The role of curvature anisotropy in the ordering of spheres on an ellipsoid

TL;DR

This study uses large-scale simulations and experiments to explore how curvature anisotropy influences the arrangement and defect formation of particles on ellipsoidal surfaces, revealing complex defect patterns and packing behaviors.

Contribution

It provides new insights into the relationship between surface curvature anisotropy and particle packing, including defect distribution and scar formation, on ellipsoidal surfaces.

Findings

Defects are most common in regions of strong curvature.

Secondary maxima in defect distribution occur at high aspect ratios.

Experimental verification of colloid-stabilized ellipsoidal droplets.

Abstract

Non-spherical emulsion droplets can be stabilized by densely packed colloidal particles adsorbed at their surface. In order to understand the microstructure of these surface packings, the ordering of hard spheres on ellipsoidal surfaces is determined through large scale computer simulations. Defects in the packing are shown generically to occur most often in regions of strong curvature; however, the relationship between defects and curvature is nontrivial, and the distribution of defects shows secondary maxima for ellipsoids of sufficiently high aspect ratio. As with packings on spherical surfaces, additional defects beyond those required by topology are observed as chains or 'scars'. The transition point, however, is found to be softened by the anisotropic curvature which also partially orients the scars. A rich library of symmetric commensurate packings are identified for low particle number. We verify experimentally that ellipsoidal droplets of varying aspect ratio can be arrested by surface-adsorbed colloids.