Abstract
A phenomenological model for the unbinding transition of multicomponent fluid membranes is proposed, where the unbinding transition is described using a theory analogous to the Flory-Huggins theory for polymers. The coupling between the lateral phase separation of inclusion molecules and the membrane-substrate potential provides a rich phase behavior. Our model describes the first-order nature of the unbinding transition in multicomponent membranes as was observed in a recent experiment. In particular, we predict different scenarios of phase coexistence between bound and unbound membrane states.