Adsorption and Phase Transitions in Slit-like Pores with Differently Adsorbing Walls

Phase behaviour of a fluid in slit-like pores with differently adsorbing walls: application of a density functional approach

“…Our calculations have demonstrated that the phase behaviour of the fluid confined in pores with differently adsorbing walls may be quite different from that observed in pores with identical walls and that even small changes in the adsorbing properties of one wall may lead to qualitative changes in the phase diagram. The results presented here remain in overall qualitative accordance with the results obtained for lattice systems using a Bragg-Williams approximation [14]. Obviously, the question arises whether the observed changes are not an artefact of a mean-field type approach.…”

“…Thus it is interesting to study how the phase diagram of a confined fluid is altered when the adsorbing potential due to one pore wall is systematically weakened from the initial value, common for both walls, to zero. Such studies have been carried out for a lattice gas confined to a slit-like pore with differently adsorbing walls quite recently [14]. We have observed that if the adsorption energy due to one wall becomes weaker and weaker, a single coexistence envelope, which describes capillary condensation in a pore with two identical walls, splits into several, layering-like branches.…”

Phase behavior of a binary symmetric mixture in slitlike pores with opposing walls: Application of density functional approach

“…This effect is quite similar to that observed for single-component fluids [13,14]. The occurrence of the layering is the first qualitative difference in the thermodynamic behavior of the two systems in question.…”

“…Therefore, it is of interest to investigate the pore models in which the adsorbing properties of the walls change from identical to opposing. In our recent papers we have investigated the adsorption of single-component fluids in slitlike pores with differently adsorbing walls [13,14]. Using lattice as well as off-lattice models we have observed that when the adsorption energy due to one wall is gradually weakened, a single coexistence envelope, which describes capillary condensation in a pore with two identical walls, splits into several, layeringlike branches.…”

Phase diagrams for a binary mixture confined in narrow slitlike pores with energetically heterogeneous walls from a lattice mean-field approach

“…The theory we apply was originally formulated by Lane [21]. Similar approaches have been subsequently applied in numerous studies of nonuniform systems [22][23][24][25][26]. Our principal aim is to study the formation of bridge phases and capillary condensation, as well as an interplay between these transitions and demixing inside the pore.…”