Stability of Voids Formed in Cavities at Liquid-Solid Interfaces.
Stability of Voids Formed in Cavities at Liquid-Solid
Bullard, J. W.
Journal of Colloid and Interface Science, Vol. 276, No.
1, 188-196, 2004.
voids; stability; interfaces; wetting; thermodynamics;
A thermodynamic model is developed of the free energy of
gas-filled voids formed within cavities on solid
surfaces covered by a liquid. Capillary effects are
assumed to be the only important contributions to the
free energy, and expressions are derived for the free
energy of the system as a function of the void size, the
relative surface free energy densities involved, and the
geometry of the cavity. The results of the model are (1)
construction of a stability diagram that maps the most
stable void configuration versus the wetting properties
of the various solid surfaces involved, and (2) rough
estimates of the work required to liberate a void of a
given size and position. The model can give qualitative
insight into the stability of coating defects on uneven
surfaces, and also can be used to prescribe possible
surface treatments for educing the work required to
remove voids from the system.