Adsorption and phase transitions in a two-site associating Lennard-Jones fluid confined to energetically heterogeneous slit-like pores; application of the density functional method

A density functional approach is used to study adsorption and phase behavio ur of the two-bonding-site associating Lennard-Jones (LJ) fluid in slit-lik e pores with energetically heterogeneous walls. Phase behaviour of strongly and weakly associating, polymerizing fluid in the pores with a periodic su rface potential, characterized by different strengths and the spacings betw een adjacent minima, as well as different pore widths is discussed. A compa rison of the results obtained for strongly and weakly associating fluids el ucidates the role of bonding between fluid species in the pore-filling mech anism. An interplay between layering transitions, the formation of an inter mediate 'bridge' phase and the final capillary condensation in the pores wi th energetically corrugated walls is discussed in detail.