DNA: a novel, green, natural flame retardant and suppressant for cotton

Abstract

For the first time, deoxyribonucleic acid (DNA) from herring sperm has been employed as a novel flame retardant system for enhancing the thermal stability and flame retardant properties of cotton fabrics.Indeed, DNA could be considered an intrinsically intumescent flame retardant as it contains the three main components that are usually present in an intumescent formulation, namely: the phosphate groups, able to produce phosphoric acid, the deoxyribose units acting as a carbon source and blowing agents (upon heating a (poly)saccharide dehydrates forming char and releasing water) and the nitrogen-containing bases (guanine, adenine, thymine, and cytosine) that may release ammonia. The flammability tests in horizontal configuration have clearly shown that after two applications of a methane flame for 3 s, the DNA-treated cotton fabrics do not burn at all. Furthermore, when exposed to an irradiative heat flux of 35 kW m À2 , no ignition has been observed. Finally, an LOI value of 28% has been achieved for the treated fabrics as opposed to 18% of the untreated fabric.

Recent Advances for Flame Retardancy of Textiles Based on Phosphorus Chemistry

“…Similarly to other biomacromolecules, the presence of the coating strongly anticipated the cellulose decomposition, which was directly related to the DNA add-on: in particular, as assessed by TG analyses in nitrogen and air, the higher was the biomacromolecule add-on, the lower was the temperature, at which degradation started to occur. This finding was attributed to the phosphate groups of the biomacromolecule, which decompose at about 200 • C, releasing phosphoric acid, hence favoring the dehydration of the fabrics, and finally giving rise to the formation of a residue, thermally stable up to 500-600 • C [73,83]. Flammability tests performed in horizontal configuration clearly demonstrated that the self-extinction of the treated fabrics strictly depends on the biomacromolecule add-on: in particular, the fabrics having the lowest DNA add-on (i.e., 5 wt %) burnt completely, while the other specimens (having 10 or 19 wt % add-on) were able to achieve the flame out.…”

“…The structure of the obtained LbL assembly is schematized in Figure 30. biomacromolecule, which decompose at about 200 °C, releasing phosphoric acid, hence favoring the dehydration of the fabrics, and finally giving rise to the formation of a residue, thermally stable up to 500-600 °C [73,83]. Flammability tests performed in horizontal configuration clearly demonstrated that the self-extinction of the treated fabrics strictly depends on the biomacromolecule add-on: in particular, the fabrics having the lowest DNA add-on (i.e.…”

“…The use of DNA as a sustainable flame retardant is quite recent and can usually be attributed to the structure of this biomacromolecule, which represents an all-in-one intumescent system [73][74][75][81][82][83]. More specifically, the double helix comprises all three constituents of an intumescent material, namely: (i) the phosphate groups that form phosphoric acid; (ii) the deoxyribose units, which act as a carbon source and as blowing agents and (iii) the four nitrogen-containing bases that may give rise to the formation of NH 3 .…”

DNA coatings on cotton fabrics: Effect of molecular size and pH on flame retardancy

“…As a matter of fact, in previous reports, we have clearly demonstrated that this biomacromolecule is very effective in conferring flame retardant features to cellulosics [13,14]. In particular, in the first pioneering work [13]we have proved that the only application of low molecular size DNA from herring sperm to cotton fabrics (with a final 19 wt.-% dry add-on) by an impregnation/exhaustion method allows enhancing the thermal stability and flame retardant properties of cotton fabrics.…”

“…In particular, in the first pioneering work [13]we have proved that the only application of low molecular size DNA from herring sperm to cotton fabrics (with a final 19 wt.-% dry add-on) by an impregnation/exhaustion method allows enhancing the thermal stability and flame retardant properties of cotton fabrics.…”