Chemists Decorate Nanotubes for Usefulness
Gorman, J., Science News
In a step that could lead to harder materials and tinier electronic devices, researchers have found a promising new way to attach molecules to carbon nanotubes.
In its simplest form, a carbon nanotube is a one-atom-thick sheet of carbon curved into a cylinder. Such tubes exhibit extraordinary strength and electrical conductivity. For many potential uses of carbon nanotubes, chemists need to attach clusters of atoms, called functional groups, to the outsides of the tubes. The new report, which will appear in an upcoming issue of the JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, demonstrates a novel way to do just that.
Researchers have had some success with adding functional groups to carbon nanotubes. But the new method is simpler and can attach a greater variety and number of groups, says research team member James M. Tour of Rice University in Houston. The process can attach a functional group to as many as 1 out of every 20 carbons on a nanotube, which can contain millions of carbon atoms.
Tour and his colleagues used a technique similar to one by which chemists link functional groups to graphite, which forms from flat sheets of carbon. The Rice researchers attached an electrode to apply a voltage to a mesh of carbon nanotubes known as bucky paper. Then, to link each type of chemical group to the nanotubes, they bathed the bucky paper in a solution containing a different aryl diazonium salt.
Each molecule of an aryl diazonium salt contains a six-carbon ring, to which the researchers had attached one of a variety of functional groups. Joined to one of the ring's five other carbon atoms was a different chemical group that the scientists expected would readily get knocked off as the molecule approached the charged bucky paper. …