Phase interfaces within different vesicle shapes.

Liquid droplets on flat surfaces generally exhibit a contact angle in a range from 0 to [Formula: see text], but the two-phase interface within a vesicle membrane is very fascinating due to the involved force balance along three bending interfaces. Giant lipid vesicles encapsulated with the poly(ethylene glycol)/dextran aqueous two-phase system are established recently, and the phase interfaces within vesicle membrane are very interesting as experimentally observed. The developed theoretical framework by a combination of the Helfrich curvature elastic theory for vesicle membranes and self-consistent field theory for polymers has been extended to explore aqueous two phases within vesicles. The intrinsic contact angle [Formula: see text] that represents the material parameter, is introduced to describe this phase interfaces within vesicles, especially the transitions from complete wetting to partial wetting, from partial wetting to complete dewetting. The dependence of intrinsic contact angles on the parameters, such as the interaction strengths between the polymers [Formula: see text] and between the membrane and polymer [Formula: see text], the volume fraction [Formula: see text], impermeability of the membrane to the enclosed polymers [Formula: see text] and membrane spontaneous curvature c , are thoroughly investigated, as well as these wetting/dewetting transitions are extensively discussed in the present study.