Cluster origin of the transfer phenomena of single-wall carbon nanotubes

It is discussed the existence of single-wall carbon nanotubes (SWNTs) in organic solvents in the form of clusters. A theory is developed based on a bundlet model, which enables describing the cluster-size distribution function. Comparison of calculated solubilities with experiments would permit obtaining energetic parameters characterizing the interaction of an SWNT with its surrounding. Fullerenes and SWNTs are objects whose behaviour in many physical situations is characterized by peculiarities, which show up in that these systems represent the only soluble forms of carbon, what is related to their molecular structures. The fullerene molecule is a virtually uniform closed spherical-spheroidal surface, and an SWNT is a smooth cylindrical unit. Both structures give rise to weak interactions between the neighbouring units in a crystal and promote their interaction with solvent molecules. Another peculiarity is related to their trend to form clusters consisting of a number of fullerene molecules or SWNTs. The interaction energy of a fullerene molecule or SWNT with solvent molecules is proportional to the surface of the former and roughly independent of the orientation of the latter. The phenomena have a unified explanation in the bundlet model, in which the free energy of an SWNT in a cluster is combined from two components, viz a volume one proportional to the number of molecules n in a cluster, and a surface one, proportional to n(1/2). The membranous character of growth process in clusters allows explaining the dispersion of data. Growth mechanisms of fractal clusters in fullerene solutions are analyzed along with similarity laws determining the thermodynamic characteristics of fullerite crystals.