Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 23: Polymer Dynamics

CPP 23.2: Talk

Wednesday, March 13, 2013, 10:00–10:15, H39

The collapse transition of poly(2-oxazoline) gradient copolymers - a multistep process — Sebastian Jaksch¹, Konstantinos Kyriakos¹, Jianqi Zhang¹, Isabelle Grillo², Anita Schulz³, Rainer Jordan³, and •Christine M. Papadakis¹ — ¹TU München, Physik-Department, Physik weicher Materie, Garching — ²Institut Laue-Langevin, Grenoble — ³TU Dresden, Department Chemie, Professur für Makromolekulare Chemie

Thermoresponsive poly[(iso-propyl-2-oxazoline) (PiPrOx) polymers in aqueous solution exhibit a strong change in solubility and chain conformation when heated above their cloud point (CP). The CP decreases strongly upon insertion of few hydrophobic monomers.

We investigated poly[(iso-propyl-2-oxazoline)-grad-(n-nonyl-2-oxazoline)] (P[iPrOxNOx]_grad) gradient copolymers with a varying fraction of NOX moieties. In temperature-resolved SANS experiments, we have found a two-step collapse and aggregation behavior of the gradient copolymers at the cloud point which is not present in the homopolymer [1]. Time-resolved SANS allowed us to monitor the structural evolution of the aggregates when rapidly heating the solutions from below the CP to different temperatures above. We found that, the higher the target temperature, the more pronounced is the collapse. Moreover, the aggregates present in the intermediate regime are stable and do not transform into those found at higher target temperatures.

[1] S. Salzinger, S. Jaksch, C.M. Papadakis et al., Colloid Polym. Sci. 290, 385 (2012).