Biomacromolecules as novel green flame retardant systems for textiles: an overview

The field of flame retardancy for polymeric materials (i.e. plastics, foams and in particular textiles) is currently facing several changes and challenges because some of the current halogenated or phosphorus-based flame retardants (FRs) have proven to be persistent, bioaccumulative, carcinogenic and/or toxic for animals and humans. Thus, the search for highly efficient green flame retardant products, which are exploitable by using simple and environmentally-friendly techniques (i.e. impregnation/exhaustion, layer-by-layer), is driving the researchers towards the development of worthy alternatives. In this context, very recently, biomacromolecules (in particular proteins and deoxyribonucleic acid) have been thoroughly investigated because they exhibit significant potentials as novel green FRs for selected fabrics (cotton, polyester and their blends), as well as for bulk polymers (ethylene vinyl-acetate copolymers) and foamed polyurethane substrates. This work aims to review our recent results related to the "unconventional" use of these biomacromolecules as FRs with low-environmental impact for fabric substrates, as well as the challenges and the perspectives that these products may offer in the forthcoming years in the field of flame retardancy for textiles. To provide the basic knowledge necessary for understanding the role of biomacromolecules as FRs for textiles to the readers, first of all the description of the structure, main properties and conventional applications of proteins and deoxyribonucleic acid is provided; the thermal and thermo-oxidative stability, the reaction to a flame exposure or to an irradiative heat source of the selected fabrics - cotton, polyester and their blends - will be discussed, as well.