Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.30: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

SANS study of PEP-PEO diblock copolymer micelles as "tunable" star polymers — •Marco Laurati, Jörg Stellbrink, Lutz Willner, Reidar Lund, and Dieter Richter — Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany.

Regular star polymers have recently been introduced as a new class of ultra soft colloids. The phase diagram of this system has been derived by theory and Monte Carlo simulations.The investigation of the phase behavior of real star polymers presents practical difficulties: i) synthetic limitations prevent refined aggregation number adjustement; ii) the polydispersity in the arm number suppresses crystalline phases.
Very recently we started to use PEP1k-PEO20k star-like micelles as “tunable” model system for unimolecular star polymers. This block copolymer can be easily prepared in desired molecular weight and composition. The large asymmetry of the blocks guarantees the desired star-like behavior. In water the micelles can be regarded as kinetically frozen since unimer exchange does not exist as observed by time resolved SANS experiments. The micellar arm number can be tuned by addition of dimethylformamide (DMF) to the solvent.
We present the structural properties of the micelles obtained from SANS experiments, as a function of micellar concentration. In particular we compare the core-core partial structure factors derived from measurements with theory predictions. Special attention has been paid to the investigation of the concentration range around the overlap concentration c*, where liquid-solid transition is expected.