Double phase separation in a confined, symmetric binary mixture: Interface quench effect unique to bicontinuous phase separation

It is found that for a geometrically confined, symmetric binary mixture the secondary phase separation is spontaneously induced by the extremely quick reduction of the interface area caused by the hydrodynamics unique to bicontinuous phase separation. This hydrodynamic coarsening is likely too quick for the concentration diffusion to establish the local equilibrium. This phenomenon is generally observed for nearly symmetric binary mixtures confined both in one-dimensional and in two-dimensional capillaries, under deep quench conditions. This interface quench effect and the resulting double phase separation could exist even for bicontinuous phase separation in bulk.