ABERDEEN PROVING GROUND, Md. – The U.S. armed services have long wished chemical warfare agent protective material could be inherently incorporated in everyday clothing, scarves, and even tents. Existing protective materials rely on carbon filtration, which only traps rather than reacts with the bonds of chemical agents, so they quickly reach saturation and can leach chemical agent out later. Also, they require a separate suit put on over the uniform plus a full-sized mask, costing precious time during a chemical attack and reducing combat performance once on.
ECBC scientists are now teaming up with scientists at the Defense Threat Reduction Agency, the U.S. Army Natick Soldier Research, Development and Engineering Center, and North Carolina State University in a collaborative effort to create a uniform that destroys chemical agents on contact using a new kind of molecule called metal-organic frameworks, or MOFs for short.
MOFs are nano-constructed materials made of organic struts consisting of oxygen, hydrogen and carbon, and metals, commonly copper, zinc, or zirconium, acting as nodes. They form three-dimensional crystalline structures much like an erector set. The lattice-shaped structures have large void spaces, called pores.
The latest form of MOF ECBC scientists are working with, dubbed UiO-66-NH2, is especially promising. It is very stable in air, and in acids and solvents. It can also pull water from the atmosphere, which enhances its ability to destroy chemical agents. Finally, it can also be expanded in size by adding more struts and nodes, allowing for faster destruction of chemical agents.
Layering, Weaving or Growing
The challenge now is to find a way to embed these MOFs into fabric. Working with 12-inch square swatches of polymer fibers, the team has tried a technique of layering the MOFs into the fibers called atomic layer deposition. This method deposits a thin film of metal oxides onto the fibers, which is then used as a growth center for MOFs. Another method they are experimenting with is called electrospinning. It uses an electrical charge to turn a liquid polymer solution into many nanofibers that provide an ideal surface to deposit MOFs. Still a third method they are exploring is reactive dye chemistry, which is like conventional dying, but with the addition of creating crosslinking chains between the polymers. Those chains provide a surface for the MOFs to grow on.
The winner will be the technology that proves best at combining MOFs with the uniform fabric and is most readily scalable to go from 12-inch square swatches to 10-square-foot swatches that can be made into a full uniform.
“Right now we are at the point of understanding the optimal way to incorporate MOFs into fabrics,” said Greg Peterson, an ECBC research chemical engineer and leader of the ECBC team.
Less Burden is Better Protection
“One of the potential results of this research is replacing the current Joint Services Lightweight Integrated Suit Technology, called JSLIST, with an extra layer of protection in the combat uniform Soldiers already wear every day. The JSLIST is hard to put on, and when a gas mask is added, combat performance is reduced. We will replace it with a better uniform and a balaclava they can pull over the face plus gloves to achieve the same level of protection.” said Peterson
This lower burden chemical agent protection ensemble is at least a few years away according to Peterson. Once it is ready, however, Soldiers, Sailors, Marines and Airmen will all get the benefit of enhanced chemical agent protection that requires nothing more that pulling gloves and a balaclava out of their pants cargo pocket and slipping them on.
Editor’s Note: This article is part of a new series called “ECBC Science of Tomorrow.” Each quarter, the series will feature the latest cutting-edge scientific concepts being explored by researchers at the ECBC. The intent of “Science of Tomorrow” is to explore the variety of innovative ways ECBC could advance research, science and engineering to create new and effective chemical and biological defense solutions.