Self-Similarity and Pattern Selection in the Roughening of Binary Liquid Films

Films of spinodally decomposing binary liquid mixtures show transient wetting of both confining interfaces by one of the phases, and rupture, with characteristic wavelength λc and time τᵣᵤₚₜᵤᵣₑ, leading to flat droplets of the nonwetting phase encapsulated by the wetting phase. Over the entire range of film thicknesses d≈100--3500nm, we find τᵣᵤₚₜᵤᵣₑ∝d^1.01±0.08, indicating film structures that scale self-similarly with d, and find also that λc≈60d^0.97±0.03, the large prefactor suggesting a rupture wavelength which minimizes the interfacial tension of the roughened film.