When it comes to warfare, the idea that a good offense makes the best defense tends to be a tried and tested strategy. That idea may now be coming to protective clothing that guards against chemical agents. Instead of simply capturing the harmful chemicals, scientists have developed a fabric actively destroys them down, which may lead to improved protection for soldiers on the front line.
"Current technologies for addressing CWAs rely on carbon-based materials – but these carbon materials can only adsorb hazardous compounds, they can't degrade them," says Junjie Zhao, a former Ph.D. student at North Carolina State University (NC State) and lead author of the research. "Our goal was to develop new materials that can detoxify these CWA compounds, and we've been successful."
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Key to the breakthrough was the team's use of metal-organic frameworks (MOFs). These are porous structures with big surface areas that soak up gases like microscopic sponges, something that has seen used in electronic noses that detect nerve gases and a number of carbon-capture research projects. While MOFs have also shown potential in degrading chemical agents, integrating them into clothing has proven a challenge.
The NC State researchers found a way around this by first creating a fabric made up of nanoscale fibers. They then layered a thin film of titanium oxide onto the fabric. This coating in turn allowed MOFs based on zirconium to form on the nanofibers, in a similar way to how you might find pieces of meat skewered onto a stick.
"We found that the MOFs formed on the nanofibers in a kebab-like structure, with the MOFs uniformly covering the entire nanofibers, like meatballs on a skewer," Zhao says.
This kebab-like nanofabric was then put to the test against a chemical agent simulant and also the nerve agent soman. The team found that the half-life (the time required for the quantity to decrease by half) of the simulant was as short as 7.3 minutes, while the soman's half-life was as short as 2.3 minutes.
"The next steps include integration of the MOF-nanofiber kebab structures into currently fielded garment and suit materials, and evaluating the durability of the materials in various conditions," says Christopher Oldham, a senior research scholar at NC State and co-author of this paper. "Currently, field chemical suits are heavy and require a lot of energy for the soldier to wear. If we can integrate the MOF-coated nanfibers into outer layers of the chemical suit, inner layers of the suit might be removed. Ultimately this may translate to a suit that potentially behaves and feels more like a piece of athletic wear than a garbage bag."
The research was published in the journal Angewandte Chemie International Edition.
Source: NC State