Flame-Retardant Graphene Foam Fights Fire With Carbon

Halogenated flame-retardant materials have come under fire in recent years because of concerns they have negative health and environmental impacts. Knowing that graphene has worked well as a flame-retardant additive for polymers, researchers in China and the U.S. wondered if they could make a fire-resistant material composed primarily of the carbon allotrope. A team led by Liang­ti Qu of Beijing Institute of Technology and Liming Dai of Case Western Reserve University prepared an ultralight foam made of graphene and phosphorus oxide and phosphorus nitride nanoparticles (ACS Nano 2016, DOI: 10.1021/acsnano.5b06710). The scientists prepare the flame-retardant material by mixing a graphene oxide solution with hexachlorocyclotriphosphazene and turning the blend into foam via a freeze-drying process. This method, they note, has the advantages of being simple, scalable, and environmentally friendly. They then expose this material to a flame, which transforms the graphene oxide into graphene and eliminates chlorine from the material. The resulting foam outperformed flame-retardant polymers, metallic oxides, and metal hydroxides in tests. What’s more, the foam is a lightweight absorber of microwave radiation, which makes it promising as a radar-shielding material in commercial or military aircraft.