Single-walled nanotubes are pure carbon cylinders with remarkable electronic properties. Pulickel Ajayan and his colleagues recently have discovered how to weld these nanotubes, paving the way for fabrication of molecular circuits and nanotube networks.

Ajayan and researchers in Germany, Mexico, the U.K., and Belgium used irradiation and heat to form the welded junctions. The research was featured in the Oct. 7 issue of Business Week’s “Developments To Watch.”

This is the first time single-walled nanotubes have been welded, although multi-walled nanotubes with junctions previously have been created using growth techniques. The electrical properties of single-walled nanotubes surpass those of multi-walled tubes. This is why so many researchers have been anxious to try this experiment, says Ajayan.

“No one knew if junctions could be created,” Ajayan says. “Single-walled carbon nanotubes are perfect cylinders without any defects. But, to create junctions between them, intertube carbon-carbon bonds need to form. The irradiation and heating process we use creates just enough defects for these bonds to form without damaging their electrical properties.”