Modulated phases in multicomponent fluid membranes

We investigate the behavior of flexible two-component bilayer and three-com ponent monolayer membranes. The components are assumed to have different sp ontaneous curvatures, and to mutually phase separate in planar membranes. A s a function of temperature, lateral tension and bending rigidity, a rich p hase behavior is obtained. In particular, we find three different types of modulated phases. In symmetric bilayers, the excess component assembles at the boundary between oppositely curved domains; in sufficiently asymmetric bilayers, the excess component is found to preferentially assemble in a sin glelayer, with no tendency for segregation to the domain boundaries. We sho w that the phase behavior of three-component monolayer strongly resembles t he behavior of two-component bilayers. In fact, in a certain, restricted re gion of parameter space, the two models can be shown to be equivalent. [S10 63-651X(99)07210-4].