Few layer deposition and sol-gel finishing of organic-inorganic compounds for improved flame retardant and hydrophilic properties of polyamide 66 textiles: A hybrid approach

A hybrid methodology, including a few layer deposition of bio-based polyelectrolytes, chitosan (CS) and phytic acid (PA), along with a sol-gel treatment from (3-Aminopropyl) triethoxysilane (APTES) and boron doped APTES sol solutions, was followed in constructing a flame retardant and hydrophilic coating onto polyamide 66 (PA66) fabric surfaces. Layer by layer (LbL) assembled and simultaneously sol-gel treated PA66 fabric samples (i.e., PA66-5BL-APTES and PA66-5BL-B-d-APTES) could be able to stop the melt-dripping in vertical burning test. The boron doped APTES sol treated fabric samples with a 2-5 bi-layers deposition showed a reduced peak heat release rate (pHRR) (i.e., 22-30 % reduction) in cone calorimetry test and revealed improved thermal stability in thermogravimetric analysis test. More interestingly, the boron doped silica sol could boost up the hydrophilicity of the treated fabrics significantly compared to only LbL and simultaneously LbL deposited and silica sol treated fabric samples. Furthermore, only the 5 bi-layers deposited and concurrently sol-gel treated fabric samples exhibited durable flame retardant behavior after laundering.