Chemical warfare agents (CWAs) can currently not be degraded by materials designed for protecting soldiers against them. The carbon-based materials can only adsorb hazardous compounds.
In new research conducted by researchers in Gregory Parsons’ group at NC State, and co-workers at RTI International and the Edgewood Chemical Biological Center, material made from nanoscale fibers was coated with metal-organic frameworks (MOFs). The MOFs break down the CWAs, rendering them harmless. The MOFs form unique kebab-like structures when uniform coatings is synthesized on top of the nanofibers.
Junjie Zhao, a former Ph.D. student at North Carolina State University and lead author of a paper on the work, stated that they have been successful in achieving their goal of developing new materials that can detoxify CWA compounds. He added that earlier research had already found that MOFs could be effective at degrading CWAs. As MOFs normally come in powder form, the team wanted to see if they could grow MOFs as functional coatings onto fibers. If this were possible, the MOFs could be used in protective garments, masks and filters.
Parsons, an Alcoa Professor of Chemical and Biomolecular Engineering at NC State, believes that the feasibility of controlled MOF thin films that retain their chemical functionality is an important step for personal security. He adds that apart from the obvious military uses, the study has implications for many other commercial and civilian uses.
Using a vapor phase technology called atomic layer deposition, a thin film of titanium oxide is deposited onto a nanofiber material. A nucleation layer is formed by the titanium oxide, enabling the researchers to apply an even distribution of several zirconium-based MOFs onto the nanofibers. Zhao notes that the MOFs uniformly cover the entire nanofiber structure, much like meatballs on a skewer.
The MOF functionalized fabric was tested with the nerve agent soman and a CWA simulant. The half-life of the soman was reduced to as short as 2.3 minutes when exposed to the nano fabric, while the half-life of the CWA simulant was as short as 7.3 minutes.
Christopher Oldham, a senior research scholar at NC State and co-author of this paper, reckons the field of materials designed for CWA protection has taken a big step forward with these results. The subsequent steps will include evaluating the durability of the materials in various conditions and integrating the MOF-nanofiber structures into garment and suit materials that are currently being used in the field.
Current field chemical suits are heavy and soldiers wearing them require a lot of energy. If the MOF-coated nanofibers can be integrated into outer layers of the existing chemical suits, it may be possible to remove some of the inner layers of the suit. This could eventually transform the suits to behave and feel less like a garbage bag and more like athletic wear.
The paper is published in the journal Angewandte Chemie International Edition.