Characterizing sliding and rolling contacts between single particles

Proceedings of the National Academy of Sciences, Journal Year: 2025, Volume and Issue: 122(10)

Published: March 6, 2025

Contacts between particles in dense, sheared suspensions are believed to underpin much of their rheology. Roughness and adhesion known constrain the relative motion particles, thus globally affect shear response, but an experimental description how they microscopically influence transmission forces displacements within contacts is lacking. Here, we show that innovative colloidal-probe atomic force microscopy technique allows simultaneous measurement normal tangential exchanged tailored surfaces microparticles while tracking sliding rolling, unlocking direct coefficients rolling friction, as well friction. We demonstrate that, presence sufficient traction, spontaneously roll, reducing dissipation promoting longer-lasting contacts. Conversely, when prevented, friction greatly enhanced for rough adhesive surfaces, smooth coated by polymer brushes maintain well-lubricated find surface roughness induces due load-dependent asperity interlocking, leading large off-axis particle rotations. In contrast, smooth, promote along principal axis motion. Our results offer values numerical studies interpretation onset discontinuous thickening based on them, opening up ways tailor rheology via contact engineering.

Language: Английский

Rolling and ordering of micro rods in shear flow induced by rod wall interactions

Soft Matter, Journal Year: 2024, Volume and Issue: unknown

Published: Jan. 1, 2024

We use experiments and theoretical models to investigate the rolling translational motion of rod-shaped micro particles close a solid wall in presence or absence shear flow.

Language: Английский