As these seem to be the days of unethical warfare, one never knows what to expect. Explosives and guns are just the tip of the knife of terrorists who are willing to use whatever they have at hand to cause havoc and damage. Chemical weapons are certainly not off the table.
Perhaps in response to the possibility, or inevitability, of chemical attacks, researchers at North Carolina State University have created a fabric material containing nanoscale fibers capable of braking down chemical warfare agents (CWAs). The team synthesizes what they call uniform coatings of metal-organic frameworks (MOFs) on top of nanofibers. These form structures that look like meatballs on a skewer or shish kebabs. Essentially, it’s the MOFs that break down the CWAs and render them harmless.
Junjie Zhao, lead author of a paper on the work, points out that “Current technologies for addressing CWAs rely on carbon-based materials, but these carbon materials can only adsorb hazardous compounds, they can’t degrade them. Our goal was to develop new materials that can detoxify these CWA compounds, and we’ve been successful. Previous research found that MOFs can be effective at degrading CWAs. However, MOFs normally come in the form of a powder. We wanted to see if we could grow MOFs as functional coatings onto fibers, so that they could be used in masks, filters and protective garments.”
The process starts by depositing a thin film of titanium oxide onto a fabric made of nanoscale fibers using vapor-phase technology called atomic layer deposition. The titanium oxide serves as a nucleation layer, which enables the researchers to apply various zirconium-based MOFs onto the nanofibers in an evenly distributed way.
The MOF-functionalized fabric is then tested against both a CWA simulant and the nerve agent soman. The research team found that, when exposed to the nano-kebab fabric, the half-life of the CWA simulant was as brief as 7.3 minutes. The half-life of the soman was as short as 2.3 minutes.
A paper titled “Ultra-Fast Degradation of Chemical Warfare Agents Using MOF–Nanofiber Kebabs” is published in the journal Angewandte Chemie International Edition. Corresponding authors of the paper are Parsons and Gregory Peterson of the Edgewood Chemical Biological Center. The paper was co-authored by Dennis T. Lee, Heather F. Barton, and Ian R. Woodward of NC State; Robert Yaga and Howard Walls of RTI; and Morgan Hall of Edgewood. The work was done with support from Edgewood, under grant number W911SR-07-C-0075, and the U.S. Army Research Office, under grant number W911NF-13-1-0173.
ABSTRACT: “Ultra-Fast Degradation of Chemical Warfare Agents Using MOF–Nanofiber Kebabs”
Authors: Junjie Zhao, Dennis T. Lee, Heather F. Barton, Ian R. Woodward, Christopher J. Oldham, and Gregory N. Parsons, North Carolina State University; Robert W. Yaga and Howard J. Walls, RTI International; Morgan G. Hall and Gregory W. Peterson, Edgewood Chemical Biological Center
Published: Sept. 21, Angewandte Chemie International Edition
Abstract: The threat associated with chemical warfare agents (CWAs) motivates the development of new materials to provide enhanced protection with a reduced burden. Metal–organic frame-works (MOFs) have recently been shown as highly effective catalysts for detoxifying CWAs, but challenges still remain for integrating MOFs into functional filter media and/or protective garments. Herein, we report a series of MOF–nanofiber kebab structures for fast degradation of CWAs. We found TiO2 coatings deposited via atomic layer deposition (ALD) onto polyamide-6 nanofibers enable the formation of conformal Zr-based MOF thin films including UiO-66, UiO-66-NH2, and UiO-67. Cross-sectional TEM images show that these MOF crystals nucleate and grow directly on and around the nanofibers, with strong attachment to the substrates. These MOF-functionalized nanofibers exhibit excellent reactivity for detoxifying CWAs. The half-lives of a CWA simulant compound and nerve agent soman (GD) are as short as 7.3 min and 2.3 min, respectively. These results therefore provide the earliest report of MOF–nanofiber textile composites capable of ultra-fast degradation of CWAs.
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