A multifunctional coating for cotton fabrics integrating superior performance of flame-retardant and self-cleaning

The development of cotton fabrics with flame-retardant and durable self-cleaning abilities is of considerable importance to practical application and economic values. In this work, a composite coating was designed using synthesized graphite carbon nitride (GCN) and phosphorylated chitosan (PCS) for cotton fabrics through a layer-by-layer self-assembled technique. The fabrics with four bilayers (G/PCS-4) exhibited low heat release (55.8% reduction compared with control cotton) and high limited oxygen index of 30.1% and achieved desired self-extinguishing with a damaged char length of 7.2 cm in vertical combustion test. This was manifested to benefit from the good performance of char-forming and efficient barrier action of the coating in which PCS catalyzed the cotton to form an expanded and stable char layer with the help of GCN. Moreover, the intensified adsorption capacity of PCS strengthened the photocatalytic activity of GCN on the surface. The degradation rate of the G/PCS-2 sample to rhodamine B can reach nearly 90% in 15 min. These coated fabrics also presented eminent and durable photodegradation capability for various organic compounds such as methylene blue and methyl orange, which can be utilized for self-cleaning for pollutants on the surface. This work opens a broad mind for the exploration for multi-functional textiles with flame retardant, self-cleaning, and even other functions in their application. Graphical abstract A composite coating which exhibits superior flame-retardant and self-cleaning performance was constructed on the surface of cotton fabrics.