Dimensional confinement and superdiffusive rotational motion of uniaxial colloids in the presence of cylindrical obstacles.

This article investigates the diffusion, structural, and kinetic behavior of anisotropic spheroidal particles confined within a periodic array of cylindrical obstacles, focusing on how obstacle density and particle shape anisotropy influence nematic alignment and diffusivity. Analytical and Brownian-cluster-dynamics simulations reveal that oblate spheroids tend to align perpendicular, while prolate spheroids align parallel to the cylindrical axis, with the nematic–isotropic phase boundary remaining unchanged by obstacles. Translational diffusivity decreases sharply as confinement increases, exhibiting one-dimensional diffusion along the cylinder axis under extreme crowding, while rotational diffusivity of oblate particles near obstacles shows anomalous flipping and super-diffusive behavior despite global nematic order. These findings highlight the role of obstacle-induced surface interactions in controlling nematic director orientation and particle dynamics, offering insights for designing colloidal systems with tunable structural and transport properties.