Mineralized black phosphorus @ silica nanofiber multi-scale enhanced hydrogel coating for fire protection of polyurethane foams

Hydrogel, as a multifunctional engineering material, has attracted much attention for its flame-retardant applications. However, the low thermal stability of hydrogel forms a weak protective layer with weak adhesion, which limits its application. Therefore, through careful design, we successfully combined calcium phosphate nanocrosslinked point, silica nanofiber networks, and black phosphorus sheets to construct a multiscale reinforcing body. This reinforcement not only significantly improves the overall strength of the material, but also imparts excellent fire resistance properties. Further, we combined this reinforcement with intrinsic flame-retardant precursors to construct a hydrogel with high fire resistance. This hydrogel coating not only effectively resists flame attacks, but also exhibits excellent mechanical properties, thus addressing the shortcomings of conventional hydrogel coatings in terms of fire resistance and mechanical properties. When used to coat RPUF materials, the hydrogel-coated RPUF composites showed a 23.6 % reduction in peak heat release rate (pHRR), a 45 % reduction in total smoke production (TSP), and a 27 s extension in time to ignition (TTI). The hydrogel coating was found to be effective in inhibiting the spread of fire. In addition, the molecularly designed intrinsic flame-retardant hydrogel coating has good adhesion to RPUF and other substrates, which is sufficient for practical applications. The coatings have sustained fire protection and are suitable for a range of flame-retardant applications. This innovative design provides new ideas and methods for developing high-performance flame-retardant hydrogel coatings.