The World's Tiniest Tubes > Endeavors, Spring 2000

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Why People are Watching the World's Tiniest Tubes
by Neil Caudle

Otto Zhou can make them, and he’s learning how to use them. But so far, only Nature knows exactly how and why they form.

Carbon nanotubes, Zhou explains, materialize from a vapor after he uses a high-powered laser to blast a hole through a dime-sized pellet of graphite. The blasting is fiery and spectacular. The tubes are not. If you could actually see one, the tube would look something like a roll of chicken wire—a single layer of carbon atoms linked up in a fabric of hexagons.

But as modest as they seem, these little tubes have big possibilities, with attributes very much in demand for high-tech applications. They are as hard as diamond and tougher than graphite or steel. They can conduct (or semiconduct) electricity. But most important of all, they are tiny—much smaller than the carbon fibers used to reinforce some of today’s space-age materials.

Zhou and his students—including undergraduates—are putting the tubes through their paces, learning how to align them, imbed them in plastics, and assemble them into structures. So far, Zhou has been impressed with the nanotubes’ versatility and strength, though the tubes are costly and time-consuming to produce. (Zhou and others are investigating a different way of making the tubes, decomposing hydrocarbons to produce the tubes at lower temperatures and therefore lower energy costs.)

But even if nanotubes prove too costly for large-scale use in, say, tennis rackets, Zhou thinks they will probably find their way into smaller, high-value devices such as flat-panel computer screens, telecommunications gear, rechargeable batteries, and specialized lighting equipment.

Some of these products, Zhou says, are almost ready for market. Zhou and his collaborators have several industrial partners, including Lucent Technologies, which is testing a nanotube-based microwave signal amplifier for telecommunications. And Raychem Corporation, based in Research Triangle Park, is working with Zhou and Brian Stoner, lecturer in materials science, on devices to protect high-speed data lines from voltage surges. In tests, a nanotube-based gas-discharge tube—a relief valve for excess voltage—performed much more reliably than conventional tubes, which already comprise a $100 million market.

“That’s one advantage of working with industrial partners,” Zhou says. “They bring us problems that we didn’t even know existed. Before this work, I’d never even heard of a gas-discharge tube.”

The U.S. Navy has come to call with some technical questions of its own, providing more than $5 million in research funding over five years. Zhou and Sean Washburn direct the North Carolina Center for Nanoscale Materials, funded by the Office of Naval Research. Involving 15 faculty members from UNC-Chapel Hill, Duke, and N.C. State University, the center explores the fundamental science of nanoscale materials and their use in commercial applications. North Carolina’s team landed the grant despite stiff competition from the likes of Harvard, Berkeley, Rice, and other heavyweights in materials science.

“We are in a very good position nationally because we can put together the whole package—with several UNC departments, our industrial partners, and collaborators from the Research Triangle,” Zhou says. “Also, this is an environment where people actually work together rather than having their own small kingdoms.”

The Office of Technology Development (OTD) is the only UNC-CH office authorized to execute license agreements with companies. For information on reporting inventions, contact OTD at 919/966-3929.

Houston, We Have Some Cool Problems

When Rachel Rosen came to Carolina as a freshman from Houston, Texas, it never occurred to her that she would, by her senior year, be using a $140,000 instrument to do research into advanced problems in materials science. Rosen, a physics major, works in Otto Zhou’s lab inserting carbon nanotubes into plastics, looking at how nanotubes affect the thermal properties of the material.

“I like working with these new materials,” she says. “When I get an idea, I can try it and see the results almost immediately. And in this field, there’s a good combination of pure science and application.”

Rosen, who wants to go to graduate school and become a scientist, has won an undergraduate research award from the Materials Research Society and has published two papers in Applied Physics Letters. She says that part of the appeal of her work in Zhou’s lab has been the chance to work with students from all over the world.

“Yes, we do come from lots of different cultures. But the thing is, I don’t really notice a cultural difference, just a difference in interests and expertise. What matters is, we’re working toward a common goal.”

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