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

Abstract

Deoxyribonucleic acid (DNA) has been mostly considered as a carrier of genetic information and gene expression. Recently, we have demonstrated that this biomacromolecule is very effective in providing cellulosic fabrics with flame retardant features, thanks to its intrinsic intumescent-like behaviour. Here, we have investigated the role played by different parameters on the overall flame retardant features: DNA molecular size, pH of the DNA aqueous solutions, and number of impregnations. For this purpose, herring DNA, at three different molecular sizes, low (100-200 base pairs, bp), medium (400-800 bp) and high (2000-10000 bp), has been selected as model biomacromolecule; its effect as fire protective coating on cotton fabrics has been assessed in terms of resistance to a flame application (through horizontal flame spread tests) and to an irradiative heat flux of 35kW/m 2 (by cone calorimetry). Furthermore, thermogravimetric analyses have been exploited for evaluating thermal and thermo-oxidative stability of the treated fabrics. *Manuscript Click here to view linked References 2The results clearly indicate that, despite a similar composition, the coatings containing low molecular size DNA exert a superior fire protection on the fabric substrate, as clearly indicated by horizontal flame spread and cone calorimetry tests. Multiple impregnation treatment turned out to be more performing than the single one, being equal the final add-on achieved. More specifically, the use of multiple impregnations at pH=4 and 8 allowed achieving self-extinction for 86 and 74%of the tested samples; in addition, 45 and 25% reductions of total heat release and heat release rate peak under 35 kW/m 2 have been found with respect to untreated cotton. These findings may be attributed to themorphology of the low molecular size DNA coating, which shows a greater penetration into the microfibrillar surfaces of the component fibres within the fabric and to its higher thermal stability in air.

Recent Advances for Flame Retardancy of Textiles Based on Phosphorus Chemistry

“…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 .…”

Nucleic acids from agro-industrial wastes: A green recovery method for fire retardant applications

“…FY was less effective than AY because of the higher molecular weight of extracted DNA (Bosco et al, 2015). Nevertheless, microfiltration probably caused a better homogenization of the extract and allowed the formation of a more protective coating, in comparison with unpurified FY-derived extract.…”

“…The good flame retardant properties of unpurified AY-derived extract are likely due to the high content of low molecular weight DNA (Fig. 4), which makes the biomacromolecule more effective in protecting the underlying fabric (Bosco et al, 2015).…”

“…by applying aqueous solutions/dispersions directly to different textiles, using traditional processes, such as impregnation/exhaustion and spraying). Recently, low molecular weight DNA was employed as an effective intumescent flame retardant coating for cotton fabrics, since it has demonstrated to provide self-extinction in horizontal flame spread tests and a substantial reduction in the heat release rate in cone calorimetry tests (Alongi et al, 2013;Bosco et al, 2015). The DNA's fire retardant activity has been ascribed to the simultaneous presence of phosphate groups, nitrogen bases and deoxyribose sugars in the same molecule, which makes the biomacromolecule to be considered as an intumescent-like product.…”

Research progress of bio-based polymer flame retardant coating

“…第一阶段为物理脱水, 脱去淀粉的结晶 水, 第二阶段在300℃开始进行化学脱水以及热分解, 此时羟基之间发生缩合形成醚并释放水, 同时在葡萄 图 3 (a) 10 s火焰测试后(样品从中间切割以显示内部未受 损材料(右)), 8 BL CS/蛭石涂覆PUF燃烧后数码照片(左); (b) 8 BL CH/VMT PUF燃烧后核心处SEM图像; (c) 8 BL CH/VMT PUF燃烧后炭层SEM图 [16] (网络版彩图) 图 4 (a) 不同pH值下涂层厚度, 图右为pH=4 (b), 6 (c)时10 BL下的AFM图像 [17] (网络版彩图) 香共轭环 [31] . 淀粉是一种天然阻燃材料, 并且其本身 图 5 次磷酸改性CS制备涂层工艺流程及涂层热稳定性、 阻燃性能测试结果 [25] (网络版彩图) [39] 、加热速率 [42] 、分子大小以及 pH值 [43] 对阻燃性能的影响, 并将其用于EVA、PP、 ABS、PET以及PA6 [44] .…”