Exploring the mechanisms of carbon-nanotube dispersion aggregation in a highly polar solventD. Mac Kernan1 and W. J. Blau2
1 School of Physics, University College Dublin - Dublin 4, Ireland, EU
2 Molecular Electronics and Nanotechnology, Trinity College Dublin - Dublin 2, Ireland, EU
received 23 April 2008; accepted in final form 29 July 2008; published September 2008
published online 12 September 2008
One of the main obstacles to the exploitation of single-wall carbon nanotubes (SWCNT) remarkable electronic and materials properties is their tendency to form ropes or bundles. This complicates drastically the processing and purification of carbon nanotubes. An understanding of the free energy landscape associated with transitions from isolated SWCNTs to bundles in solution would facilitate the control of the process, and is the motivation of this work. Extensive molecular dynamics studies of this problem for the highly polar solvent, N-methyl-2-pyrrolidone (NMP) indicate that i) pairs of SWCNTs in the form of bundles are far more stable than pairs of isolated tubes; and ii) free energy barriers lying between bundles and isolated tubes exist which are proportional to the surface tension of NMP, and are likely to be responsible for the long-lived transients reported in experiments.
61.46.Fg - Nanotubes.
61.48.De - Structure of carbon nanotubes, boron nanotubes, and closely related graphitelike systems.
07.05.Tp - Computer modeling and simulation.
© EPLA 2008