Rheology and 3D rotational dynamics of sheared dense colloidal suspensions

In this talk, we will discuss the synthesis of novel colloidal particles and our recent results on the rotational dynamics of dense colloidal suspensions that are subjected to externally applied shear. Our in-house synthesized colloidal OCULI particles [1] have an offset core-shell construction, providing a real-space quantification of the rotational dynamics of each individual particle. Using our custom confocal-rheology platform, we quantify the flowing state of these materials to observe the collective rotational behavior. This system allows us to simultaneously perform high-resolution 3-D imaging in time while performing bulk rheology. We track the particles within the dense colloidal dispersion when subjected to shear flow to link shear transformations to collective rotations within localized yielding events. Furthermore, we vary the surface roughness of OCULI particles to explore the effect of rotational constraints on bulk rheology.

(1) Yanagishima, T.; Liu, Y.; Tanaka, H.; Dullens, R. P. A. Particle-Level Visualization of Hydrodynamic and Frictional Couplings in Dense Suspensions of Spherical Colloids. Phys. Rev. X 2021, 11 (2), 021056. https://doi.org/10.1103/PhysRevX.11.021056.