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Sci-Tech

Future nanotech tools made from clay

A nano start-up is using a naturally occurring tubular clay as a carrier in metals, perfumes and more.

BURLINGAME, Calif.--The next big nanotech product, according to start-up NaturalNano, will be dug out of the ground.

The Rochester, N.Y.-based company has found a way to use Halloysite, a naturally occurring tubular clay, as an unobtrusive carrier in metals, perfumes and other substances.

NaturalNano says that by filling Halloysite tubes with copper and then mixing the tubes into a polymer, a manufacturer could make an electrically conductive plastic. If filled with fungicides, the Halloysite particles--which consist of aluminum, oxygen, silicon and hydrogen--could be swirled into paint to make it more resistant to mildew and mold. Time-released coatings could also be added to make all-day deodorant.

Dragon Mine deposits
Credit: NaturalNano
Dragon Mine deposits in Utah are
significantly rich in nanotube content.

The tubes could even have agricultural uses.

"If you load the tube with a common pesticide, an insect can pick it up by brushing up against it," Aaron Wagner, director of research and development for NaturalNano, said during an interview at the Foresight Nanotechnology Conference in Burlingame. "There are some nasty chemicals used in agriculture today and we'd like to reduce the amount of the nasties."

Spreading pesticides in this manner could cut down the amount of poison sprayed on a field by 70 or 80 percent, he speculated.

Futurists often speak about how nanotechnology will alter semiconductors and other technologies, but the first generation of nanotechnology applications revolve around some pretty prosaic stuff: lighter car door panels for better gas mileage, stain-free pants, better plastics. Nanotechnology involves building products or enhancing existing products with designer molecules that measure 100 nanometers or less. (A nanometer is a billionth of a meter.) The applications also help explain why nanotech entrepreneurs haven't become overnight billionaires: Textile and plastics manufacturers can't raise their prices easily.

Halloysite through microscope
Credit: NaturalNano
Researchers use transmission electron
microscopes to view the Halloysite
nanotubes from Atlas mines in Utah.

Halloysite itself isn't exactly new. For centuries, artisans have used Halloysite clay to make porcelain and china. Armed with high-powered microscopes in the 1950's, scientists saw that Halloysite particles were tube shaped. Applications to take advantage of the particles' structure finally emerged in the '90s.

No one really fully understands why Halloysite forms into tubes, he said. One theory is that it's a result of shearing; other researchers believe interaction with water causes Halloysite sheets to roll into tubes.

The fact that the tubes can be dug from the ground, however, means that they are somewhat cheap, and far less expensive than similar, manmade objects like carbon nanotubes.

Some carbon nanotubes cost $250 a gram and are made in furnaces in labs. By contrast, Halloysite comes out of mines. NaturalNano gets its raw material from the Atlas Dragon Mine in Utah.

"We buy by the ton," Wagner said. "I don't think you can beat us on price. Nature spent billions of years on R&D."

Halloysite tubes are generally about 40 to 200 nanometers in diameter and about a micron long. A micron is a millionth of a meter, so the tubes resemble hollow spaghetti.

NaturalNano has patents pending for its method of extracting the tubes from raw clay (which can contain other materials) and then processing them for industrial applications.

Wagner would not state when products containing the company's tubes would debut or who NaturalNano's customers are. Nonetheless, he said the tubes would be likely to first appear in plastics and particles. Fungicides and agricultural applications would be likely to follow later. And in the more distant future, the tubes might be used for human drug delivery.

NaturalNano expects that prices for finished Halloysite nanotubes will run from $3.50 per pound to $20 per pound, depending on function and complexity. The company says it is laying the groundwork for an IPO.

"Our goal is to be a public company by the end of the year," Wagner said.