Synthesis of novel Si–P–N complex coating for the fabrication of flame-retardant and hydrophobic cotton textile potentially suitable for rail seat cover

In this study, we fabricated a fancy cotton textile with sustained flame retardancy and hydrophobicity by dip coating the fabric with two complex solutions (CS). Solutions A and B consisted of chitosan, urea, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane, which were rich in silica (Si), phosphate (P), and amide (N). The chemical interaction and surface morphology of the CS coated on the textile were verified by Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDX) spectrometry. Thermogravimetric analysis, differential scanning calorimetry, an ASTM D6413 vertical flame test, and cone-calorimeter test were conducted to study the thermal and flame-retardant properties. The IR spectral peaks at 730, 820, and 1540 cm−1 are the main evidence for chemical interaction, and a uniform distribution can be seen in the SEM-EDX analysis. The thermal stability was significantly enhanced by producing char from 6.7 to 33.5 % at 700 °C. Surprisingly, the cotton textile exhibited self-extinguishing behavior. This was evidenced by the shortened burning length from 300 to 84 mm during 12 s of flame exposure in the VF test, as well as reductions in the peak heat-release rate and total heat release rate from 203 to 21 kW/m2 and from 20.1 to 2.8 MJ/m2, respectively. The hydrophobicity of the textile increased upon application of the CS coating, with a contact angle (CA) of 127°. Practical examination confirmed that the treated fabric was well suited for seat upholstery.