nano sheet as the carrier of the iron oxide, where the synergistic effect breaks through the single temperature monitoring limit, under the normal state, the reversible fire early warning composite gas gel not trigger the fire early warning and lighting early warning lamp, when the first time is fire or receiving high temperature, reducing the magnetic Iron oxide nano-particle resistance, the graphene oxide nanosheets remove functional groups due to thermal reduction and the resistance is sharply reduced, so that the resistance and current change in the closed circuit is obviously so as to trigger early warning and/or lighting the early warning lamp, when the Nth fire and receiving high temperature, where N is ≥ 2, the magnetic Iron oxide nanoparticle resistance is reversible reduction of the old resistance, and the graphene sheet only provides a conductive path of continuous electrons, then assisting the magnetic Iron oxide nano-particles to realize repeated fire early warning and/or lighting the warning lamp.