Flame retardant coating of wool fabric with phytic acid/polyethyleneimine polyelectrolyte complex

The one-step polyelectrolyte complex (PEC) deposition approach shows great potential and feasibility to prepare flame retardant (FR) textile materials. This study developed a water-soluble PEC system by using phytic acid (PA) and polyethyleneimine (PEI) at pH 1.5 to improve the flame retardancy of wool fabric. After being dipped in the PEC solution, the wool fabric was treated with the pH 4 buffer solution to form a water-insoluble coating on the fabric surface. The coated wool substrates had superior inflating ability during the thermal radiation and flammability tests, giving rise to the greatly suppressed heat and smoke generation performance, and increased FR efficiency of wool fabrics through an intumescent charring mechanism. The coated wool fabric with the PEC consisting of 15% PA and 15% PEI was still able to self-extinguish after 10 washing cycles, demonstrating its good FR ability and durability to washing. The appreciable washing durability of the coated wool could be attributed to the abilities of PA and PEI to combine with each other to form insoluble coating on wool fiber surface and to ionically and covalently cross-link with wool fiber.