Phosphorus-nitrogen-silicon-based assembly multilayer coating for the preparation of flame retardant and antimicrobial cotton fabric

A novel silicon- and nitrogen-containing compound, poly[3-(5,5-cyanuricacidpropyl)-siloxane-co-trimethyl ammoniumpropyl siloxane chloride] (PCQS) was synthesized and coated onto cotton fabrics with phytic acid (PA) by layer-by-layer assembly. The treated cotton fabrics were characterized by SEM, FT-IR and EDX. The thermal property, mechanical property, flame retardancy and antibacterial property of the coated cotton fabrics were investigated. The breaking strength of the coated cotton fabrics had a small decline. With the flame retardant effect of PCQS and PA, the coated cotton fabrics obtained excellent flame retardancy with LOI value of 29.8% and char length of 8.1 cm. Furthermore, the LOI value and char length of Cotton-PEI/(PCQS/PA)₃₀-Cl separately reached 28.5% and 7.9 cm and Cotton-PEI/(PCQS/PA)₃₀-Cl also showed high thermal stability with char yield of 34% at 600 °C, whereas pure cotton fabrics only obtained 8% char yield. The Cotton-PEI/(PCQS/PA)₃₀-Cl exhibited effective antimicrobial activity against E. coli O157:H7 and S. aureus with 100% bacterial reduction at 10⁶ CFU per square inch inoculated level within 1 min of contact time, respectively.