Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 2: Focus: Amphiphilic Systems II

CPP 2.2: Topical Talk

Montag, 23. März 2009, 14:30–15:00, ZEU 222

Structural Transitions in Self-aggregating Systems Studied by Means of the Stopped-flow Technique — •Michael Gradzielski — Stranski-Laboratorium, Institut für Chemie, Technische Universität Berlin, Germany

Typically self-aggregating structures are highly dynamic species where characteristic times for structural reorganisations may range from *s to weeks. Such structural changes can be triggered by mixing with other surfactants, polymers, or solubilisates. In our experiments rapid mixing was done by the stopped-flow technique and followed with turbidity, conductivity, and fluorescence detection or by coupling it to high-flux SANS/SAXS instruments which allows to obtain detailed structural information with a time-resolution of 5-50 ms. Using this method a variety of different structural transitions has been investigated, e. g. the formation of unilamellar vesicles by admixing oppositely charged surfactant or a cosurfactant, solubilisation processes in microemulsions, or the formation of interpolyelectrolyte complexes (IPECs) by admixing oppositely charged polyelectrolytes with charged block copolymer micelles. These processes were followed in structural detail and especially with respect to intermediate, non-equilibrium structures involved. These dynamic processes can be described by invoking simple elementary steps and analysing growth processes for instance in terms of Ostwald ripening or coalescence processes. In particular, in our experiments we are interested in how such intermediate structures differ from the final states and allow for a control of the structures formed.