Marangoni effect from density variations in apolar ultrathin films

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 pro. le 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. at film instabilities to scale with the film thickness h(0) to a lower power ( down to n = 0.5) than without this effect.