A Novel Green Approach for Enhancing Cotton Fabrics with Flame Retardant and Hydrophobic Properties via UV-Polymerized Poly (ionic liquid)

In this study, an innovative multifunctional coating for cotton fabrics via a straightforward UV-initiated polymerization method has been developed using a non-aqueous solvent. Synthesized from N-bromobutane, 1-vinylimidazole, potassium hexafluorophosphate (KPF₆), and sodium tetrafluoroborate (NaBF₄), the poly（ionic liquid） (PIL) imparts exceptional flame retardancy and hydrophobic properties to cotton fabrics. This PIL coating uniformly adheres to the cotton surface, significantly enhancing flame retardancy and durability. Notably, the PIL-PF₆-treated cotton achieved a high limiting oxygen index (LOI) of 39.5% and displayed a damaged length of approximately 94   mm in vertical flammability tests (VFT). Even after 20 washing cycles, the PIL-PF₆-treated fabric maintained a damaged length below 100   mm, highlighting its long-lasting effectiveness. This work offers a practical and effective strategy to enhance the safety and longevity of cotton fabrics, presenting promising applications in the field of flame-retardant textiles.