DOI 10.1007/s1010500e0002 EPJdirect E2, 1–9 (2000) EPJdirect electronic only c  EDP Sciences 2000 c  Societ` a Italiana di Fisica (SIF) 2000 c  Springer-Verlag 2000 The ABC of pattern evolution in self-destruction of thin polymer films Rajesh Khanna 1* , Ashutosh Sharma 2 , G¨ unter Reiter 1† 1 Institut de Chimie des Surfaces et Interfaces, CNRS, 15, rue Jean Starcky, B.P. 2488, 68057 MULHOUSE Cedex, FRANCE 2 Department of Chemical Engineering, Indian Institute of Technology at Kanpur, INDIA–208 016 Received: 17 Apr 2000 / Accepted: 6 Sep 2000 / Published online: 22 Sep 2000 Abstract. We present the first real time observation of the pattern evolution in self- destruction of thin polymer films based on experiments with polydimethylsiloxane films sandwiched between silicon wafers and aqueous surfactant solutions. Four distinct stages of pattern evolution have been identified: (A) amplification of surface fluctu- ations, (B) breakup of the film and formation of holes, (C) growth and coalescence of holes and, (D) droplet formation and ripening. Only one of these stages, A, is unique to self-destruction of thin films as stages B, C and D are also present in nucleation in- duced dewetting of the film. As similar looking undulating patterns characterize stages A and C, it becomes imperative to have a full temporal evolution of the pattern to identify different stages and the likely mechanism of film breakup. PACS: 47.20.-k, 68.15.+e, 68.10.-m The destruction and pattern formation in thin fluid films is of central impor- tance in many technological applications (e.g., wetting, adhesion, heterogenous nucleation, colloids, membrane-morphology, dry eye syndromes, opto-electronic devices) as well as in a variety of physical and biological thin film phenomena (e.g., polymeric and metal coatings, foams, emulsions, flotation). The general contours of the mechanics and thermodynamics of thin film instability have emerged during the last fifty years [1, 2, 3, 4, 5]. Initial surface fluctuations at the free surface of an initially rather uniform thin film get amplified sponta- neously whenever the second derivative of the excess intermolecular free energy (per unit area) with respect to the local film thickness is negative and their wavelength is larger than a critical wavelength. This amplification eventually leads to the dewetting of the underlying substrate in the form of dry patches [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]. Dewetting can also be initiated by formation of isolated circular holes due to nucleation by defects, dust * Present address: Department of Chemical Engineering, Indian Institute of Technology at Delhi, India † e-mail: G.Reiter@univ-mulhouse.fr http://link.springer.de/link/service/journals/10105/index.htm