Strongly non-additive symmetric mixtures in slit-like pores

Abstract

Using Monte Carlo simulation methods in the grand canonical ensemble, we have studied the behavior of symmetric binary mixtures confined between attractive planes. We have elucidated the effects of high negative geometric and energetic non-additivity on the phase behavior of mixtures in nanoscopic slit-like pores. In such systems, the geometric non-additivity favors mixing, while the energetic non-additivity favors the formation demixed dense phases. It has been shown that the confinement considerably influences the phase behavior. In particular, phase separation has been found to be suppressed in narrow pores, while in wide pores the phase behavior becomes qualitatively the same as in bulk systems. It has also been demonstrated that the demixed solid is stable over a certain temperature range in pores, while the bulk mixtures characterized by the same non-additivity exhibit only the presence of mixed solid.