Breathable Carbon Nanotube Membrane For 'Smart Uniforms'
Lawrence Livermore National Laboratory scientists are working on a breathable, protective material made from aligned carbon nanotube (CNT) channels. It should be a perfect fabric for "smart uniforms" that will protect military personnel in different hazardous environments.
This material is the first key component of futuristic smart uniforms that also will respond to and protect from environmental chemical hazards. The research appears in the July 27 edition of the journal, Advanced Materials (link is external).
High breathability is a critical requirement for protective clothing to prevent heat-stress and exhaustion when military personnel are engaged in missions in contaminated environments. Current protective military uniforms are based on heavyweight full-barrier protection or permeable adsorptive protective garments that cannot meet the critical demand of simultaneous high comfort and protection, and provide a passive rather than active response to an environmental threat.
The LLNL team fabricated flexible polymeric membranes with aligned carbon nanotube (CNT) channels as moisture conductive pores. The size of these pores (less than 5 nanometers, nm) is 5,000 times smaller than the width of a human hair.
"We demonstrated that these membranes provide rates of water vapor transport that surpass those of commercial breathable fabrics like GoreTex, even though the CNT pores are only a few nanometers wide," said Ngoc Bui, the lead author of the paper.
To provide high breathability, the new composite material takes advantage of the unique transport properties of carbon nanotube pores. By quantifying the membrane permeability to water vapor, the team found for the first time that, when a concentration gradient is used as a driving force, CNT nanochannels can sustain gas-transport rates exceeding that of a well-known diffusion theory by more than one order of magnitude...
"The material will be like a smart second skin that responds to the environment," said Kuang Jen Wu, leader of LLNL's Biosecurity & Biosciences Group. "In this way, the fabric will be able to block chemical agents such as sulfur mustard (blister agent), GD and VX nerve agents, toxins such as staphylococcal enterotoxin and biological spores such as anthrax."
Fans of the terrific 1999 novel Starfish by Peter Watts will recall the permeable "diveskin""
She twists out of reach without a word, bending down to seal the [dive]skin on her leg. Fischer watches the leggings slide up her body. They seem almost alive. They are almost alive, he remembers. The 'skin's got these reflexes, changes its permeability and thermal conductivity in response to body temperature. Maintains, what's the word, homeostasis.
(Read more about the diveskin.)