A systematic molecular dynamics study shows that the contact angle of a water droplet on graphite changes significantly as a function of the water−carbon interaction energy. Together with the observation that a linear relationship can be established between the contact angle and the water monomer binding energy on graphite, a new route to calibrate interaction potential parameters is presented. Through a variation of the droplet size in the range from 1000 to 17 500 water molecules, we determine the line tension to be positive and on the order of 2 × 10-10 J/m. To recover a macroscopic contact angle of 86°, a water monomer binding energy of −6.33 kJ mol-1 is required, which is obtained by applying a carbon−oxygen Lennard-Jones potential with the parameters εCO = 0.392 kJ mol-1 and σCO = 3.19 Å. For this new water−carbon interaction potential, we present density profiles and hydrogen bond distributions for a water droplet on graphite.

A conversion error has been detected in the analysis of the line tension (Figure 4); the units of the abscissa axis should be Å -1 . The subsequent analysis of the line tension on page 1349 is therefore in error by a factor of 10. Thus, the magnitude of the line tension can be estimated from the slopes of the fits in Figure 1, compare eq 3, which are -0.94 (case 14), -3.33 (case 1), and -3.72 Å (case 10), respectively. For a surface tension of water of γ LV ) 72 mN/m, the line tension τ is found to be 0.7 × 10 -11 (case 14), 2.4 × 10 -11 (case 1), and 2.7 × 10 -11 J/m (case 10). This error has no implication for the remaining analysis and conclusions presented in the paper. A corrected version of Figure 4 is given below.

No abstract

We study the behavior of water droplets confined in a carbon nanotube by means of parallel molecular dynamics simulations. We report radial density profiles, radial hydrogen bond distributions, and contact angles for tube radii ranging from 12.5 to 37.5 Å and for droplets containing up to 4632 water molecules. Our results indicate nonwetting behavior of the pristine CNT at room temperatures.

No abstract