## 1 Introduction
The salt rejection ability of membranes increased slightly with the incorporation of GONPs, while the water flux was found to be similar to that observed for the pristine membranes without graphene oxide nanoplatelets. In the latest works, [25] the layer-by-layer (LBL) deposition of chitosan/melamine/urea and phytic acid onto the acrylic acid-grafted polyamide fabrics, including a pad-dry-cure treatment with chitosan/graphene oxide nanocomposites, was considered to improve the hydrophilicity and durable flame retardancy. The obtained results indicated that these hybrid coatings could significantly improve the flame retardancy as the limiting oxygen index value went up to 25% from 18.5% and could completely stop the melt dripping where the fabric sample with two bilayer deposition and simultaneously treated with chitosan/graphene oxide nanocomposite achieved a V-1 rating. Moreover, a considerable improvement in the thermal stability and char yield was also realized in the thermogravimetric analysis test. Furthermore, the as-prepared hybrid coatings imparted better hydrophilicity as a two bilayer deposition along with a pad-dry-cure treatment by the chitosan/graphene oxide system could boost up the hydrophilicity of the treated fabrics further compared to the only two bilayer deposited fabric sample. In the work [26], also chitosan and phosphorylated chitosan were deposited onto the polyamide fabric surfaces along with poly-acrylate sodium, via one-pot and layer-by-layer assembly methods in preparing flame-retardant coatings. Subsequently, to stabilize the deposited coatings, some of the fabric samples were treated under UV irradiation, and additionally, a thermal treatment was also carried out for the remaining fabric samples. The LbL assembled fabrics showed a better homogeneity in the coating structure over the one-pot deposited fabrics than as appeared in scanning electron microscopy. Nonetheless, the LBL-treated fabric sample with a higher weight gain% exhibited a greater improvement in the limiting oxygen index, and a reduced peak heat release rate. Similarly, in Ref. [27], chitosan and phytic acid, along with a sol-gel treatment from (3-aminopropyl) triethoxysilane and boron-doped APTES sol solutions, was followed in constructing a flame-retardant and hydrophilic coating onto polyamide fabric surfaces. Layer-by-layer assembled and simultaneously sol-gel-treated PA fabric samples could be able to stop the melt-dripping in a vertical burning test. The boron-doped APTES sol-treated fabric samples with a 2-5 bilayer deposition showed a reduced peak heat release rate in the cone calorimetry test and revealed an improved thermal stability in the thermogravimetric analysis test. More interestingly, the boron-doped silica sol could significantly increase the hydrophilicity of the treated fabrics compared to only LBL and simultaneously LBL-deposited and silica sol-treated fabric samples. The obtained results reveal that the LBL technique can be successfully used to deposit coatings providing a better flame retardancy of the polyamide matrices [25; 26; 27; 28]. In this work, polyamide 6 nanocomposites with MMT were surface modified via the layer-by-layer deposition of copper and phosphorus compounds. The influence of the deposition technique on the thermal properties and flammability of the surface-modified hybrid materials was examined and discussed.