Construction of layer-by-layer assembled chitosan/titanate nanotubes based nanocoating on cotton fabrics: flame retardant performance and combustion behavior

A flame retardant nanocoating made from chitosan and titanate nanotubes was deposited on the surface of cotton fabric by the layer by layer assembly to improve its flame retardancy. Firstly, the hydrothermal method was used to prepare titanate nanotubes. Then, coated cotton fabrics were prepared by alternately submersing cotton fabrics into chitosan solution and titanate nanotube suspension. The structure of nanocoating on cotton fabric surface was tailored by altering number of bilayers and the concentration of titanate nanotube suspension. X-ray photoelectron spectroscopy confirmed that titanate nanotube filled nanocoating was successfully deposited on the surface of cotton fabric. Furthermore, the titanate nanotubes assembled a randomly oriented and entangled network structure, as can be observed by scanning electron microscopy. The thermogravimetric analysis result indicated that the thermal and thermal-oxidation stability of all coated cotton fabrics were both improved in the high temperature range from 330 to 700 °C. The microscale combustion calorimeter result showed that all coated cotton fabrics have the reduction in peak heat release rate and total heat release compared with that of pristine cotton fabric. Moreover, the reduction was dependent on the concentration of titanate nanotube suspension and number of bilayers. The improved flame retardancy can be ascribed to the protective effect of the titanate nanotube network structure formed, which acts as a physical barrier to retard the heat, oxygen and mass transfers between the flame and underlying material.