Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Elastomers and Gels

CPP 14.8: Vortrag

Dienstag, 15. März 2011, 12:30–12:45, ZEU 114

Kinetics of structural changes in concentrated thermoresponsive blockcopolymer solutions — •Joseph Adelsberger¹, Ezzeldin Metwalli¹, Alexander Diethert¹, Achille Bivigou-Koumba², André Laschewsky², Isabelle Grillo³, Peter Müller-Buschbaum¹, and Christine M. Papadakis¹ — ¹TU München, Lehrstuhl für funktionelle Materialien, Garching — ²Universität Potsdam, Institut für Chemie — ³Institut Laue-Langevin, Grenoble

Thermoresponsive polymers display strong changes in volume when heated above the lower critical solution temperature (LCST). Therefore they are interesting candidates for applications in ultrafiltration, in sensors or as drug delivery systems. We study triblock copolymers consisting of two hydrophobic polystyrene end blocks and a hydrophilic poly(N-isopropyl acrylamide) middle block. In aqueous solution they form core-shell micelles or micellar networks [1]. In order to elucidate the structural changes, occuring after rapid heating above the LCST, we have performed time-resolved small-angle neutron scattering experiments with measurement times down to 0.1 s at D22 at ILL in Grenoble. The micellar radius shows a sudden decrease immediately after the LCST is crossed, i.e. the formerly hydrophilic shell shrinks and releases water. Moreover collapsed micelles form small fractal aggregates, which become denser and grow to big clusters.
A. Jain, C. M. Papadakis et al., Macromol. Symp. 291-292 (2010), 221; J. Adelsberger, C. M. Papadakis et al., Macromolecules 43 (2010), 2490