Issue
EPL
Volume 86, Number 6, June 2009
Article Number 66003
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
DOI http://dx.doi.org/10.1209/0295-5075/86/66003
Published online 01 July 2009
EPL, 86 (2009) 66003
DOI: 10.1209/0295-5075/86/66003

Thin film dynamics with surfactant phase transition

M. H. Köpf, S. V. Gurevich and R. Friedrich

Institute for Theoretical Physics, University of Münster - Wilhelm-Klemm-Straße 9, D-48149 Münster, Germany, EU

m.koepf@uni-muenster.de

received 10 March 2009; accepted in final form 2 June 2009; published June 2009
published online 1 July 2009

Abstract
A thin liquid film covered with an insoluble surfactant in the vicinity of a first-order phase transition is discussed. Within the lubrication approximation we derive two coupled equations to describe the height profile of the film and the surfactant density. Thermodynamics of the surfactant is incorporated via a Cahn-Hilliard–type free-energy functional which can be chosen to describe a transition between two stable phases of different surfactant density. Within this model, a linear stability analysis of stationary homogeneous solutions is performed, and drop formation in a film covered with surfactant in the lower density phase is investigated numerically in one and two spatial dimensions.

PACS
68.15.+e - Liquid thin films.
47.54.-r - Pattern selection; pattern formation.
68.18.Jk - Phase transitions in liquid thin films.

© EPLA 2009