Dispersing carbon nanotubes by star-like water soluble C60 derivatives

The properties of three water soluble [3:3] hexakisadducts of C60 1-3 are investigated both in bulk aqueous solutions and at air/water interface. 1-3 have a star-like molecular structure with six hydrophilic quarternary ammonium groups located terminally. 2 and 3 also have increasing number of ethylene oxide groups inserted into their peripheral hydrophilic arms. This molecular structure makes 1-3 highly water soluble, thus difficult to form aggregates in bulk aqueous solutions as revealed by transmission electron microscope observations. But surface tension measurements shows 1-3 still own some amphiphilic properties and can lower the surface tension of water. These unique C60 derivatives are also subjected to disperse carbon nanotubes (CNTs) in water for the first time. It was found the ability of each water soluble C60 derivative to disperse CNTs was mainly dominated by their amphiphilic feature as well as molecular weight.