Marangoni effect from density variations in apolar ultrathin films

¹ Complex Fluids, Van 't Hoff Institute for Molecular Sciences University of Amsterdam - Nieuwe Achtergracht 166 1018 WV Amsterdam, The Netherlands
² Microgravity Research Center, Service Chimie Physique EP Université Libre Bruxelles - Av. F. D. Roosevelt 50, 1050 Brussels, Belgium
³ Laboratoire de Physique de la Matière Condensée, Université Claude Bernard Lyon 1 et CNRS - Domaine Scientifique et la Doua, 69622 Villeurbanne Cedex, France

Received: 11 August 2005
Accepted: 30 March 2006

Abstract

Recently it was demonstrated that the presence of density variations in thin films can induce interactions that cause destabilization and rupture of thin films. In apolar films the surface tension is also dependent on the film density, so that a lateral variation in film density creates a surface tension gradient, thus producing a Marangoni effect. We include this effect in the hydrodynamic equation governing the evolution of the film profile and perform an analysis of the stability of the film. In particular, inclusion of the Marangoni effect causes the characteristic length scale of the initial flat film instabilities to scale with the film thickness h₀ to a lower power (down to ) than without this effect.