Effects of Varying the Content of Alcohol in the Reaction Mixture on the Graphitization of MWCNTs and Their Surface Functionalization

E. Segura-Cárdenas, D. Hernández-Arriaga, F.J. González-González, R. López-Sandoval, M. Reyes-Reyes
Universidad Autónoma de San Luis Potosí, MX

Keywords: nanotubes, surface functionalization, chemical reactivity, cristallinity

Summary:

We have studied the effect of the addition of different alcohol concentration (methanol, ethanol, octanol) in xylene on the quality and the functionalization of multi-walled carbon nanotubes (f-MWCNTs). The addition of very low alcohol concentration in the reaction mixture has negative effects in the average length of f-MWCNTs due to, possibly, the production of radicals different to –OH radicals during the sonication of the reaction mixture. As the alcohol concentration is increased, the formation of –OH radicals has a positive effect on the average length of f-MWCNTs. At a volume ratio around 1:0.1, xylene:alcohol, a relatively high alcohol concentration compared with other reports, the maximal increment in length of the nanotubes is obtained and the quality of the sample is improved. After this optimal concentration, the alcohol addition to the reaction mixture results in more –OH radicals and in stronger oxidative environment, which hinders the growth of f-MWCNTs. Moreover, the proportion between –OH radicals and carbon atoms of the alcohol molecule is responsible of the morphological and structural differences of the f-MWCNTs synthesized using the same concentration but different type of alcohol. Finally, the use of alcohol introduces functional groups on the walls of f-MWCNTs producing their functionalization.