Dynamics of two-phase lipid vesicles: Effects of mechanical properties on morphology evolution

Multicomponent lipid vesicles can exhibit phase separation of coexisting liquid phases with different mechanical properties, leading to the formation of complex phase morphologies and membrane shapes. We examine the phase separation and the corresponding morphological and geometric evolution in two-phase lipid membrane vesicles using a phase-field method. We investigate the effects of the phase fraction as well as the mechanical properties of each phase on the evolution of the system while conserving surface area and composition. We contrast results for a flexible membrane with those obtained for a fixed spherical geometry with no mechanical coupling. We find that the coupling of bending energy with composition results in slower coarsening and that the phase with spontaneous curvature more similar to the average curvature of the vesicle is favored to form bicontinuous morphologies.