Fabrication of eco-friendly flame-retardant and hydrophobic coating for cotton fabric

Due to the flammability and easy mildew-prone nature of cotton fabrics, their application prospects are greatly restricted, particularly in clothing and household goods. With the goal of improving their application capabilities and aligning them with the current market requirements, we developed a green halogen-free coating that was both fire resistant and hydrophobic. In this study, a layer-by-layer self-assembly method was used to coat the cotton fabric surface with biomass tannin (TA) and phytic acid (PA) for flame-retardant modification, and then joined the monolayer polydimethylsiloxane (PDMS) for hydrophobic properties. The TA-2% PA-PDMS modified cotton fabric showed significant self-extinguishing property and intact carbon layers, while the TA-8% PA-PDMS modified cotton fabric showed a limiting oxygen index of 32%. More importantly, the TA-8%PA-PDMS cotton fabric still demonstrated excellent self-extinguishing properties after 40 laundering cycles. In comparison with pure cotton fabric, the total heat release and smoke release values of TA-8% PA-PDMS modified cotton fabric were reduced by 49.5% and 46.7%, respectively. Additionally, the PDMS conferred a certain hydrophobic property to cotton fabric (106°). A study of residual carbon evidenced that PA and TA associated with silica sources contributed to the formation of the P/N/Si hybrid char layer, which displayed a prominent condensed flame-retardant mechanism. This method brings up a new perspective for the construction of cotton fabrics that are hydrophobic and flame-retardant in the future.