An environmentally-friendly sandwich-like structured nanocoating system for wash durable, flame retardant, and hydrophobic cotton fabrics

Surface modification is a main approach for natural polymers to gain flame retardancy. Developing a green coating system to endow natural polymers with flame retardancy and wash-durability is extremely challenging. Herein, a sandwich-like structured nanocoating system with mutual restricted network through electrostatic interaction, hydrogen bonding, and chemical bonding were designed via multi-layered coating and UV curing. The coated natural cotton fabrics demonstrated exellent flame retardancy, wash durability, and hydrophobicity. The chemicals involved include montmorillonite (MMT), ammonium polyphosphate (APP), acrylated polyurethane (PU), branched polyethylenimine (bPEI), and polydimethylsiloxane (PDMS). The concentration of bPEI governed the wash durability of the coated fabrics, and those samples with a higher concentration of bPEI possessed better wash durability. Meanwhile, bPEI served as a flammable resource to deteriorate the flame retardant performance. The systematic evaluations of the coated fabrics after washing demonstrated that this coating system can maintain balanced wash durability and flame retardancy. Graphic abstract