Spatial correlations and solvation interaction in a two-component mixture of adhesive fluids

First, the phase behavior and the spatial correlations in the two-component mixture of adhesive fluids denoted by (1) and (2) are studied on the basis of the solution to the Percus–Yevick/Ornstein–Zernike equation. The isotherm slopes for the correlation function between unlike particles exhibit singularities at the interparticle distances which are the multiple of the molecular size of both species (1) and (2) as a consequence of the impulse character of 1-1, 2-2, and 1-2 adhesive potential of interaction. Then, the above system is treated as an adhesive solvent mixture in which the solvent mediated force between the hard solutes (3) mimicking liophobic colloids is studied. The solution of the Percus–Yevick/Ornstein–Zernike equation for a three-component mixture comprising the two-component adhesive solvent system and the hard sphere colloid is applied in the limit of vanishing solute concentration. Due to the layering of the solvent molecules, the solvation force oscillates with the periods equal to the molecular diameters of both solvent components. The force between the macroparticles in the one-component adhesive solvent [A. Jamnik, D. Bratko, and D. Henderson, J. Chem. Phys. 94, 8210 (1991)] tends to vanish at the critical condition of the model fluid. On the contrary, the solvation force in the two-component adhesive system remains finite even at the critical conditions of the solvent mixture at the specified composition.