Developing a novel UV protection process for cotton based on layer-by-layer self-assembly

A new approach for UV protection of cotton fabrics based on electrostatic self-assembly (ESA) technique was studied in this paper. Three fluorescent brightening agents (FBAs) and poly(diallyldimethylammonium chloride) (PDDA) were stepwisely fabricated on cationized cotton fabrics through direct layer-by-layer (LbL) deposition technique. Dyeing of the assembled cotton fabrics with anionic dyes shows regular and identifiable “odd–even” changes in color depth (K/S value), indicating the variation of surface polarities of the cotton substrates due to the alternate deposition of FBA and PDDA on them. The stepwise increases in UPF of treated cotton fabrics further revealed the growth of these LbL deposition multilayers. The assembled cotton fabrics could obtain excellent UV protection ratings of UPF > 40 after several bilayers of FBA/PDDA were fabricated, depending on the type of FBAs. Excellent durability to washing of the (FBA/PDDA)n multilayers was obtained, which indicates good adhesion between the multilayer coatings and the cotton surfaces.