Joined: 16 Mar 2004
|Posted: Mon Dec 18, 2006 10:33 am Post subject: Scientists use soap to sort nanotubes
|Scientists use soap to sort nanotubes
U.S. scientists say they've found a soap-based approach can be used to solve a long running problem in the sorting of types of carbon nanotubes.
Carbon nanotubes and their excellent electronic and mechanical properties have been at the center of nanotechnology research with just one major problem: making nanotubes always produces a mixture of metallic and semiconducting nanotubes. Various methods for separating the two types of have been demonstrated but all have complications.
But Mark Hersam and colleagues at Northwestern University have found a solution - a soap solution. The researchers say the procedure involves wrapping the nanotubes with a mixture of surfactants - or soaps - and then spinning them in a high-speed centrifuge for up to 24 hours.
The centrifuge spins at 64,000 revolutions per minute, generating forces that are some 170,000 times stronger than the force of gravity. That allows the metallic and semiconducting nanotubes, which have different densities, to be separated and, the researchers add, it's also possible to sort the nanotubes according to diameter.
The project is explained in the current, inaugural issue of the journal Nature Nanotechnology.
This story was first posted on 9th October 2006.