The new fabric material contains nanoscale fibers. These fibers have a special property: they can degrade most chemical warfare agents. The fibers are capable of breaking down toxic chemicals into harmless subparts.
To fashion the fabric, the chemists took uniform coatings of metal-organic frameworks and synthesized these on top of the nanofibers. This led to what the researchers describe as special kebab-like structures. Nanofibers are defined as fibers with diameters less than 100 nanometres; they can be produced by processes like melt processing, interfacial polymerization, electrospinning, antisolvent-induced polymer precipitation and electrostatic spinning.
The new fabric has a key advantage over other fabrics designed to minimize the risks from chemical weapons. Current materials tend to be made from carbon. Carbon is very effective at absorbing chemicals; however, the element is incapable of degrading the chemicals it absorbs, meaning that risks remain ever present.
This is why, as lead researcher Junjie Zhao of North Carolina State University explains to Controlled Environments magazine “our goal was to develop new materials that can detoxify these chemical warfare agents compounds, and we’ve been successful.”
To achieve this, special metal-organic frameworks were required. Most metal-organic frameworks come in the form of a powder. Due to issues of instability, the researchers tried a new trick – they wanted to see if they could grow special metal-organic frameworks as functional coatings onto fibers.
With this, the chemists deposited a thin film of titanium oxide (a naturally occurring oxide of titanium) onto a fabric made of nanoscale fibers. This was undertaken using a vapor-phase technology called atomic layer deposition. Atomic layer deposition is a thin film deposition technique that is based on the sequential use of a gas phase chemical process. It is a very controlled method and it produces a film to an atomically specified thickness.
The process allowed the chemists to apply various zirconium-based metal-organic frameworks onto the nanofibers in an evenly distributed way (the ‘kebab-like’ structure.)
This process was successful and the approach proved especially useful in creating coatings for masks, filters and protective garments. The fabrics were tested against a range of chemical agents, including the nerve agent soman. The nerve agent was neutralized in around 2 minutes.
Soman (chemically – O-Pinacolyl methylphosphonofluoridate) is an extremely toxic chemical substance. It is a nerve agent, interfering with normal functioning of the mammalian nervous system by inhibiting the enzyme cholinesterase. In addition to the direct toxic effects on the nervous system, people exposed to soman can experience long-term effects, many of which are psychological.
As well as military uses the thin coasting films could be used for personal security as well as other civilian and commercial uses.
The research has been published in the journal Angewandte Chemie International Edition, in a paper titled “Ultra-Fast Degradation of Chemical Warfare Agents Using MOF-Nanofiber Kebabs.”
This article is part of Digital Journal’s regular Essential Science columns. Each week we explore a topical and important scientific issue. Last week we considered new research which shows the hidden life in the depths of the oceans. The week before we looked at a why some mosquitoes elect to bite people and other prefer other animals.
