In order to calculate the probabilities of
nucleation of liquid droplets at different types of site on a solid surface,
the properties of embryonic droplets which may exist in complete thermodynamic
equilibrium at those sites must be known. The general properties of liquid
embryos formed on a plane solid surface, or at lines or points of intersection
of plane solid surfaces, are considered. It is shown that, although an edge
free energy associated with the boundary line may substantially affect the properties
-of embryos at small contact angles, the effect is probably not large, for
embryos of the sizes of interest, when the contact angle is larger than about π/4.
The areas, volumes, total surface free
energies, and free energies of formation are found for embryos at these sites
as functions of the contact angle, any edge free energies being neglected. The
extension to the formation of bubbles at plane solid surfaces in a pure liquid
is indicated. The results are applied in a following paper to the kinetics of
condensation of a vapour at an imperfect crystalline surface.
Coalescence of droplets on micro-structure patterned hydrophobic planar solid surfaces
