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Center for Nonlinear Studies |
Geometric frustration occurs when a system's preferred ordering (e.g. spheres in 2D packing in a hexagonal lattice) is incompatible with the system's geometry (e.g. confinement on a curved surface). An example of this occurs in arrested relaxation in Pickering emulsions, where a droplet in an emulsion is held in a non-spherical shape due to a close-packed coating of particles adsorbed on the droplet interface. These structures tend to be relatively well ordered with regions of highly hexagonal packings; however, the curvature of the surface prevents perfect ordering and defects in the packing are required. These defects may influence the stability of these structures, making it important to understand how to predict and control them for applications in the food, cosmetic, oil, and medical industries. In the work presented here, we use simulations to study the ordering and stability of sphere packings on arrested emulsions droplets. We begin by isolating the role of surface geometry by creating packings on a static ellipsoidal surface. Next we investigate dynamic effects that occur during droplet formation, including surface relaxation rate, interparticle attraction, and gravity. Finally, we study jamming on curved surfaces, focusing on the role geometry plays in constraining the packing as well as how it influences mechanical properties.