Evaporation Induced\nFlame Retardant Polyelectrolyte\nComplex for Cotton

Cotton is one of the most used textiles due to its comfort\nand\nbreathable nature, but it is extremely flammable. To reduce the flammability,\na polyelectrolyte complex coating composed of polyethylenimine (PEI)\nand sodium hexametaphosphate (PSP) is deposited in a single step.\nAmmonia is used as a volatile base that evaporates to reduce the pH\nand induces complexation on the cotton surface. Cotton coated with\na 1:2 molar ratio of PEI:PSP gains 28 wt % and reduces the total heat\nrelease by 93%, compared to neat cotton. The method of flame retardant\naction can be attributed to an effective intumescent coating. After\nfive water rinses, the coated cotton maintains its flame retardant\nbehavior, with only 7 wt % added to the textile, due to a more effective\nionically cross-linked network. This study demonstrates, for the first\ntime, an efficient and scalable evaporation induced polyelectrolyte\ncomplex coating that imparts self-extinguishing behavior to cotton\nand can be adapted for many other flammable materials.