When single-walled carbon nanotubes (SWNTs) are
functionalized, they are mostly bundled. To exploit their
properties, they must be unbundled into individual nanotubes,
but this is difficult because of the high intermolecular
cohesive forces. A few processes yield individual tubes and
small bundles, but only in small amounts over long reaction
times using harsh solvents or costly equipment.
Researchers at Rice University led by James M. Tour have
devised a rapid and environmentally benign ‘green’ process
using ionic liquids (ILs) to exfoliate the bundles and diazonium
chemistry to derivatize predominantly individual SWNTs [Price
et al., J. Am. Chem. Soc. (2005) 127 (42), 14867].
ILs are salts that are nonvolatile liquids at room temperature
(with boiling points >200°C), and hence can be recycled. The
reaction occurs in minutes at room temperature by just
grinding the SWNTs in a mortar and pestle with an
imidazolium-based IL and a K2CO3 base. The IL’s counterion
exfoliates the negatively charged bundles by intercalating
between them. This allows the diazonium species to react
When single-walled carbon nanotubes (SWNTs) arefunctionalized, they are mostly bundled. To exploit theirproperties, they must be unbundled into individual nanotubes,but this is difficult because of the high intermolecularcohesive forces. A few processes yield individual tubes andsmall bundles, but only in small amounts over long reactiontimes using harsh solvents or costly equipment.Researchers at Rice University led by James M. Tour havedevised a rapid and environmentally benign ‘green’ processusing ionic liquids (ILs) to exfoliate the bundles and diazoniumchemistry to derivatize predominantly individual SWNTs [Priceet al., J. Am. Chem. Soc. (2005) 127 (42), 14867].ILs are salts that are nonvolatile liquids at room temperature(with boiling points >200°C), and hence can be recycled. Thereaction occurs in minutes at room temperature by justgrinding the SWNTs in a mortar and pestle with animidazolium-based IL and a K2CO3 base. The IL’s counterionexfoliates the negatively charged bundles by intercalatingbetween them. This allows the diazonium species to react
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