Dispersion Free Energy of Carbon Nanotubes in Water Systems

Dispersion free energies of pristine, carboxyl-functionalized (oxidized), and methyl-functionalized carbon nanotubes (CNTs) are calculated by combining molecular dynamics simulation with the thermodynamic integration method. The results show that the steric effect of the functionalized group on the CNT surface contributes to the dispersion of CNT, regardless of whether the chemical group is hydrophilic or hydrophobic. Moreover, modulating the steric effect degree can be helpful in dispersing CNT bundles not only in water but in any solvent.