US Patent 7939047 - Bandgap separation of CNTs

http://www.freepatentsonline.com/7939047.html

This patent from Rice University teaches a chromotographic separation of functionalized carbon nanotubes based on the semiconductor bandgap. Claim 1 reads:

1. A method for separating CNTs by type, the method comprising the steps of:

a) dispersing a plurality of CNTs of different type as individual nanotubes in a solvent to form a first mixture;

b) selectively-functionalizing metallic and semi-metallic CNTs within the first mixture using a first diazonium species, in sub-stoichiometric amount, to yield a second mixture comprising selectively-functionalized metallic and semi-metallic CNTs and unfunctionalized semiconducting CNTs;

c) reacting the CNTs in the second mixture with a second diazonium species to yield a third mixture comprising differentially-functionalized metallic and semi-metallic CNTs possessing a first chemical property and functionalized semiconducting CNTs possessing a second chemical property; and

d) performing at least one chromatographic separation on the third mixture, so as to separate the differentially-functionalized metallic and semi-metallic CNTs from the functionalized semiconducting CNTs on the basis of their functionalization-induced differential chemical properties.