A wash-durable polyelectrolyte complex that extinguishes flames on polyester-cotton fabric

Polyester-cotton (PECO) blends are widely used in the apparel industry due to their desirable combination of comfort and durability, but their high flammability remains a safety concern. Layer-by-layer (LbL) assembly has proven to be a powerful tool in reducing the flammability of textiles, although the high number of processing steps is a challenge. In an effort to produce nanocoatings similar to an existing LbL recipe, consisting of poly(allylamine) and a polyphosphate, deposition of a water-soluble polyelectrolyte complex (PEC) onto PECO fabric was investigated. Treatment of this one-step coating with an acidic buffer yields a water-insoluble nanocoating capable of extinguishing flames during vertical flame testing, outperforming a similar multilayer coating assembled layer-by-layer. Pyrolysis-combustion flow calorimetry revealed a total heat release reduction of 30% for PECO coated with 18 wt% PEC. The coated fabric also exhibited a 78% and 31% reduction in peak heat release for cotton and polyester, respectively. In addition to stopping fire, this coating is durable to five home laundering cycles (and eight hours in boiling water) without losing any flame retardant activity. Although microscopy revealed identical structures in LbL and PEC coatings, elemental analysis revealed a difference in composition. The PEC coating showed greater flame retardancy than layer-by-layer assembled coatings using the same ingredients, while also greatly reducing the number of processing steps, making this a promising treatment for large scale fabric protection.