Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: Poster: Colloids and Complex Liquids

CPP 16.22: Poster

Dienstag, 27. März 2012, 18:15–20:45, Poster A

Dynamic percolation in microemulsions based on anionic and nonionic surfactants — •Andreas Bischof, Christina Lederle, Andreas Weber, Tinka Spehr, and Bernd Stühn — TU Darmstadt, Experimentelle Physik kondensierter Materie, Germany

We study structure and dynamics of water-in-oil microemulsions with a focus on dynamics percolation phenomenon. In order to do this, we use dielectric spectroscopy. Comparing microemulsions based on different surfactants, we see a significant change in the percolation behaviour. We compare water-in-oil microemulsions based on anionic (AOT: Dioctyl sodium sulfosuccinate) and nonionic (i.e. C12E4: Pentaethylene glycol monododecyl ether) surfactants. Both display the known phenomenon of percolation that manifests itself in a steep increase of conductivity changing composition or temperature. We focus on the droplet phase and the temperature dependent behaviour to estimate the percolation temperature Tp. The percolation transition is observed with increasing temperature for ionic surfactants and decreasing temperature for nonionic surfactants. Moreover in the case of nonionic surfactant based microemulsions we study the effect of addition of salts. We compare results from dielectric spectroscopy to structural findings by means of small angle x-ray scattering (SAXS).