SOLVATION FORCE FOR AN ASSOCIATIVE FLUID IN A SLIT-LIKE PORE

The solvation force for an associating fluid inside a slit-like pore i s studied by using a singlet theory of inhomogeneous fluids. A one-com ponent system of hard spheres with an embedded sticky attractive site located inside their hard cores is chosen as a model of the bulk fluid , The bulk fluid is considered in the framework of Wertheim's theory o f association, Two models permitting dimerization and characterized by different bond lengths are investigated, It is shown that the associa tive Percus-Yevick approximation in conjunction with the singlet theor y of inhomogeneous fluids provide a quilitatively correct description of the solvation force dependence on the pore width for low and interm ediate densities, For a fluid of short dimers the applicability of the theory is restricted to low densities. An increase of the degree of d imerization leads to an overall decrease of the value of the solvation force, Its dependence on the pore width is qualitatively similar for low and high degrees of dimerization, For high degrees of dimerization the curves possess cusps for the pore width equal to the bonding leng th, For an increasing density the oscillations of the solvation force are observed, Their decay with an increasing pore width depend on the degree of association, However, in a whole range of the degree of asso ciation, the distance between the first maxima is approximately equal to the hard-sphere diameter. (C) 1996 Academic Press, Inc.