Size Effect in the Phase Separation in Three-Component Solutions

A thermodynamic model of the three-component solution with phase separation is proposed. Results from modeling are presented for several ternary systems with core-shell structure. The model is based on a numerical analysis of the Gibbs function that considers the surface energy of the external and internal interphase boundaries. Ternary mixtures with phase separation corresponding to the equations of state of regular, Flory–Huggins, and NRTL solutions are considered as examples. Modeling describes thermodynamically stable and metastable states that are missing from macrosystems. It is shown that the volume and composition of a heterogeneous mixture affects the region of heterogeneity, the equilibrium composition of coexisting phases, and the number of metastable states. A region of the bi-stability of phase equilibria is revealed in which there is competition between different core–shell structures.