Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 45: P10: Colloids and Complex Liquids

CPP 45.7: Poster

Wednesday, March 18, 2015, 10:00–13:00, Poster A

Increasing the bending modulus of AOT based microemulsions by the addition of polymer — •Ann-Kathrin Grefe, Björn Kuttich, and Bernd Stühn — Experimental Condensed Matter Physics, TU Darmstadt, Germany

Being a highly versatile system, microemulsions are applied in many different fields from medical science to oil production. In order to make such implementations accessible, an extensive understanding of the interactions in microemulsions, especially in the presence of additives, is essential. Microemulsions with added polymers represent a suitable simplified model system to study these interactions.

This work focuses on the analysis of AOT based w/o microemulsions in the droplet phase, modified by the water soluble polymer polyethylene glycol (PEG). The polymer is confined to the water core of the droplets where it is expected to adsorb at the surfactant shell. Due to the adsorption the bending modulus of the shell changes, which in turn affects the phase diagram of the microemulsion.

Samples with different amounts of polymer are examined by dielectric spectroscopy to find their percolation and phase separation temperatures. Temperature resolved small angle X-ray scattering allows the determination of the water droplet sizes. In doing so, a dependence of the droplet radius on the molar ratio of water and surfactant as well as on the temperature is found and quantified. Both are significantly influenced by the presence of polymer. Combining dielectric and scattering experiments the bending modulus of the surfactant shell can be deduced and a stiffening of the shell due to the polymer is found.