Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Dynamics
CPP 18.14: Poster
Dienstag, 12. März 2013, 18:15–20:15, Poster C
Cononsolvency of PNIPAM in water/methanol mixed solutions — •Konstantinos Kyriakos1, Martine Philipp1, Joseph Adelsberger1, Sebastian Jaksch1, Anna Miasnikova2, André Laschewsky2, Isabelle Grillo3, Peter Müller-Buschbaum1, and Christine M. Papadakis1 — 1TU München, Physikdepartment, Physik weicher Materie, Garching — 2Universität Potsdam, Fakultät für Chemie, Potsdam-Golm — 3Institut Laue-Langevin, Grenoble, France
Thermoresponsive polymer poly(N-isopropyl acrylamide) (PNIPAM) exhibits a lower critical solution temperature (LCST) of 32 oC in aqueous solution. Upon the addition of a second polar solvent, e.g. methanol, a miscibility gap appears, which is termed as cononsolvency. Diblock copolymers consisting of a long PNIPAM block and a short polystyrene block, e.g. P(S-b-NIPAM), form micelles with a thermoresponsive shell [1].
We report here on a stopped-flow experiment with time-resolved SANS on an aqueous solution of a PNIPAM homopolymer or a P(S-b-NIPAM) diblock copolymer to which methanol was added. This resulted in a collapse transition of the linear chains or the micellar shell, respectively, and on the subsequent aggregation. For both systems the aggregation path and the final size of the formed aggregates depend on the mixing ratio. Interestingly, the size of the formed aggregates is much bigger for the homopolymer compared to the diblock copolymer.
[1] J. Adelsberger, A. Laschewsky, P. Müller-Buschbaum, C.M. Papadakis et al., Colloid Polym. Sci. 2011, 289, 711