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Siegel der Universität
Department für Chemie - Arbeitsgruppe Prof. Strey

Der Schlüssel zum Verständnis von Mikroemulsionen aus Zuckertensiden: Die interne Grenzfläche

Karsten Kluge, May 2000

The properties of quaternary microemulsions consisting of water n-octane b-C8G1n-octanol are examined. Knowing the general properties of the quaternary system watern-octaneC8E5n-octanol, C8E5 has been replaced by b-C8G1. Since the phase behavior and the microstructure of microemulsions depend mainly on the curvature of the interfacial film separating the oil and the water domains, the curvature of the film is tuned by the composition of the film at constant temperature and pressure. It is shown here for the first time by simultaneous phase behavior, SANS and NMR measurements which quantitative correlation between the curvature and the composition of the interfacial film exists. Despite the chemical differences of the components of the microemulsions examined so far it is demonstrated that all these systems are equivalent from a theoretical point of view, i.e. they follow common scaling laws. The behavior of quaternary, temperature-insensitive microemulsions based on alkyl glucosides can be mapped onto that of related ternary systems, which exhibit a temperature dependent curvature of the film. Thus, temperature and alcohol content in the interfacial film are important tuning parameters for the curvature, which may be chosen to formulate microemulsions with desired properties in practical applications.