Regensburg 2010 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: Poster: Structure and Dynamics of Responsive Hydrogels
CPP 10.5: Poster
Monday, March 22, 2010, 16:30–18:00, Poster C
Structure and dynamics of thermoresponsive blockcopolymer gels — •Joseph Adelsberger1, Andreas Meier-Koll1, Weinan Wang1, Achille M. Bivigou-Koumba2, André Laschewsky2, Thomas Hellweg3, Olaf Holderer4, Vitaliy Pipich4, Peter Busch4, Peter Müller-Buschbaum1, and Christine M. Papadakis1 — 1TU München, Physik-Department E13, Garching — 2Universität Potsdam, Institut für Chemie — 3Universität Bayreuth, Physikalische Chemie I — 4Jülich Center of Neutron Science, Garching
Thermoresponsive polymer gels display strong changes in volume when heated above the lower critical solution temperature (LCST). Therefore they are interesting candidates for applications in ultrafiltration or as drug delivery systems. We investigate triblock copolymers consisting of two hydrophobic polystyrene (PS) end blocks and a hydrophilic poly(N-isopropyl acrylamide) (PNIPAM) middle block. In aqueous solution they form core-shell micelles or micellar networks. The structure of the micelles and their correlation is determined using small-angle neutron scattering (SANS) and dynamic light scattering [1]. The micellar radius shows a sudden decrease at the LCST, i.e. the formerly hydrophilic shell shrinks. Above the LCST, the collapsed micelles form clusters, and water is released. The kinetics of the collapse transition is investigated in time-resolved SANS measurements. Neutron spin-echo spectroscopy is used to study the segmental dynamics of the hydrophilic block. The intermediate scattering function displays the fast PNIPAM segmental motion and the slow micellar diffusion.
[1] A. Jain, C. M. Papadakis et al., Macromol. Symp., accepted