Spider web-inspired multifunctional compound for durable fire safety, smoke suppression and enhanced strength cotton fabrics

Flame retardants with outstanding flame resistance and durability, addressing the issues of excessive smoke and weakened strength found in traditional phosphorus-based flame retardants for cotton, and offering benefits such as high char yield, low smoke emission, formaldehyde-free composition, and enhanced fabric strength, represent the future direction of eco-friendly flame retardants for cotton textiles. This study reports a durable/enhanced/smoke suppressing flame retardant system with multiple flame retardant elements. A phosphorus‑nitrogen‑boron flame retardant (TCPA) was successfully synthesized from melamine, phosphoric acid, and a boron spiro ring. Its LOI value can reach 49.0 ± 0.2 % and THR has been reduced by 61.9 % compared to cotton. After 50 washings, its LOI value can still reach 38.8 %. This flame retardant is rich in boron and can form a continuous and uniform carbon layer during combustion, which greatly reduces the release of smoke. Additionally, by analyzing the pyrolysis products in both the gas and condensed phases, the pyrolysis process and flame-retardant mechanism of the treated cotton fabric were inferred, while the physical and mechanical properties of the flame-retardant cotton fabric were also examined. The results underscored the advantages and potential of this flame retardant system, demonstrating efficient flame retardancy, low smoke emission, and preservation of the fabric's strength.