PHASE-SEPARATION AND CURVATURE OF BILAYER-MEMBRANES

Phase separation of two-component mixtures in fluid bilayers is shown to result in a stable one-phase vesicle region near the critical composition for the mixture. The resulting phase diagram exhibits tricritical behavior: The critical point for phase separation lies on the line of continuous transitions between lamellar and vesicle phases. Near the continuous transitions, the polydispersity of the resulting vesicles is large. Possible implications for experiments on two-component surfactant systems are also discussed.