Wetting regimes at a semipermeable membrane

The different possible wetting regimes occurring at a model semipermeable membrane (which separates a binary system into two fluid mixtures) are analyzed in the space of temperature T, membrane field ${\epsilon }_1$, and the chemical potential of the constrained species ${\mu }_2^{\mathrm{-}}$. We focus attention on the effect that the distance (in thermodynamic space) of the two bulk states has on the nature of the membrane interfacial transitions. The departures encountered from the wetting behavior for fluid-to-wall and fluid-fluid interfaces are emphasized.