Asymmetric end-functionatization of carbon nanotubes

The asymmetric end-functionalization of carbon nanotubes, was investigated. A method was developed in which free-standing films of vertically aligned multi-walled carbon nanotubes (MWCNTs) floating at the air-liquid interface, were modified by a chemical reagent added to the liquid phase. To obtain the arrangement, nanotube arrays grown via chemical vapor deposition (CVD) on quartz glass substrates, were floated on an aqueous hydrofluoric acid solution. The films were prevented from dwindling by combining the hydrophobic CNTs with either a hydrophilic solvent or a lower polarity solvent of high density. Chemical modifications were made by transferring the films onto a solution having a solvent. The final array of MWCNTs was obtained by placing the films with reverse orientation onto a second modifier solution and performing a second UV irradiation. The functionalization was confirmed using X-ray photoelectron spectroscopy (XPS).