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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: French-German Session: Membranes and Porous Materials I

CPP 3.5: Vortrag

Montag, 9. März 2026, 10:45–11:00, ZEU/LICH

Is it possible to use nano-confined water for cloaking or magnifying of static electric fields? — •Kira Fischer¹, Julia Brandt¹, Philipp Stärk², Alexander Petrov¹, and Alexander Schlaich¹ — ¹Hamburg University of Technology — ²University of Stuttgart

Assuming radial anisotropy in the dielectric response of water in cylindrical or spherical confinement, Kettunen et al., have shown that for certain ratios of permittivity contrast it is possible to cloak the interior sample, or to magnify the response of an inner cylinder. Indeed, water at interfaces and in confinement shows a strongly anisotropic dielectric response, with high dielectric permittivity in parallel and low permittivity perpendicular to the interface, as observed experimentally by Fumagalli et al.

Here, we probe the radial and azimuthal dielectric response of water in cylindrical confinement. We do so by calculating the dielectric permittivity profile from molecular dynamics simulations, both using a Green-Kubo relation as well as applied fields. Near the interface, we observe a high dielectric permittivity in the azimuthal direction and a low dielectric permittivity in the radial direction of the cylinder, supporting the concept of radial anisotropy.

Applying a static, homogenous external field we then analyse the resulting water polarization. The observed effective response of water inside a cylinder is almost bulk like, and no significant cloaking effect is observed. We use effective medium theory to rationalize this behavior and discuss possible applications of cloaking in model fluids.

Keywords: dielectric; water; nano-confinement; molecular dynamics