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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Micro and Nanofluidics I

CPP 26.10: Vortrag

Mittwoch, 24. März 2010, 16:30–16:45, H39

Instability of confined water films between elastic surfaces — •Sissi de Beer, Dieter 't Mannetje, Sietske Zantema, and Frieder Mugele — University of Twente, Enschede, the Netherlands

We investigated the dynamics of nanometer thin water films at controlled ambient humidity adsorbed onto two atomically smooth mica sheets upon rapidly approach of the two surfaces into contact. Using a Surface Forces Apparatus (SFA) in the imaging mode, we found that the water films break up into a distribution of small drops with a typical thickness of few nanometers and a characteristic lateral size and spacing of several micrometers. While the characteristic length of the drops is found to be independent of the ambient humidity, the characteristic time of the break-up decreases from ~1s to 0.01s with increasing humidity. The existence, of characteristic length and time scales shows that this break-up is controlled by an instability rather than a * for SFA experiments conventional * nucleation and growth mechanism. These findings cannot be explained by a dispersion-driven instability mechanism like e.g. spinodal dewetting. In contrast, a model incorporating the elastic energies for the deformation of both the mica sheets and the underlying glue layer (i.e. wrinkling) slowed down by the hydrodynamic resistance correctly reproduces the scaling of the characteristic length and time with humidity.