Regensburg 2025 – scientific programme

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PRV: Preisträgervorträge

PRV III

PRV III: Prize Talk

Wednesday, March 19, 2025, 13:15–13:45, H2

Complex liquids under confinement — •Regine von Klitzing^1,2, Michael Ludwig¹, Thomas Tilger¹, and Larissa Braun¹ — ¹Institute for Condensed Matter Physics, Hochschulstrasse 8, 64289 TU Darmstadt — ²Laureate of the Gentner-Kastler-Prize 2025

Complex liquids are widely used in many applications, from industrial painting processes to personal care products. Despite their numerous applications, they are still actively discussed in basic research, e.g. their structural behaviour under confinement. In the present study, colloidal dispersions (e.g. nanoparticle suspensions, micellar solutions) are confined between two surfaces in a Colloidal Probe Atomic Force Microscope (CP-AFM) or in a Thin Film Pressure Balance (TFPB). When approaching the surface, the depletion of the dispersion from the thin film leads to oscillations of the interaction force between the confining surfaces. The structure of the confined colloidal dispersions is compared with their bulk structure, which is analysed by small-angle neutron or X-ray scattering (SANS, SAXS). The results show that the softness and the charge of the particles have a strong influence on the scaling law for the particle distance and the correlation length of the particle distribution, which is not yet fully understood. Another open question is when a charged object can be considered as an ion contributing to the electrostatic screening between two confining surfaces and when it behaves like a charged particle, where the jellium approach could provide a suitable model to describe the experimental data.

Keywords: complex liquids; confinement; nanoparticle suspension; micellar solution; ion-specific effects