Dewetting Revisited: New Asymptotics of the Film Stability Diagram and the Metastable Regime of Nucleation and Growth of Dry Zones

Abstract

Stability properties of a nonwetting film are discussed. Assuming a general form of the disjoining pressure, accurate asymptotic formulas for the upper thickness range of the film instability/metastability are derived. This analysis is applied to two particular cases: a nonionic liquid film with the (m, n) power form of the disjoining pressure and an ionic liquid film with an exponentially decaying electrostatic part of the disjoining pressure. The metastable regime of dewetting is considered, and an expression for the critical radius of a hole is derived. A new Fokker–Planck kinetic model of metastable dewetting, applicable at early stages of the process, is developed. It yields a relationship between the number of viable holes (per unit area and unit time) moving in steady-state regime to the supercritical part of the “embryo size space” and the equilibrium number of “critical” holes determined from thermodynamics. The dynamics of metastable dewetting is quantitatively described in terms of the surface fraction of holes in the film. Continuous dynamic models of the metastable dewetting applicable in the entire range of times have to include the thermal noise, as proposed by V. S. Mitlin (1994, Colloids Surf. A89, 97).