Dresden 2017 – wissenschaftliches Programm
CPP 18.7: Poster
Montag, 20. März 2017, 18:30–21:00, P1C
Influence of poly(ethylene glycol) chain length on ionic w/o microemulsions — •Ann-Kathrin Grefe, Alexander Matt, and Bernd Stühn — Institut für Festkörperphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
Microemulsions are thermodynamically stable mixtures of a hydrophilic and a hydrophobic component, stabilized by surfactants. There have been extensive studies in order to determine how the presence of foreign molecules influences the behaviour of a microemulsion.
We study the droplet phase of water-in-oil microemulsions containing the anionic surfactant dioctyl sulfosuccinate (AOT). The droplets are loaded with the water soluble polymer poly(ethylene glycol), which is expected to dissolve in the water droplets and shows attractive interactions with the surfactant shell . We investigate different molecular weights of PEG ranging from 200 g/mol to 12000 g/mol. In doing so, we are able to differentiate between the influence of chain length and number of hydroxy groups. The influence of the polymer on percolation and phase separation temperature TP and TC is examined. To determine TP and TC we use dielectric spectroscopy at a frequency of 10 kHz utilizing the steep increase in conductivity as the percolation temperature is approached. In addition, the temperature dependent radii of the water droplets are investigated via small angle x-ray scattering, using the pronounced electron density contrast of the surfactant shell. By combining the results we can calculate the bending modulus of the surfactant shell.
 R. Wipf et al., Colloid Polym Sci 288, 589-601 (2010)