Theoretical investigations on C60 -ionic liquid interactions and their impacts on C60 dispersion behavior

Increased use and production of carbon nanomaterials (e.g., fullerene C60 ) and ionic liquids (ILs) may result in their concomitant releases into the environment. Inevitably there will be interactions between carbon nanoparticles (CNPs) and ILs. However, experimental data on the interaction of CNPs with ILs are not readily available, and the mechanism behind the interactions is still elusive. To contribute to an understanding of the molecular interactions established between CNPs and ILs, theoretical investigations at multiple levels were performed to determine the interactions of C60 with 6 different imidazolium-based ILs. The results indicate that C60 mainly interacts with the IL molecules through the van der Waals, π-cation, and hydrophobic interactions. Mulliken population analysis suggests that charge transfer occurs from the IL to C60 during the C60 -IL interaction. The self-diffusion coefficient (D) of C60 in [C60  + IL] systems reaches the maximum in the case of moderate C60 -IL interaction (interaction energy, EINT ), implying that in this case a good dispersion of an agglomerate species of C60 is obtained. The D value of C60 in [C60  + IL +water] systems increases with an increase of the EINT , implying that the presence of ILs can play an important role in the aqueous dispersion of the C60 agglomerate.