Hypophosphorous acid cross-linked layer-by-layer assembly of green polyelectrolytes on polyester-cotton blend fabrics for durable flame-retardant treatment

In this work, a facile method to manufacture the layer-by-layer (LbL) assembled coating with durable flame-resistant effect on the polyester-cotton blend fabrics was reported. The LbL coating modified polyester-cotton fabric was treated with positively charged polyethyleneimine (PEI) and negatively charged oxidized sodium alginate (OSA) successively. Subsequently, the PEI/OSA coating was cross-linked by hypophosphorous acid (HA). As characterized by X-ray photoelectron spectroscopy and scanning electron microscopy, the HA cross-linked PEI/OSA coatings were successfully deposited on the surfaces of polyester and cotton fibers. Effects of the as-prepared coating on thermal stability, flame retardancy and laundering durability of the polyester-cotton blend fabrics were investigated. Thermogravimetric analysis revealed that the thermal decomposition of modified polyester-cotton fabric could be retarded obviously compared with the untreated one, as evidenced by the improvement in the 5% mass loss temperature by 30 °C. In the horizontal burning test, self-extinguishing behavior could be achieved for the polyester-cotton fabric treated with 5 bilayers coating. Moreover, the 77% and 75% reduction in the peak heat release rate and total heat release were observed for the polyester-cotton fabric treated with 10 bilayers coating. The treated fabrics still showed good flame retardant performance after 12 laundering cycles.