**5. Conclusions**

The flame retardant treatment of nylon textiles is getting constant development with time and becoming more sustainable in terms of uses of bio-derived flame retardant compounds and the green application processes. However, in the earlier applications, the use of petro-based flame retardant compounds has been more prominent. Additionally, it is seen that the fiber stage finishing has been more preferable over the topical finishing in the previous applications. Nonetheless, this fiber stage finishing still exists at a limited scale while some sort of modification is initiated in the current applications to convert this process more eco-friendly. However, due to the limitation of fiber stage finishing method related to the poor mechanical or physical properties in the modified fibers, the topical finishing has become very popular in today's applications. Meanwhile, the green practices in topical/surface finishing, especially in terms of flame retardant compounds and application methods are increasing day by day. These bio-derived compounds show efficacy in improving some crucial flame retardant parameters, namely reducing pHRR and enhancing the char yield % as their polyalcoholic aromatic structure favors the condensed phase mechanism. However, they are yet to show the potency in improving LOI values and thermal stability. Even in some extent, coatings developed from bio-derived polyelectrolytes via ionic interaction suffer from poor wash durability, which need to be optimized further. In line, some sort of hybridization, both in application methods (i.e., sol–gel/layer-by-layer assembly, etc.) and in flame retardant compounds (i.e., organic/inorganic/nanocompounds) have been enormously used in these days. In a typical application, flame retardant compounds belonging to organic species produce charring while the inorganic species offer shielding effect to these char residues to safeguard the underneath textiles from further burning. Such kind of hybridization has been found beneficial in improving the charring ability of nylon textiles as the nylon polymers show poor charring due to their typical aliphatic structures. Though some recent works have already shown promise in imparting flame retardant properties to the nylon textiles considering the environmental impacts and durability issues of such finishing methods, still there are challenges to imply them commercially.
