Textile Flame Retardancy Through Surface Engineering: Advances

Flammability of textiles is a surface-confined phenomenon: undoubtedly, the textile surface, which is the most critical area, controls the mass and heat transfers, accountable for fueling the flame, from and to the surroundings. Consequently, the physico-chemical features of the textile surface play a crucial role in favoring or preventing the ignition and combustion processes. When the textile is not inherently flame retarded, it is possible to modify its surface in order to make it flame retarded. More specifically, it is possible to exploit surface engineered strategies in order to significantly modify (and improve) the fire performance of textile materials: in fact, tailoring their surface by depositing designed on purpose coatings allows slowing down the heat and mass transfer phenomena occurring during the fire stages, hence enhancing the fire behavior of the treated substrates. Among the different surface engineering strategies, sol-gel and layer-by-layer approaches have clearly demonstrated their suitability in fire retardancy of natural and synthetic textiles: this paper is aimed at reviewing the current state of the art related to the design of fully inorganic, hybrid organic-inorganic, or intumescent flame-retardant coatings on different fabric substrates (namely, cotton, polyester, and cotton-polyester blends). The potential progresses and the existing limitations of these approaches are also discussed.