STICKY SPHERES IN ADHESIVE PORES

The structure of Baxter's adhesive fluid [R. J. Baxter, J. Chem. Phys. 49, 2770 (1968)] in planar pores with adsorbing walls maintaining the equilibrium with the bulk fluid is considered. The wall-fluid correlations are studied on the basis of the solution to the Percus-Yevick/Ornstein-Zernike equation, obtained by using the analytic results for the direct correlation function of the bulk fluid. In the case of strongly adsorbing walls, the density profiles of hard sphere fluid resemble those in the pore with nonadsorbing walls but with the width decreased by the thickness of the adsorbed monolayers. The profiles of strongly adhesive fluid show maxima at the distances from the wall-fluid contact plane which correspond to the most probable configurations of strongly adhered successive molecular layers. A characteristic feature observed in all cases is the discontinuity in the slope of the profile at the distance one molecular diameter below the wall-fluid contact plane as the consequence of the exclusion volume of adsorbed monolayer. The distribution of the fluid between the bulk phase and the interior of the pore is oppositely affected by the strength of the wall-fluid and the fluid-fluid adhesion. Its dependence on the degree of confinement is more pronounced in narrow pores than at bigger separation between the walls. © 1995 American Institute of Physics.