Effect of the Carbon-Nanotube Length on Water Permeability

Effect of the carbon nanotube （CNT） channel length on the water flow through the CNT is studied using molecular dynamics simulations. The water flow is found to decay with the channel length （-1/N^2.3, N is the number of carbon rings along the nanotube axis）, much faster than that predicted by a previous continuous-time random walk （CTRW） model （-1/N）. This unexpected decay rate of flow is found to result from the weakening of the correlation of the concerted motion of the water molecules inside the ONT. An improved CTRW model is then proposed by taking into account of this effect. Meanwhile, the diffusion constant of water molecules inside CNTs with various lengths is found to be relatively invariant, which results in a relatively constant hopping rate.     

High density gas state at water/graphite interface studied by molecular dynamics simulation

In this paper molecular dynamics simulations are performed to study the accumulation behaviour of N2 and H2 at water/graphite interface under ambient temperature and pressure. It finds that both N2 and H2 molecules can accumulate at the interface and form one of two states according to the ratio of gas molecules number to square of graphite surface from our simulation results： gas films （pancake-like） for a larger ratio and nanobubbles for a smaller ratio. In addition, we discuss the stabilities of nanobubbles at different environment temperatures. Surprisingly, it is found that the density of both kinds of gas states can be greatly increased, even comparable with that of the liquid N2 and liquid H2. The present results are expected to be helpful for the understanding of the stable existence of gas film （pancake-like） and nanobubbles.     

Large Slip Length over a Nanopatterned Surface

A thermodynamic method is employed to analyse the slip length of hydrophobic nanopatterned surface. The maximal slip lengths with respect to the hydrophobicity of the nanopatterned surface are computed. It is found that the slip length reaches more than 50 μm if the nanopatterned surfaces have a contact angle larger than 160°. Such results are expected to find extensive applications in micro-channels and helpful to understand recent experimental observations of the slippage of nanopatterned surfaces.