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The toxicity of the most efficient fire retardant additives is a major problem for polymeric materials. Cellulose nanofiber (CNF)/clay nanocomposites, with unique brick-and-mortar structure and prepared by simple filtration, are characterized from the morphological point of view by scanning electron microscopy and X-ray diffraction. These nanocomposites have superior fire protection properties to other clay nanocomposites and fiber composites. The corresponding mechanisms are evaluated in terms of flammability (reaction to a flame) and cone calorimetry (exposure to heat flux). These two tests provide a wide spectrum characterization of fire protection properties in CNF/montmorrilonite (MTM) materials. The morphology of the collected residues after flammability testing is investigated. In addition, thermal and thermo-oxidative stability are evaluated by thermogravimetric analyses performed in inert (nitrogen) and oxidative (air) atmospheres. Physical and chemical mechanisms are identified and related to the unique nanostructure and its low thermal conductivity, high gas barrier properties and CNF/MTM interactions for char formation.

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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, layerby-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 fabricscotton, polyester and their blendswill be discussed, as well.

For the first time, polyester and polyester−cotton fabrics have been treated with an aqueous suspension of caseins to increase their thermal stability and flame retardancy. The effectiveness of the fabric treatment as well as the morphology of the deposited coatings have been assessed by infrared spectroscopy and scanning electron microscopy, respectively. The thermal stability of the treated fabrics in nitrogen and air, as well as their resistance to a flame application and to an irradiative heat flux of 35 kW/m 2 , has proven to be strongly affected by caseins. Indeed, in the case of polyester, a remarkable decrease of the burning rate (−70%) and a significant increase of its limiting oxygen index (from 21 to 26%) has been reached. In the case of polyester− cotton blends, caseins turned out to slow down the fabric burning rate (about −40%) and its resistance to an irradiative flux as assessed by cone calorimetry.