AB-INITIO STUDY OF THE INTERACTION OF SINGLE WALLED CARBON NANOTUBES WITH SOLVENT MOLECULES

Chu Chun Fu and Pablo Ordejon
Service de Recherches de Métallurgie Physique CEA/Saclay, FR

Keywords: ab-initio calculation,, carbon nanotubes, good solvent

Abstract:
AB-INITIO STUDY OF THE INTERACTION OF SINGLE WALLED CARBON NANOTUBES WITH SOLVENT MOLECULES Chu Chun Fu Service de Recherches de Métallurgie Physique, CEA/Saclay, 91191 Gif-sur-Yvette, France Pablo Ordejon Institut de Ciencia de Materials de Barcelona - CSIC, Spain Single walled carbon nanotubes (SWCNT) have been intensively studies from both experimental and theoretical point of view due to their potential application in nanoelectronic devices, among many others. However these nanotubes are usually grown as bundles containing 10-1000 individual tubes, joined by Van der Waals forces. The separation of these bundles into free-standing tubes is a pre-requisite for many applications. Some solvents such as N,N-dimethyl-formamide (DMF) and N-methyl- pyrrolidinone (NMP) have been found to be excellent to make solutions having individual suspended nanotubes, without the need of using any surfactant as it is the case when water is used [1]. Although a Lewis basicity without hydrogen donors has been suggested experimentally to be an important condition for a good solvent, this may be a necessary but not sufficient condition since DMSO (dimethyl sulfoxide), a bad solvent, is an exception [2]. So the key condition of a good solvent for carbon nanotubes is still unknown. In this work we perform theoretical studies of adsorption of some solvent molecules in both semiconducting and metallic SWCNT's, trying to understand which are the essential properties differentiating 'good' solvent (DMF and NMP) from 'bad' ones (Water, DMSO, etc.), as well as to compare the interaction properties of these solvent molecules with semiconducting and metallic tubes in order to see if there is any selected solubilization of nanotube bundles. Different equilibrium positions, adsorption energies, charge transfer and electronic band structures are investigated by means of first principles Density Functional Theory calculations using numerical atomic orbitals as basis sets. References: [1] Liu et al. Chem. Phys. Lett. 303, 125 (1999) [2] Ausman et al. J. Phys. Chem. B 104, 8911 (2000)

NSTI Nanotech 2003 Conference Technical Program Abstract