Phase behaviour of symmetric binary mixtures with partially miscible componentsin slit-like pores. Application of the fundamental measure density functionalapproach

Abstract

We investigate adsorption in slit-like pores of model symmetric binary mixturesexhibiting demixing in bulk phase, by using a density functional approach. Ourfocus is on the evaluation of the first-order phase transitions in adsorbed fluidsand the lines separating mixed and demixed phases. The scenario for phasetransitions is sensitive to the pore width and to the energy of adsorption.Both these parameters can change the phase diagrams of the confinedfluid. In particular, for relatively wide pores and for strong wall–fluidinteractions, the demixing line can precede the first-order transition. Moreover, acompetition between layering transitions and demixing within particularlayers also leads to further enrichment of the phase diagram.