Spontaneous partitioning of particles into cellar structures in a membrane system

Membranes are often used for material partitioning in biological systems and industry. Here we report a novel physical mechanism of particle partitioning using topological transformation of bilayer membranes. Upon phase separation of a homogeneous sponge phase of a membrane system into a dense sponge and a water phase, we found quite unusual partitioning behavior of particles into the cellar structure of a water phase. The compartments next to one having particles always have no particles, and those next to a compartment having no particles always have particles. We confirm that this partitioning is purely geometrically induced, and thus it may be universal.