Chemistry

Salting in Nanotubes

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Science  24 Dec 2004:
Vol. 306, Issue 5705, pp. 2165
DOI: 10.1126/science.306.5705.2165a

Single-walled carbon nanotubes (SWNTs) are of interest because of their outstanding mechanical and electrical properties, and the tendency of SWNTs to aggregate into bundles has been overcome by modifying them chemically, dissolving them in superacids, or by sonicating them with the addition of surfactants or polymers. Unfortunately, all of these methods are based on an intercalating mediator that prevents the strong sidewall van der Waals forces from reaggregating the tubes, and many of these methods cut or damage the tubes.

Pénicaud et al. show that SWNTs can be reduced using alkali metals to form polyelectrolyte salts that dissolve in aprotic polar organic solvents such as dimethyl sulfoxide. Elemental analysis indicated that the metals removed one negative charge for every 10 carbon atoms; however, only one of five charges was dissociated, whereas the others were balanced by the condensation of alkali cations. The nanotube polyelectrolyte solutions appear to be stable indefinitely, although they need to be kept under an inert atmosphere because the reduced SWNTs are sensitive to air. — MSL

J. Am. Chem. Soc. 10.1021/ja0443373 (2004).

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