Ethanol-induced ammonium polyphosphate-silver gels paint: breaking the trade-off between conductivity, flame retardancy and adhesion in single-layer functional coatings

Electrical fires pose significant threats to the lives and property safety of people. Although utilizing coatings to impart conductivity and flame retardancy to materials is convenient and reliable, traditional layer-by-layer preparation methods have the limitations of cost, convenience and scalability. Therefore, a single-layer coating that simultaneously imparts excellent conductivity and flame retardancy to the materials presents broader application prospects. And good adhesion of the coating is another essential aspect. However, the trade-off between conductivity, flame retardancy, and adhesion creates huge challenges in the development of such coatings. Here, we report an ethanol-induced ammonium polyphosphate-silver (APP-Ag) gels paint to completely address the above issues. The high molecular weight APP served as both a flame retardant and an adhesive, while the coordinating action of phosphate groups ensured the effective dispersion of nanosilver, and the nitrogen-containing carbon layer formed from triethanolamine and ascorbic acid at high temperature significantly enhanced the conductivity of the coating by connecting the silver nanoparticles. The coated materials could achieve electrical conductivity of over 200 S/m, with limiting oxygen index (LOI) exceeding 60%. Meanwhile, the peak heat release rate (PHRR) and total heat release (THR) decreased by more than 30% compared to the untreated materials. Additionally, we utilized this gels paint to fabricate electric heating fabric, motion sensors, and fire alarm devices. Finally, we have thoroughly explored the potential mechanisms of conductivity, flame retardancy, and adhesion of the gel coatings.