Berlin 2015 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: Colloids and Complex Liquids II (joint session CPP, BP, DY)
CPP 8.5: Talk
Monday, March 16, 2015, 16:00–16:15, C 130
Molecular versus macroscopic perspective on the phase separation mechanisms of thermo-responsive solutions — •Martine Philipp1, Ralitsa Aleksandrova2, Ulrich Müller2, Jan K. Krüger2, and Peter Müller-Buschbaum1 — 1TU München, Physik-Department, LS Funktionelle Materialien, Garching, Germany — 2Université du Luxembourg, LPM, Luxembourg, Luxembourg
The phase separation of thermo-responsive solutions is known to strongly affect the volume expansion behaviour and the elastic properties, being directly coupled to the macroscopic order parameter [1-3]. On the molecular scale, massive changes in H-bond and hydrophobic interactions, and in structure govern the demixing process. However, the relationship between the molecular and macroscopic order parameters is poorly understood for such complex segregating solutions. We contribute to the clarification of this problem by first following the diffusion behaviour of the hydration water across the phase transition of model aqueous poly(N-isopropylacrylamide) solutions using quasi-elastic neutron scattering [2]. By probing the molecular bond polarisabilities, we adopt an alternative, highly revealing perspective on the changes in molecular interactions and in structure happening within dilute to concentrated phase-separating solutions [1, 3]. [1] M. Philipp, et al., Soft Matter 10, 7297-7305 (2014), [2] M. Philipp, et al., J. Phys. Chem. B 118, 4253-4260 (2014), [3] R. Aleksandrova, et al., Langmuir 30, 11792-11801 (2014)