Regensburg 2016 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Ionic Liquids and Water

CPP 33.10: Talk

Wednesday, March 9, 2016, 12:15–12:30, H40

The dielectric response of aqueous water slabs in nanoconfinement — •Alexander Schlaich, Philip Loche, Senta Volkenandt, and Roland R. Netz — Fachbereich Physik, Freie Universiät Berlin, 14195 Berlin, Germany

The dielectric constant of water in nanoconfinement is crucial for the emerging field of nanofluidics and nanochemistry, but also for modeling the electrostatic interaction between extended surfaces such as biological membranes. Furthermore the dielectric permittivity governs transport processes in protein crystals, nanotubes or clays.

The dielectric response at interfaces shows rich features that have profound influence on zeta potentials and capacitance. Using atomistic simulations at prescribed water chemical potential, we present spatially resolved dielectric profiles of water confined between hydrophilic surfaces and show that the water orientation becomes correlated in planar confinement, resulting in a drastic change of the local dielectric response tensor.

Simple modeling confirms that water orientation at the surface influences the response to an external field. The anisotropic dielectric response tensor leads to a modified prefactor of the Coulomb interaction for water in sub-nanometer confinement.