Single-particle level access to hydrodynamic and frictional coupling between spheres in dense colloidal suspensions

Abstract

The rotational Brownian motion of colloidal spheres in dense suspensions reflects local hydrodynamics and friction, both key to non-linear rheological phenomena such as shear-thickening and jamming, and transport in crowded environments, including intracellular migration and blood flow. To fully elucidate the role of rotational dynamics experimentally, it is crucial to measure the translational and rotational motion of all spheres simultaneously. Here, we develop compositionally uniform colloidal spheres with an off-centre, fully embedded core with a different fluorophore to the particle body, allowing access to rotational motion for all particles at the single-particle level. We reveal interparticle hydrodynamic rotational coupling in charged colloidal crystals. We also find that higher local crystallinity in denser crystals enhances rotational diffusivity, and that nearly arrested particles exhibit a stick-slip rotational motion due to frictional coupling. Our method sheds new light on the largely-unexplored local rotational dynamics of spherical particles in dense colloidal materials.

Manuscript 9 pages, 4 figures; Supplementary Information 14 pages, 3 figures

References in corpus (5)

• Liquid Crystal Colloids
• Crystallization kinetics of colloidal model suspensions: recent achievements and new perspectives
• Purely hydrodynamic ordering of rotating disks at a finite Reynolds number
• Hydrodynamic coupling of two rotating spheres trapped in harmonic potentials
• A novel particle tracking method with individual particle size measurement and its application to ordering in glassy hard sphere colloids

Cited by in corpus (4)

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• Attraction-enhanced emergence of friction in colloidal matter
• Microrheology with rotational Brownian motion