Flame-retardant polyester/cotton blend with phosphorus/nitrogen/silicon-containing nano-coating by layer-by-layer assembly

Polyester/cotton (T/C) blends are widely used in the textile industry owed to the combination of both advantages of cotton and polyester. However, T/C blends are highly flammable due to the well-known scaffolding effect of the melting polyester and non-melting cotton fibers. Herein, to reduce the flammability of T/C blends, a nano-coating containing phosphorus, nitrogen and silicon was designed and constructed by layer-by-layer assembly of colloidal silica and polyphosphates. It was confirmed that the homogeneous nano-coating was successfully deposited on the surface of T/C blends, regardless of different surface morphologies and chemical nature of the synthetic and in-artificial fibers. Encouragingly, with 15 bilayer nano-coatings (15.5% weight increased), the coated T/C blends achieved self-extinguishing and got away from scaffolding effect in vertical flame test, and showed a little delay of ignition and a strong decrease of heat release during cone calorimetry test, indicating excellent flame retardance of the treated fabrics. The nano-coating had both gaseous- and condensed-phase flame-retardant activity, which was further confirmed by the results of char analysis and thermogravimetric analysis/infrared spectrometry.