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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.71: Poster

Donnerstag, 30. März 2006, 16:00–18:00, P1

Conductivity Measurements on Water in Oil Microemulsions — •Robert Wipf, Thomas Blochowiscz, Gustav Nyström, and Bernd Stühn — Institute of Condensed Matter Physics, Technical University Darmstadt, D-64289 Darmstadt

Water-in-oil microemulsions are thermodynamically stable mixtures of waterdroplets in a continuous oil phase. The water droplets are stabilized by a monomolecular surfactant layer. Surfactant molecules have a polar, hydrophilic headgroup and an apolar, lipophilic tail. The investigated microemulsion consists of water and decane with sodium bis(2-ethylhexyl)sulfosuccinate (AOT) as surfactant. Structure and dynamics of this system is well characterized by small-angle-X-ray and dynamic light scattering measurements. The conductivity of such systems shows a steep increase with volume fraction of droplets or temperature increasing over a certain critical value. This behavior can be attributed to a dynamic percolation phenomenon.[1]

Adding an amphiphilic triblock copolymer to a microemulsion leads to an interconnection of the droplets and thus to generation of a transient network. Here we will present our conductivity measurements on pure microemulsions and microemulsions containing polymer. We performed frequency and temperature dependent measurements in a range of 15^∘C to 35∘C and 10⁻²Hz to 10⁶Hz respectively. First we characterized the percolation transition in pure microemulsions. Then we investigated the influence of increasing polymer content on the ion transport and relaxation in the microemulsion was investigated.

[1] H. Kataoka et al.: J. Phys. Chem. B 2003, 107, 12542-12548