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arXiv · 2609.03540

Near-surface colloidal dynamics in jammed and slipping microgel suspensions

Masoodah Gunny·Frédérick Caetano·Matilde Bureau·Alexandre Vilquin·Marie Le Merrer·Joshua D Mcgraw·Catherine Barentin
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Abstract

Jammed suspensions of soft microgel particles may exhibit slippage along smooth boundaries. Owing to their expected sub-micrometric dimensions, direct observations of dynamics within the near-surface layers supposed to be responsible for this slippage have been difficult to achieve. Here, we use total internal reflection fluorescence microscopy (TIRFM) to observe nanoparticle dynamics near glass/microgel-suspension interfaces. Indicating near-wall dynamic heterogeneity, velocity profiles for suspensions are nonlinear. These profiles tend to a constant slippage velocity at submicrometric distances from the wall, consistent with macroscopic wall slip measurements. Furthermore, nanoscale particle altitude distributions are strongly dependent on the slip velocity, revealing a dynamically-mediated and nanoscale particle-organisation effect. The collected observations give support for the existence of near-wall heterogeneity as a dominant mechanism contributing to microgel wall slip. Our work also opens new perspectives for the study of particle dynamics and organisation in complex interfacial environments.

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Masoodah Gunny, Frédérick Caetano, Matilde Bureau, Alexandre Vilquin, Marie Le Merrer, Joshua D Mcgraw, Catherine Barentin. 2026-09-03. Near-surface colloidal dynamics in jammed and slipping microgel suspensions. https://arxiv.org/abs/2609.03540

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