Fabrication of liquid and vapor protective cotton fabrics.

Through microwave-assisted techniques, cotton textiles treated with heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane in the presence of high surface area silica nanoparticles create a material capable of repelling bulk liquid challenges while simultaneously adsorbing organic vapors from bulk liquid droplets. Characterizing the contradictory behavior of adsorption of vapors and repellency of liquids is the primary focus of this article. These procedures reveal a quick and simple method for a one-step deposition of a vapor-sorptive, liquid-repellent, Cassie-Baxter surface onto textiles. Packed column breakthrough and single swatch permeation experiments showed that treated materials possess a high affinity for 3-hepten-2-one vapor, while goniometry revealed contact angles in excess of 120° for surface-deposited, 5 µL droplets of several test liquids. Scanning electron micrograph images confirm a lotus-like, nanorough surface, while ATR-FTIR spectra confirm surface fluorocarbon moieties. The performance of so-treated materials lends itself to the application of chemical protective apparel, while the simplicity of the treatment bodes well for potential commercialization.

Methyl salicylate: a reactive chemical warfare agent surrogate to detect reaction with hypochlorite.

Methyl salicylate (MeS) has a rich history as an inert physical simulant for the chemical warfare agents sulfur mustard and soman, where it is used extensively for liquid- and vapor-permeation testing. Here we demonstrate possible utility of MeS as a reactivity simulant for chlorine-based decontaminants. In these experiments MeS was reacted with sodium hypochlorite varying stoichiometry, temperature, reaction time, and pH. No colored oxidation products were observed; however, chlorination of the aromatic ring occurred ortho (methyl 3-chlorosalicylate) and para (methyl 5-chlorosalicylate) to the position bearing the -OH group in both the mono- and disubstituted forms. The monosubstituted para product accumulated initially, and the ortho and 3,5-dichloro products formed over the next several hours. Yields from reactions conducted below pH 11 declined rapidly with decreasing pH. Reactions run at 40 °C produced predominantly para substitution, while those run at 0 °C produced lower yields of ortho- and para-substituted products. Reactions were also carried out on textile substrates of cotton, 50/50 nylon-cotton, and a meta aramid. The textile data broadly reproduced reaction times and stoichiometry observed in the liquid phase, but are complicated by physical and possibly chemical interactions with the fabric. These data indicate that, for hypochlorite-containing neutralizing agents operating at strongly alkaline pH, one can expect MeS to react stoichiometrically with the hypochlorite it encounters. This suggests utility of MeS in lieu of such highly hazardous surrogates as monochloroalkyl sulfides as a simulant for threat scenarios involving the stoichiometric decomposition of sulfur mustard. Specifically, the extent of coverage of the simulant on a fabric by the neutralizing agent can be directly measured. Similar reactivity toward other halogen oxidizing agents is likely but remains to be demonstrated.