Functionalization of carbon nanotubes via dissolving metal reductions

In this study we present direct sidewall functionalization of single-walled nanotubes, carried out via two different dissolving metal reduction methods. A modified Birch reduction scheme and a novel synthetic route were applied to form carbanion complexes on the surface of the nanotubes in liquid NH3 and tetrahydrofuran, respectively. The carbanion complex was reacted with a series of alkyl and aryl halogenides resulting in the corresponding SWNT derivatives. We determined the chemical composition and the thermal stability of the functionalized nanotubes by thermogravimetry/mass spectrometry and pyrolysis-gas chromatography. Characteristic decomposition peaks, observed in the temperature range of 350-600 degrees C, suggest the formation of covalent derivatives upon functionalization that is also supported by Raman spectroscopic studies. The influence of the functional groups and the type of nanotubes on the thermal stability, as well as the relationship between the functional group content and the intensity of the Raman D peak are discussed.