Liquid-Phase Exfoliation of Nanotubes and Graphene

Many applications of carbon nanotubes require the exfoliation of the nanotubes to give individual tubes in the liquid phase. This requires the dispersion, exfoliation, and stabilization of nanotubes in a variety of liquids. In this paper recent work in this area is reviewed, focusing on results from the author's group. It begins by reviewing stabilization mechanisms before exploring research into the exfoliation of nanotubes in solvents, by using surfactants or biomolecules and by covalent attachment of molecules. The concentration of dependence of the degree of exfoliation in each case will be highlighted. In addition research into the dispersion mechasim for each dispersant type is discussed. Most importantly, dispersion quality metrics for all dispersants are compared. From this analysis, it is concluded that functionalized nanotubes can be exfoliated to the greates degree. Finally, the extension of this work to the liquid phase exfoliation of graphite to give graphene is reviewed.