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Siegel der Universität
Department für Chemie - Arbeitsgruppe Prof. Strey

Zum Grenzflächenverhalten nichtionischer Tenside: Adsorption, Oberflächenkräfte, Filmstabilität

Judith Schlarmann, May 2004

In this study the three non-ionic surfactants n-dodecyl-?-D-maltoside (?-C12G2), hexa-ethyleneglycol-monododecylether (C12E6) and tetraethyleneglycol-monodecylether (C10E4) were investigated. The surface excess concentration ? and the cmc values, which were determined from static surface tension measurements, provide information about the surface activity of these surfactants. Measurements of the dynamic surface tension were used to investigate the adsorption kinetics and to calculate the diffusion coefficient D. The disjoining pressure P in free-standing thin liquid films stabilised by the above mentioned surfactants as a function of the film thickness h were investigated with a thin film pressure balance (TFPB). Thereby, the charge of the water-air-interface and its interference with the surfactant concentration was of special interest. In addition thin liquid films between two hydrophobic solid surfaces were investigated with the MASIF (Measurement and Analysis of Surface Interaction Forces) technique. The influence of fixed charges at the water-glass-interface and the interactions between two uncharged surfaces were compared with the results obtained with the TFPB. Last but not least, macroscopic foams stabilised by C12E6 were studied with the foam pressure drop technique in order to correlate the properties of the foam with those of the free-standing thin liquid films.