ABSTRACT
Nonfunctionalized CNTs are dif£cult to dissolve or disperse in most organic or inorganic solvents because of their long-structured features, large molecular size, or severe aggregation. The common agents used to help disperse CNTs are surfactants, which, however, can only increase the dispersibility to a limited extent, and surfactants do not affect the solubility of CNTs. Current chemical methods for water suspended SWNTs require harsh sonochemical treatments to effectively disperse nanotubes. However, these methods are currently incapable of conferring thermodynamically stable water-based dissolutions of carbon structures since surfacted SWNT solutions are simply metastable colloidal suspensions, where they transiently individualize but always reaggregate over time since this is their thermodynamically favorable state. Therefore, true water-soluble nanotube solutions are those solutions that entropically favor individualized nanotubes,2 where the reaggregation of CNTs in a solvent is less favored, on a thermodynamic basis, than their continued solvated state.3 In some embodiments, the extent of functionalization is dependent upon a number of factors, for example, the reactivity of the CNTs, the reactivity of the functionalizing agent, steric factors, etc. In some such embodiments, as a result of such dependencies, the extent of functionalization can be in the range of from at least about 1 functional group per every 1000 CNT carbons to at most about 1 functional group per every 2 CNT carbons.
