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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 50: Charged Soft Matter, Polyelectrolytes and Ionic Liquids II
CPP 50.5: Talk
Wednesday, March 14, 2018, 16:00–16:15, C 243
Counterions in aqueous planar nano-confinement: Atomistic simulations and continuum modeling — •Alexander Schlaich1,2 and Roland R. Netz1 — 1Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Laboratoire Interdisciplinaire de Physique (LIPhy), CNRS and Université Grenoble Alpes, F-38000 Grenoble, France
Continuum models for the electrostatic interaction between charged surfaces have been employed successfully to model the interaction between charged surfactants and lipid membranes, yet in nano-confinement additional effects such as the hydration force and dielectric effects need to be taken into account. Here, we perform water-explicit atomistic simulations of monovalent counter-ions confined between planar, charged decanol surfaces at prescribed water chemical potential, allowing to access the interaction pressures and charge distributions in sub-nanometer confinement. At low surface charge density we find additive contributions to the repulsion due to the exponential hydration interaction and counterion entropic effects. The modified Poisson-Boltzmann equation, including the dielectric profile, the fluctuating external charge distribution of the surface and ion-surface interactions, quantitatively describes the ion distribution from several nanometer separations down to strongest confinement, corresponding to kilobar interaction pressures.