(684a) Assembly of Multiple Anisotropic Particles by Capillary Interactions

Anisotropic colloidal particles at interfaces self-assemble via capillary interactions. We have been exploring the role of particle shape in determining the interfacial deformation and hence the resulting capillary interactions. Here we study multi-particle systems of elongated particles. On crowded surfaces, capillary interactions drive the formation of structures with both positional and orientational order. The formation of these structures strongly depends on the interface distortion created by each particle, which is characterized by elliptical quadrupolar deformation fields for elongated particles. In this work, we simulate relatively large ensembles of particles modeled as interacting elliptical quadrupoles with near-field interactions ranging from repulsive to ?sticky'. Particles are added sequentially to the interface with random positions and orientations. The forces, torques, particle trajectories, and structures upon aggregation are simulated and compared to experimental results obtained for cylindrical micro-particles. The simulations highlight the importance of accounting for the detailed particle geometry, which determine the near field interactions, when dealing with capillary interactions.