Biomimetic and environmentally friendly self-assembly behavior of melamine onto the surface of black phosphorus nanosheets: Constructing advanced P/N-containing nano flame retardants

Abstract

Herein, inspired by the hierarchical structure within the biological protein, we adjust the temperature of the aqueous solution to control the unfolding and reconstitution of hydrogen bonds among melamine (MA) molecules, thus preparing MA-functionalized black phosphorus (MA@BP) nanosheets. As confirmed by the first-principles calculations, melamine can spontaneously adsorb onto the surface of BP nanosheets and enhance the interfacial interactions between BP nanosheets and thermoplastic polyurethane (TPU) matrix. Compared to pure BP nanosheets, MA@BP nanosheets present more efficient suppression effects in heat release and toxic CO production. Besides, due to the photo-thermal conversion effect of BP nanosheets, TPU-MA@BP-2.0 presents an equilibrium temperature of ∼ 80 °C under simulated sunlight of 1.0 kW/m2 and a significant solar de-icing performance. The solve-free and hydrogen-bond assembly method not only solves the lack problem of functional groups for the functionalization of BP nanosheets, but also develops a flame-retardant and photo-thermal polymer nanocomposite applied in various occasions.