Military Mixes "Smart" Coatings

Continued from page 1

By David Essex

February 21, 2003

To sense its environment, receive commands, and propagate color changes from one molecule to the next, the coatings will need wiring. At Clemson, researchers think carbon nanotubes may serve; they fill the tubes with iron to create rudimentary circuits, although it's still unclear whether this low-power approach can create the range of colors the Army needs. Back at the New Jersey Institute of Technology, their collaborators are working to control the nanotubes with electricity, light, and laser, says Joseph Argento, deputy of the Army's Industrial Ecology Center at Picatinny.

The collaboration is investigating micro-electromechanical systems (MEMS), under study elsewhere at Picatinny, though there's doubt the microscopic machines will provide the right mix for smart coatings. "That's still a sexy technology," says Laura Battista, an environmental engineer at Picatinny who works on smart coatings. "But there's nothing off the shelf right now." MEMS could be useful, however, in "screens" that make vehicles invisible to satellites, say these researchers.

The ultimate goal, Watts says, is to display an image of the vehicle's surroundings on its surface. But here's one problem: getting the false image to blend in convincingly might require mounting the camera near the observer-the enemy, in this case. Watts says the Army might settle for a second-best "chameleon" effect that rapidly changes from one pattern to another.

Flip a Switch, Paint Your House

Smart coatings will find applications beyond the military, researchers say. Watts envisions corrosion-resistant cars that can be customized on the spot, programmable billboards, and color-changing fabrics. The exteriors of buildings could be redesigned with the flick of a switch. Car companies are in the process of developing self-healing bumpers, Argento says. "You can just imagine what this coating could do for buildings and bridges that you don't have to worry about corroding," he adds.

Despite the formidable hurdles, the researchers aim to produce a prototype as early as 2005 (although possibly as late as 2009) if the money lasts. Components-such as self-healing adhesives that aren't exposed to the elements-could arrive sooner. "We're building a good, solid technical basis that suggests this should be possible," says Watts. "What is still unknown is how it all will be integrated."