Carbon nanotubes are lightweight, stronger than steel and conduct electricity as well as copper. But making long wires from them, which would be useful in the real world, has proved extremely difficult. Until now. For the first time, scientists at Rice University have made threadlike carbon nanotubes that can be spun onto spools like wires, using industrial-scale methods.
"We finally have a nanotube fiber with properties that don't exist in any other material," lead researcher Matteo Pasquali said in a press release. "It looks like black cotton thread but behaves like both metal wires and strong carbon fibers." Pasquali is a professor of chemical and biomolecular engineering and chemistry at Rice University.
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The ability to manufacture and commercialize high-strength carbon nanotube fibers could revolutionize everything from satellites to electric vehicles to electronic devices and could lead to innovations in electronic textiles and even space elevators that carry cargo from Earth to the Moon.
A carbon nanotube is basically a bunch of carbon atoms arranged in a pattern that looks like chicken wire and then rolled into a tube shape. Since they were developed back in the 1990s, carbon nanotubes have been regularly experimented upon by scientists trying to get millions and billions of these tubular structures to all point in the same direction. When the nanotubes are aligned, their atoms attract each other and provide superior strength overall.
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But previous methods of arranging nanotubes usually resulted in the structures pointing in different directions and clumping together. Fibers made from misaligned nanotubes weren't very strong, nor were they as electrically conductive as the individual tubes.
Pasquali and his team decided to try a "wet spinning" method. They dissolved the nanotubes in chlorosulfonic acid, used in detergents and synthesizing saccharine. Then they extruded the mix through small openings. The process is similar to that used to make Kevlar; it produced fibers about 25 to 50 microns across made of millions of nanotubes, all lined up and bound together.
The process is scalable, which means that it's possible to make the nanotube fibers at industrial scales. And there are lots of uses for a flexible thread that has all the good qualities of metal wire and none of the bad, such as brittleness, corrosion or overheating.
The work was reported in the Jan. 11 issue of the journal Science.
Credit: Rice University