Universal intumescent polyelectrolyte complex treatment for cotton, polyester, and blends

Inhibiting the flammability of natural, synthetic, and blended textiles with a single treatment is challenging because of differing fiber properties and chemistries. Intumescent surface treatments that promote char formation can be applied in the form of a polyelectrolyte complex (PEC) containing nitrogen and phosphorus compounds that combat burning in both the condensed and gas phase. Poly(allylamine hydrochloride) (PAH) and poly(sodium phosphate) (PSP) comprise a PEC that reduces the flammability of cotton, polyester, and polyester/cotton (PECO). The incorporation of melamine renders each substrate self-extinguishing. The degradation of PAH is seen to differ between substrates, with gas phase degradation being more prevalent on polyester and heterocyclization occurring on cellulose. Quantitatively, cotton flammability is reduced more than that of polyester, but significant improvements are made to the char yield, heat release, and volatile emission for all fabric types. This water-based coating is rapidly applied in two steps for fire protection. These results demonstrate the versatility of PEC coatings as environmentally-benign fire protection for a variety of chemistries.