Flame retardancy of polyester fabrics treated by spray-assisted layer-by-layer silica architectures

Silica-based architectures have been assembled through the layer-by-layer (LbL) technique on polyester fabrics by horizontal spray in order to enhance their flame retardancy properties. In particular, five bilayers of oppositely charged silica nanoparticles (namely, alumina-coated silica nanoparticles - positive counterpart - and unmodified silica - negative counterpart) have been employed as a model architecture, aiming to compare the performances achieved with spray-assisted layer-by-layer assembly with conventional dipping. Scanning electron microscopy has shown a better continuous coverage and a more homogeneous distribution of the silica coating, when assembled through horizontal spray compared to dipping. As a consequence, the LbL coatings deposited by spray have exhibited the most efficient protection for PET fabrics, blocking the dripping during the vertical flammability tests, increasing the time to ignition, and reducing the total heat evolved and its rate during combustion, as well as the total smoke release, CO yield, and CO2 yield.