Constructing eco-friendly flame retardant coating on cotton fabrics by layer-by-layer self-assembly

A novel intumescent flame retardant (IFR) combination containing ammonium polyphosphate (APP)/ p - aminobenzene sulfonic acid modified melamine (AM)/Chitosan (CS) was coated on cotton fabric surfaces via layer-by-layer self-assembly. The fire performance, softness and bio-safety of the treated fabric were evaluated. Fabrics prepared with 15 self-assembly layers of AM-CS/APP had a limiting oxygen index value of 31.5%. Analysis of the cone calorimetry data revealed that the treated fabrics significantly suppressed heat release and mass loss. It was demonstrated that cotton fabrics exhibited a peak heat release rate (pHRR) value of 162.2 kW/m 2 and total heat release (THR) value of 17.7 MJ/m 2 , while the treated fabrics showed pHRR of 98.6 kW/m 2 and THR of 7.1 MJ/m 2 , dropped significant decrease of 40% and 60%, respectively. Furthermore, our results showed that only 8.1 wt% residue remained for the control cotton sample vs. 24.1 wt% for the treated after cone test. Cytotoxicity evaluation indicated bio-safety of the AM modified was much better than that of APP. In addition, the APP/AM/CS coating had minimal negative impact on the mechanical property of the resulting material. These result suggest cotton fabrics treatment proposed in this study provides a feasible way to produce environmentally friendly flame retardant cotton. Graphic abstract