Spinodal-like dewetting of thermodynamically-stable thin polymer films
Unité de Physique et de Chimie des Hauts Polyméres (POLY) and Research Centre in Micro- and Nanoscopic Materials and Electronic Devices (CeRMiN), Université catholique de Louvain,, Croix du Sud 1,, 1348 , Louvain-la-Neuve,, Belgium
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Energetic considerations indicate that long-range Van der Waals forces stabilize thin polystyrene (PS) films against height fluctuations on silicon substrates. Nevertheless, we report here on the amplification of capillary waves of specific wavelengths for 15 nm thick PS films on silicon, ultimately leading to dewetting in a “spinodal-like” process. However, the temporal dependence of the wavelength of the growing instability does not agree with the “classical” spinodal dewetting mechanism. Therefore, this phenomenon is ascribed to the existence of “structural” forces resulting either from the restructuring of the films or from density variations within the films during annealing, in accordance with recent theoretical treatments. The process is shown not to be limited to polystyrene films, which indicates the generality of our findings.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2003