Transport behavior of water confined in carbon nanotubes

The transport properties of water confined in single-walled carbon nanotubes with diameters from 1.1 nm to 2.1 nm were investigated by molecular dynamics simulations. It was found that the transport properties are anisotropic, the axial diffusivity, thermal conductivity, and viscosity are much larger than those in the radial direction. The diffusivity in carbon nanotubes is obviously lower than that of the bulk and it decreases as the diameter of the nanotube decreases. Particularly contrary to the diffusivity, the axial thermal conductivity and shear viscosity in carbon nanotubes is much higher than those of the bulk, and it increases sharply as the diameter of the nanotube decreases. The water molecules ordered in helix inside the (10, 10) single-walled carbon nanotube (SWCN) and the layered distribution was clearly observed.