Dresden 2026 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 23: Complex Fluids and Soft Matter (joint session DY/CPP)
DY 23.9: Vortrag
Dienstag, 10. März 2026, 11:45–12:00, ZEU/0160
Near-surface colloidal dynamics in jammed and slipping microgel suspensions — •Masoodah Gunny1, Frédérick Caetano2, Matilde Bureau2, Alexandre Vilquin1, Marie Le Merrer2, Catherine Barentin2, and Joshua McGraw1 — 1Gulliver - CNRS, ESPCI-PSL 10 Rue Vauquelin 75005 Paris, France — 2ILM - CNRS, Claude Bernard University, 16 Enrico Fermi 69100 Villeurbanne, France
Jammed suspensions of soft microgel particles exhibit wall slip along smooth boundaries. The direct observation of dynamics within a supposed depletion layer near the wall were difficult to achieve as a result of the layers' supposed sub-micrometric dimensions. We use total internal reflection fluorescence microscopy (TIRFM) to observe colloidal-particle dynamics near the interface between glass and microgel suspensions. Remarkably, microgel suspensions display nanoscale velocity profiles with a slope rupture; particle velocity increases with distance near the wall, and tends to a constant beyond a distance which is characteristic of the ones predicted previously. Beyond velocimetry, we also study the statistical particle altitude distributions near the wall in TIRFM measurements. These distributions are strongly pressure dependent, with nanoparticles more likely found near the solid/liquid interface when the fluid is transported faster near the wall. This high-velocity particle enrichment, not seen for the Newtonian case, is consistent with the development of a depletion layer under such conditions. Taken together, our observations give strong support for the existence of a depletion layer being responsible for wall slip.
Keywords: microgel slip; near-surface dynamics; jammed suspensions
