Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: POSTERS Colloids, Nanoparticles and Aggregates

CPP 21.25: Poster

Mittwoch, 27. Februar 2008, 16:00–18:30, Poster A

Stimuli-sensitive micelles from amphiphilic diblock copolymers — •Kordelia Troll¹, Amit Kulkarni¹, Christine M. Papadakis¹, Weinan Wang¹, Peter Müller-Buschbaum¹, Achille M. Bivigou Koumba², and André Laschewsky² — ¹Physikdepartment E13, TU München — ²Institut für Chemie, Universität Potsdam

Amphiphilic diblock copolymers from a hydrophilic, thermosensitive block, poly(N-isopropyl acrylamide) (PNIPAM), and a hydrophobic block, polystyrene, are expected to form micelles in aqueous solution, which are swollen below the lower critical solution temperature (LCST) and collapsed above. We focus on the conformational change of the micellar shell as a function of temperature and the PNIPAM volume fraction.

Two diblock copolymers with different PNIPAM volume fractions were studied at low polymer concentrations in aqueous solution. The temperature behavior was investigated using microcalorimetry and dynamic light scattering. The polymer with a high PNIPAM volume fraction (0.80) form micelles and show a reversible collapse at the expected LCST of ∼31^∘C. The spherical shape of the micelles was confirmed using TEM. The polymer with the low PNIPAM volume fraction (0.29) could not directly be dissolved in water. Aqueous solutions were therefore prepared via dialysis from organic solvents. The size of the aggregates was found to depend strongly on the organic solvent, and no collapse could be detected.