The development of phosphorus-doped hybrid silica sol coating for silk with durable flame retardancy

The fabrication of phosphorus-doped sol-gel coatings for durable flame retardant (FR) modification of textiles are of interest. This study facilely synthesized a novel phosphorus-doped silica sol system using 3-aminopropyltriethoxysilane, glutaraldehyde, diethyl phosphite by simultaneous Kabachnik-Fields and sol-gel reactions. The morphology and chemical structures of hybrid silica particles were studied by TEM, FT-IR and NMR. Then, the hybrid silica sol was applied as durable FR coating to reduce the flammability of silk. The FR property and washing durability, smoke and heat generation capacity, thermal stability, and FR mechanism of coated silk fabrics were explored. The hybrid silica coating displayed good FR performance because of the synergistic action among Si, P and N. The coated fabrics self-extinguished after 25 launderings and had a high LOI value of 28.0% thanks to the covalent grafting of hybrid silica coating on silk fabrics. The explorations on silk residues confirmed the intumescent FR mechanism of coated silk. The hybrid silica coating is promising to functional as feasible and durable FR strategy for silk fabric.