Self-Assembly of Monolayers of Mixtures of Particles

We have numerically studied the self-assembly process of particle mixtures on fluid-liquid interfaces when an electric field is applied in the direction normal to the interface. The electric and capillary forces on the particles causes them to self-assemble into molecular-like hierarchical arrangements consisting of composite particles arranged in a pattern. As in experiments, the structure of a composite particle depends on factors such as the relative sizes of the particles and their polarizibilities, and the electric field intensity. If the particles sizes differ by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles forming a ring around it. The number of particles in the ring and the spacing between the composite particles depends on their relative polarizibilities, the size of the smaller particles and the electric field intensity. Approximately same sized particles, on the other hand, form chains (analogous to polymeric molecules) in which positively and negatively polarized particles alternate.