Regensburg 2019 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Poster Session II

CPP 25.47: Poster

Tuesday, April 2, 2019, 14:00–16:00, Poster B1

Water dynamics in a concentrated poly(N-isopropylacrylamide) solution at high pressure — •Bart-Jan Niebuur¹, Wiebke Lohstroh², Marie-Sousai Appavou³, Alfons Schulte⁴, and Christine M. Papadakis¹ — ¹TU München, Physik Department, Garching, Germany Physik weicher Materie, — ²Heinz Maier-Leibnitz Zentrum (MLZ), TU München, Garching, Germany — ³FZ Jülich, JCNS at MLZ, Garching, Germany — ⁴University of Central Florida, Department of Physics and College of Optics and Photonics, Orlando, U.S.A.

Hydration water is of fundamental importance for the phase transitions of macromolecules in aqueous solution. A complete picture of the dynamics of hydration water is therefore key for identifying the processes involved. Using quasi-elastic neutron scattering, we study the hydration behavior of a concentrated solution of the thermoresponsive polymer poly(N-isopropylacrylamide) during heating through its cloud point (CP). Varying pressure alters its hydration state [1]. At low pressure, the fraction of hydration water decreases sharply at the CP. The diffusion of the remaining fraction gets increasingly hindered, which points to a rearrangement of the hydration water. In the one-phase state at high pressure, the hydration water diffuses more rapidly than at low pressure, which indicates enhanced hydrophobic hydration. At the CP, the fraction of hydration water decreases by a similar amount as at low pressure, but the transition spans over ∼10 K. At high pressure, the hydrophobic groups stay hydrated in the two-phase state. [1] B.-J. Niebuur, C. M. Papadakis et al., ACS Macro Lett. 2017, 6, 1180