Durable functional modification of silk fabric with reactive P/N/S-containing flame retardant

Improving flame retardancy of silk fabric will expand its potential application fields. Herein, a novel P/N/S-containing flame retardant (FR) named glutaraldehyde ammonium sulfamate diethyl phosphate salt (GASDP) was prepared by one-pot reaction among glutaraldehyde, ammonium sulfamate and diethyl phosphite. We further explored its potential applications in durable FR modification of silk fabric through textile exhaustion approach. The grafting mechanism, thermal stability, flame retardancy and washing durability, and FR mechanism of the coated silk fabrics were studied. GASDP coating showed high FR functional efficiency due to the synergism among P, N and S. The coated silk fabric covalently grafted by GASDP had a high LOI of about 30.0%; it still reached B1 classification after 25 washing cycles. GASDP coating exerted good flame retardancy to silk fabric through the intumescent FR mechanism. GASDP coating displays great potential to functional as efficient and durable approach to improve flame retardancy of silk fabric.