Double-layered low-smoke and durable flame-retardant coating for cotton fabrics

Cotton fabrics are highly flammable, significantly hampering their availabilities and even leading to unacceptable adverse consequences. Flame-retardant coating is deemed to be the most promising strategy to overcome this problem. In this work, a double-layered ammonium alginate/phytic acid@trimethoxy(octyl)silane (AA/PA@TMOS) flame-retardant coating for cotton fabrics was developed. The AA layer protected the cotton fabric from PA to preserve the robustness of the cotton fabric and assisted PA in generating a stable and dense char layer, while the PA@TMOS layer inherited both flame retardancy and wash durability of their ingredients. Consequently, the AA/PA@TMOS-C achieved a high limiting oxygen index of 38.7% and low peak smoke produce rate of 0.0014 m2/s, demonstrating low-smoke flame retardancy. Even after 12 laundering cycles, the developed AA/PA@TMOS-C still showed incombustibility in air. The integration of extraordinary flame retardancy, smoke suppression and durability on the developed double-layered coating rendered its promising potential as a compelling flame-retardant coating for cotton fabrics or other materials.