Patent ID: 7884300

Claim:
A method of separating carbon nanotubes by dispersing metallic carbon nanotubes included in carbon nanotubes and then separating said metallic carbon nanotubes from semiconducting carbon nanotubes that did not disperse, characterized by comprising: adding to an amine solution the carbon nanotubes from which metallic carbon nanotubes are to be dispersed, without pretreating the carbon nanotubes by oxidization nor by heating; selectively unbundling the metallic carbon nanotubes in the amine solution relative to the semiconducting carbon nanotubes, said selective unbundling consisting of sonication of the amine solution conducted to unbundle the metallic carbon nanotubes as individual nanotubes, wherein as a result of subjecting to sonication the amine solution including the carbon nanotubes without the pretreatment, bundled carbon nanotubes in the amine solution are unbundled in conditions wherein metallic carbon nanotubes, to which the amine is physically more adsorbed than to semiconducting carbon nanotubes, do not return to a bundled state but remain dispersed in the dispersion while semiconducting nanotubes having weaker interaction with the amine than do metallic carbon nanotubes remain entangled with one another; and separating entangled carbon nanotubes as semiconducting carbon nanotubes from said amine solution by centrifugation.