Figure 3.

Schematic illustration of a liquid drop on a smooth solid surface surrounded by a vapor phase. The interfacial energies associated with the 3 phases include solid–liquid, ${\gamma }_{SL}$, solid–vapor, ${\gamma }_{SV}$, and liquid–vapor, ${\gamma }_{LV}$. The WCA, θ, is measured at the 3-phase contact line, P, from the solid–liquid interface to the liquid–vapor interface within the liquid phase.