Colloids confined to a flexible container.

A model of hard spheres trapped inside a container of fluctuating shape is proposed to describe colloidal particles in a vesicle or in an emulsion droplet. The container is assumed to be the convex hull of the particles and is described by an integral geometric approach including volume and surface terms. In the limit of large volume coupling, the model reduces to the well-known geometric problem of natural bin packing. Using computer simulations and cell theory, we calculate equilibrium properties for various finite numbers of confined particles in conformations ranging from clusters to planar and linear structures and identify transitions between these different conformations.