Hierarchical boric acid/melamine aerogel based on reversible hydrogen bonds with robust fire resistance, thermal insulation and recycling properties

A Boric acid/Melamine aerogel (BM aerogel) with robust flame retardancy and thermal insulation was fabricated by a facial green route based on fully reversible hydrogen bonds using melamine and boric acid as precursors. The resulting BM aerogel possesses a hierarchical fibril structure and exhibits both intrinsic flame retardant and thermal insulation properties. The BM aerogel cannot be ignited at an oxygen concentration of as high as 80%. The superior performance together with the simple preparation process provides some new insight into the construction of a two-component molecular aerogel that is based on hydrogen bonds. Furthermore, owning to the full hydrogen bonding between melamine and boric acid molecules, the synthesized BM aerogel demonstrates typical thermal reversibility in water, which opens the door to the recycling of aerogel.