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Siegel der Universität
Department für Chemie - Arbeitsgruppe Prof. Strey

Neuartige Nanostrukturen im Lichte von Neutronen und Photonen: Giant microemulsions

Stefan Müller, Februar 2003

By using amphiphilic blockcopolymers as efficiency boosters it was possible to produce highly efficient microemulsions consisting of equal amounts of water and oil. These highly efficient microemulsions contain less than 3 wt.%, sometimes even less than 1 wt.%, surfactant and polymer. As a consequence of the low surfactant content, the size of the microemulsion domains can be as large as 0.5 µm. Although these efficient microemulsions scatter light strongly and are turbid like emulsions, they are still thermodynamically stable. The strong scattering intensities which occur both at light and neutron scattering were minimized by adjusting the refractive indices as well as the scattering length densities between the water and oil domains (double contrast variation). Thus it was possible to directly compare static light scattering (SLS) and small angle neutron scattering (SANS). For the first time a highly diluted iridescent lamellar phase was found beneath the highly efficient microemulsion of the pseudo ternary systems. The colors of the iridescent phase can be observed at large scattering angles so that the spacing between the lamellars was characterized by backscattering of visible light.