Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 27: Poster: (Hydrogels) and Elastomers
CPP 27.10: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
Switching Behavior of Thermoresponsive Poly(2-oxazoline) Copolymers — •Sebastian Jaksch1, Stephan Salzinger2, Stephan Huber2, Joseph Adelsberger1, Peter Busch3, Rainer Jordan4, and Christine M. Papadakis1 — 1TU München, Physikdepartment, Physik der weichen Materie, Garching — 2TU München, Department Chemie, Lehrstuhl für Makromolekulare Chemie, Garching — 3JCNS-FRM II, Garching — 4TU Dresden, Department Chemie, Professur für Makromolekulare Chemie, Dresden
Thermoresponsive polymers in aqueous solution exhibit a strong change in solubility and volume when heated above their cloud point. Especially interesting polymers of this class of materials are poly(2-oxazoline)s (POx) which are biocompatible. We investigate poly[(iso-propyl-2-oxazoline)-grad-(n-nonyl-2-oxazoline)] gradient copolymers where the fraction of the hydrophic nonyl moieties is varied. These moieties are found to lower the cloud point from 41∘C to 23∘C. In order to elucidate the aggregation behavior around the cloud point we performed small-angle neutron scattering experiments. The unimer radii increase upon heating towards the cloud point which is consistent with an onset of aggregation. Above the cloud point, we first encounter an intermediate regime, where, instead of the expected collapse, the small aggregates formed below the cloud point, dominate. Large aggregates are only formed a few Kelvin above the cloud point.
[1] S. Salzinger, S. Jaksch, C.M. Papadakis et al., Coll. Polym. Sci. accepted