BIOMACROMOLECULES/TITANIA NANOPARTICLES HYBRID COATINGS: A DURABLE FIRE RETARDANT STRATEGY FOR COTTON FABRICS

Cellulose-based materials almost exist in all aspects of everyday life and are essential to people’s everyday life. In fact, cotton is today the most frequently used textile fiber in the world. As a main component of cotton, cellulose is utilized for producing apparel, home furnishings and industrial products, despite its easy flammability, resulting in serious health risk and damage to textile products. As a consequence, flame retardant (FR) systems have been developed to reduce the combustibility of cotton textiles and the production of flammable decomposition products or toxic gases, thus limiting the overall risk of fire. Quite recently, a new strategy for designing flame retarded cotton fabrics was conceived, using selected biomacromolecules (namely, caseins, hydrophobins and whey proteins, as well as nucleic acids), which were applied by means of a pad-dry method to the underlying cellulosic substrate (1). Despite their effectiveness in slowing down the flame propagation or even, in the case of caseins and nucleic acids, to provide self-extinction to cotton fabrics, one of their main current limitations refers to their poor durability: in fact, the treated fabrics lose their flame retardant properties when subjected to washing cycles. In order to overcome this limitation, we have designed new hybrid flame retardant coatings based on TiO2 nanoparticles (NPs) and the selected biomacromolecules, exploiting both the intrinsic thermal resistance of the TiO2 ceramic phase and the strong affinity that titania NPs show towards the biomacromolecules and cotton substrates. This way, it was possible to improve the washing fastness of the resulting coatings, without affecting the overall flame retardant performances of the treated fabrics.