  Spontaneous entry of water molecules inside single-wall carbon nanotubes
(SWCNTs) has been confirmed by both simulations and experiments. Using
molecular dynamics simulations, we have studied the thermodynamics of filling
of a (6,6) carbon nanotube in a temperature range from 273 to 353 K and with
different strengths of the nanotube-water interaction. From explicit energy and
entropy calculations using the two-phase thermodynamics method, we have
presented a thermodynamic understanding of the filling behaviour of a nanotube.
We show that both the energy and the entropy of transfer decrease with
increasing temperature. On the other hand, scaling down the attractive part of
the carbon-oxygen interaction results in increased energy of transfer while the
entropy of transfer increases slowly with decreasing the interaction strength.
Our results indicate that both energy and entropy favour water entry into (6,6)
SWCNTs. Our results are compared with those of several recent studies of water
entry into carbon nanotubes.
