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Siegel der Universität
Department für Chemie - Arbeitsgruppe Prof. Strey

Lyotrope Mesophasen in Nachbarschaft von hocheffizienten Mikroemulsionen

Christian Frank, June 2004

Since many years the properties of microemulsions have been subject of intensive research. Recently, it was found that amphiphilic block copolymers increase the efficiency of microemulsions drastically. The same effect can be used to induce or suppress lyotropic mesophases of variable length scale. One can adjust the domain size by varying the surfactant concentration, whereas the extend of the liquid crystalline areas is controlled by the size and concentration of the amphiphilic blockcopolymer. The main focus of this work is to determine the structure of the observed lyotopic mesophases by means of optical inspection, 2H ? NMR spectroscopy and small angle neutron scattering (SANS). The quadrupolar 2H ? NMR spectroscopy permits an investigation of the anisotropic mesophases, as well as to determine quantitatively the temperature range and number of coexisting phases. The additional use of scattering methods like SANS is necessary to investigate isotropic cubic phases. By varying the temperature, it is possible to determine cubic, hexagonal, lamellar and the corresponding invers states in one system. A further aspect of this work is to transfer the efficiency boosting effects on silicon oil microemulsions.