Fiber spun from nanotube smoke

Researchers from the University of Cambridge in England have developed a relatively simple way to manufacture continuous fibers of carbon nanotubes.

Carbon nanotubes are rolled-up sheets of carbon atoms that are stronger than steel by weight, have useful electrical and optical properties, and can be narrower than a single nanometer. A nanometer is one millionth of a millimeter.

The relatively simple method promises to make it possible to more cheaply produce carbon nanotubes in bulk. It could also eventually produce fiber that rivals carbon fiber in strength, but that is more flexible. Carbon nanotube fibers are able to twist, opening the way to flexible materials, multistrand threads and threads made from a mix of materials.

The researchers spun continuous, twisted fibers directly from the furnace where carbon nanotubes were produced. The researchers injected a liquid mix of ethanol, ferrocene and thiophene into a flow of hydrogen gas in a furnace heated to between 1,050 and 1,200 degrees Celsius to produce nanotube aerogel, or elastic smoke. The keys were closely controlling conditions and drawing the nanotube aerogel continuously using a rotating spindle. Existing nanotube fiber methods use previously formed nanotubes.

In theory, the method can produce nanotube fiber of any length, according to the researchers. They have also developed a related technique for coating objects with layers of carbon nanotubes.

The method could be used to synthesize carbon nanotubes in bulk within two years and to make practical fibers in 5 to 10 years, according to the researchers. The work appeared in the March 11, 2004 issue of Science.