Wetting, filling and decorating carbon nanotubes

The issues of wetting and filling carbon nanotubes are reviewed together with the possibilities of chemical modification of the nanotube surface. It is shown that all wetting and filling results are consistent with the existence of a surface tension cut-off value al c. 100-200 mN/m above which a liquid will no longer wet nanotubes. This limit is sufficiently high to allow wetting by organic solvents and liquid acids which can be used as low surface tension solvent carriers to introduce other materials (solutes) inside the nanotubes. The nanotube can also be decorated by first generating functional oxide groups on the surface through oxidation to enhance the reactivity of the otherwise relatively inert surface.