Reactive phytate-based intumescent flame-retardant toward sustainable and durable functional coating of silk fabric

The development of reactive and natural phytate-based intumescent flame-retardant systems is helpful for fabricating sustainable and durable functional textiles. In this study, a novel and reactive intumescent flame-retardant (TPCE) was synthesized using phytic acid, triethanolamine and citric acid. The TPCE coating was then applied onto the surface of silk fabric through covalent grafting, resulting in an effective and durable functional silk fabric. The chemical structure of TPCE, the covalent coating action on the silk fabric surface, thermal degradation behavior, heat and smoke generation properties, flame-retardant performance and mode of action of coated silk fabrics were explored. The TPCE coating improved the thermal resistance and suppressed the potential heat and smoke production of silk. The coated silk fabrics exhibited self-extinguishing capacity, even after undergoing 30 washing cycles, suggesting excellent washing durability. The coated silk char residues had fibrous, phosphorus-rich, highly graphitized and better swelled features, which enabled coated silk fabrics to greatly increase fire safety. These findings suggested that the TPCE coating is promising for use as an efficient and reactive intumescent flame-retardant approach toward sustainable and durable functional modification of silk fabric.