  Thermally driven nanotube nanomotors provide linear mass transportation
controlled by a temperature gradient. However, the underlying mechanism is
still unclear where the mass transportation velocity in experiment is much
lower than that resulting from simulations. Considering that defects are common
in fabricated nanotubes, we use molecular dynamics simulations to show that the
mass transportation would be considerably impeded by the potential barriers or
wells induced by the defects, which provides a possible picture to understand
the relative low value at microscopic level. The optimal structure and the
factors which would affect the performance are discussed. The result indicates
considering defects is helpful in designing nanotube nanomotor and other new
nanomotor-based devices.
