Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 28: Nano structures

CPP 28.1: Talk

Tuesday, March 8, 2005, 15:15–15:30, TU C243

Studying Surfactant Self-Assembly by Fluorescence Correlation Spectroscopy — •Heiko Zettl¹, Moshe Gottlieb², and Georg Krausch¹ — ¹Physikalische Chemie II, Universität Bayreuth — ²Chemical Engineering Department, Ben-Gurion University, Beer Sheva, Israel

The formation of micelles of SDS, AOT, CTAC, and C12E5 have been studied by Fluorescence Correlation Spectroscopy (FCS). From FCS experiments the translational diffusion coefficient, hydrodynamic radii, and the critical micelle concentration (cmc) is determined. As label for our experiments we use several commercial dyes. The detected CMC is similar to values reported in literature. The size of the detected micelles is bigger than the reported values. The reason for this difference may be the additional dye molecule. The results show that there is no need to synthesize labelled surfactant molecules for determination of the CMC of surfactants by FCS. Moreover, our results indicate that the charge of the surfactant head group and the polarity of the dye molecules need to be adapted for successful CMC determination. In contrast to classical methods for CMC determination like light scattering or conductivity measurements FCS has the ability to follow the process of micelle formation. Already below the classical CMC we see the formation of micelles and can follow the increase of the number of micelles with increasing surfactant concentration.