Dresden 2026 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster I

CPP 17.50: Poster

Montag, 9. März 2026, 19:00–21:00, P5

Dynamic wetting of mixed rod-sphere suspensions and its relation to the suspension rheology — •Reza Azizmalayeri and Günter Auernhammer — Leibniz-Institut für Polymerforschung Dresden e. V.

In this study, we examine dynamic wetting of mixed rod-sphere suspensions near the advancing contact line. We compare pure spherical suspensions with 98:2 sphere-rod mixtures. Using a pinned droplet and moving substrate geometry on an inverted microscope, we achieve a locally stable contact line. Astigmatism Particle Tracking Velocimetry (APTV) measures the trajectories of tracer particles within the refractive index-matched suspension. Pinch-off experiments conducted via the Dripping-onto-Substrate (DoS) method provide Protorheology insights into shear and extensional viscosities. We analyse rod dynamics and orientation as they approach the advancing contact line, interact with the substrate, and re-enter the bulk suspension. In purely spherical suspensions, tracer trajectories near the advancing contact line deviate significantly from hydrodynamic model predictions. Conversely, mixed rod-sphere suspensions exhibit minimal deviations. Rod inclusion reduces effective viscosity during pinch-off, promoting deformation and thread thinning. This effect is amplified by rod-induced polydispersity and the disruption of spherical contact structures, weakening resistance to flow and altering rheology. Visualizations reveal that rods align parallel to the contact line, then rotate 90 degrees to align with the substrate.

Keywords: Wetting; Rheology; Granular Suspension; Complex Fluid