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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: POSTERS Amphiphilic Systems

CPP 11.5: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Phase Separation Dynamics in (Pseudo)Binary Mixtures — •Ebie M. Sam, Guenter K. Auernhammer, Yumino Hayase, and Doris Vollmer — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

We investigated the phase separation dynamics in a pseudo-binary mixture of C4E1 and water, doped with a few percent of decane. The system phase separates under heating, as it crosses the binodal. Cooling rates of 1-20 K/h were used. We used sample cells with a diameter of 15cm and a height of around 1 cm, resulting in an aspect ratio of approx 15. Video microscopy of scattered light was utilized to track the dynamics of the phase separation. A temperature gradient was induced, with the upper side hotter. Patterns, whose sizes are comparable to the cell-thickness, were observed just after the initial clouding. Due to the sign of the temperature gradient their origin cannot be attributed to the Rayleigh-Benard convection. Possibly these patterns could be formed by the latent heat during the droplet-formation in the system. This is sufficient to induce a convective flow. A similar explanation could be given to the patterns we observed in the methanol-hexane binary system, which phase separates under cooling.