Figure 1
From: Critical Dipole Length for the Wetting Transition Due to Collective Water-dipoles Interactions
Introduction to the model system and its wetting behaviour.
(a,b) Structure of the model surface with l = 0.142 nm and 0.262 nm at q = 1.0 e together with snapshots of some water molecule. The green and blue triangles represent the atoms on the solid surface with positive charges and negative charges, respectively. The oxygen and hydrogen atoms of the water molecules are shown by (bright or soft) red and white spheres. The oxygen atom of a water molecule with one OH bond pointing downward is shown by soft red. (c) Contact angle discrepancy (θ0−θq) with respect to the dipole length (l) for the charge (q) 0.2 e (black), 0.4 e (red), 0.6 e (blue), 0.8 e (green) and 1.0 e (magenta). θq and θ0 are the contact angles of the liquid droplets on the surface with a charge of q and without any charge, respectively. The saturation values of θ0−θq increases from ~102° for l = 0.242 nm to ~130° for l = 0.482 nm due to the modification of the lattice length, which correspond to complete wetting of the surface (θq = 0). (d) Critical lengths for some typical surfaces of binary compound crystals. Here, the critical length is defined as the dipole length below which the contact angle discrepancy (θ0−θq) is less than 15° for all q value in the interval of [0, 1.0 e], or in the interval of [0, 0.4 e], denoted by lC and lC0.4 and shown by black and red columns, respectively. The first surface type is the structure shown in (a,b). The other surface types, increasing from 2 to 6, corresponds to the square, rhombic and rectangle lattice, (110) surface of a face-centered cube and (110) surface of a body centered tetragonal, respectively (see Fig. S1 in Supplementary Information).
