Improving the Degree of Functionalization and Solubility of Single-Walled Carbon Nanotubes via Covalent Multiple Functionalization

The synthesis of covalent multi-functionalized single-walled carbon nanotubes (SWNT) via the combination of two diazonium salt addition reactions with tetrabutylammonium hydroxide to form carbon nanotube salts was carried out. The formation of carbon nanotube salts allows SWNT to be easily dissolved in common solvents, which increases the processing capability of the SWNT. The dissolutions of some of the obtained products can be increased three-fold through multi-functionalization. Thus tetrabutylammonium cation plays an extraordinarily important role; i.e., balancing the charges on the functionalized SWNT surface and de-bundling of the functionalized SWNT. This approach provides a useful way of preparing some SWNT-containing biomaterials. The multi-functionalized SWNT were confirmed by standard techniques used for carbon nanotube characterization.