Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Charged Soft Matter, Polyelectrolytes and Ionic Liquids II

CPP 50.6: Vortrag

Mittwoch, 14. März 2018, 16:15–16:30, C 243

Effects of counterions on conformation and counterion condensation on polyelectrolytes — •Ulrich Scheler — Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str 6, 01069 Dresden, Germany

Counterion condensation reduces the effective charge in polyelectrolytes. This in turn affects the conformation of the polyelectrolytes, because the repelling force between repeat units is reduced. The hydrodynamic size of the polyelectrolytes in solution is determined from the selfdiffusion coefficient measured by PFG NMR. In combination with electrophoresis NMR the effective charge is determined and compared with the nominal charge from the number of repeat units. Poly(styrenesulfonate) has been titrated with various hydroxides to generate the respective salts. There are the expected differences between mono and bivalent counterions, with the latter resulting in an effective charge reduced by about a factor of two and a hydrodynamic radius reduced by 30%. However the effective charge of the acid with H+ as counterion is 10% larger than for others monovalent counterions. Significant differences in the hydrodynamic radius are observed, which are not simply explained by the counterion condensation. Ion-specific effects are observed as well.