INSTITUTE OF PHYSICS PUBLISHING JOURNAL OF PHYSICS: CONDENSED MATTER J. Phys.: Condens. Matter 15 (2003) S331–S336 PII: S0953-8984(03)55156-6 Self-destruction and dewetting of thin polymer films: the role of interfacial tensions G¨ unter Reiter 1,3 , Rajesh Khanna 1,4 and Ashutosh Sharma 2 1 Institut de Chimie des Surfaces et Interfaces, CNRS-UHA, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse Cedex, France 2 Department of Chemical Engineering, Indian Institute of Technology at Kanpur, 208 016, India E-mail: G.Reiter@uha.fr Received 23 October 2002 Published 16 December 2002 Online at stacks.iop.org/JPhysCM/15/S331 Abstract We present real-time optical microscopy observations of the pattern evolution in self-destruction and subsequent dewetting of thin polymer films based on experiments with polydimethylsiloxane films sandwiched between silicon wafers and aqueous surfactant solutions. A clear scenario consisting of four distinct stages has been identified: amplification of surface fluctuations, break- up of the film and formation of holes, growth and coalescence of holes, and droplet formation and ripening. Besides a linear dependence on film viscosity and surface tension, the time τ for film rupture varied significantly with film thickness h (τ ∼ h 5 ), as expected from theory. While the role of long-range forces is dominant only in the first stage, the later stages are controlled by the combination of interfacial tensions resulting in the contact angle characterizing the three-phase contact line. During the first stage, the characteristic distance of the pattern remains constant, represented by a time-independent wavevector. In all subsequent stages, this wavevector decreases with time as a consequence of hole opening, coalescence, and ripening on droplets. The later stages of evolution are a function of the contact angle at the three-phase contact line. Only a clear distinction between stages before and after film break-up allows a correct interpretation of the observed pattern evolution in unstable thin films. (Some figures in this article are in colour only in the electronic version) The destruction and pattern formation in thin fluid films is of central importance in many technological applications as well as in a variety of physical and biological thin-film phenomena. The general contours of the mechanics and thermodynamics of thin-film instability have emerged during the last 50 years [1–9]. Initial surface fluctuations at the 3 Author to whom any correspondence should be addressed. 4 Present address: Department of Chemical Engineering, Indian Institute of Technology at New Delhi, 16, India. 0953-8984/03/010331+06$30.00 © 2003 IOP Publishing Ltd Printed in the UK S331