Hazmat suits to protect against biological and chemical attacks are often made of thick, synthetic rubber that's impervious to the nastiest substances. But they're also impervious to sweat, and people wearing them can typically only work for short periods before succumbing to exhaustion, heat stroke and, occasionally, death.
Now, a joint team of scientists from the University of Colorado and private firm TDA Research have developed a breathable rubber suit made from butyl rubber impregnated with liquid-crystal molecules.
Cross-linked with the rubber, the liquid-crystal molecules arrange themselves into tiny tubes big enough to allow the passage of water molecules but too small for toxic chemicals.
"(The liquid-crystal molecules) organize around water to make little nanoscale water conduits," said the suit's co-inventor, Douglas Gin, a professor of chemistry at the University of Colorado. "These little tunnels never dry out and they let water vapor, or anything that's water-soluble, go in and out."
Gin said most biochemical agents are made of molecules significantly larger than the 1.2-nanometer-wide tubes, and thus are unable to enter through the rubber. Further, a chemical agent that small would likely be hydrophobic (repelled by water), and would not be able to pass through the material's pores.
"If you can (achieve permeability) with butyl and still have it reject the chemicals that you don't want, you've built a better mousetrap," said Bob Weiss, a professor of chemical, materials and biomolecular engineering at the University of Connecticut who wasn't involved in the research. "It's going to be very exciting."
This new breathable rubber is very similar to Gore-Tex, a material commonly used in waterproof clothing, said co-inventor Brian Elliot of TDA Research.
"The pores in Gore-Tex are 100 times larger than the pores in our membranes," he said.
The scientists say they have created a few hundred samples of the breathable rubber, and are looking for ways to get the suit approved for military purposes, a process that can take up to five years.
Another possible application of the breathable rubber is to purify salt water, Gin said.
"We've done lab single-salt mixtures and have been able to get the salt out as good as commercial desalination," Gin said.
Gin and Elliot's work is published in the latest issue of the journal Advanced Materials.
