Regensburg 2022 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Charged Soft Matter, Polyelectrolytes and Ionic Liquid
CPP 13.3: Vortrag
Dienstag, 6. September 2022, 10:15–10:30, H38
Temperature Dependence of PSS diffusion in multilayers of entangled PDADMA: more than one diffusion constant — •Annekatrin Sill1, Peter Nestler2, Peter Thran1, and Christiane A. Helm1 — 1University of Greifswald, Institute of Physics, D-17489 Greifswald, Germany — 2ZIK HIKE-Biomechanics, University of Greifswald, D-17489 Greifswald, Germany
Layer-by-layer assembly is a widely used tool for engineering materials and coatings, but the dynamics of the constituent polymer chains remain poorly understood. Using neutron reflectivity, the vertical diffusion of polyanion PSS (Mw(PSS) = 75.6 kDa) within PSS/PDADMA (Mw(PDADMA) = 72.1 kDa) multilayers is probed while annealing in 1 M NaCl solution at different temperatures. The observed diffusion could not be described by a simple diffusion model. Instead, two different PSS fractions (one mobile and one almost immobile, i.e. different diffusion constants) are the simplest model to describe the time dependence of the scattering length density profiles. Increasing the annealing temperatures (20 - 50 °C) increases the diffusion constant of both the fast and slow PSS fraction. Additionally, the fraction of fast PSS molecules is increased. We suggest that an immobile or nearly immobile fraction of polyelectrolytes is always present when the polymer length is beyond the entanglement limit and the sticky reptation model fails.