ADSORPTION OF A HARD-SPHERE FLUID IN A DISORDERED POLYMERIZED MATRIX - APPLICATION OF THE REPLICA ORNSTEIN-ZERNIKE EQUATIONS

A model of hard spheres adsorbed in disordered porous media is studied using the associative replica Ornstein-Zernike (ROZ) equations. Exten ding previous studies of adsorption in a hard sphere matrices, we inve stigate a polymerized matrix. We consider an associating fluid of hard spheres with two intracore attractive sites per particle; consequentl y chains consisting of overlapping hard spheres can be formed due to t he chemical association. This is the generalization of the model with sites on the surface of Wertheim that has been studied in the bulk by Chang and Sandler. The matrix structure is obtained in the polymer Per cus-Yevick approximation. We solve the ROZ equations in the associativ e hypernetted chain approximation. The pair distribution functions, th e fluid compressibility, the equation of state and chemical potential of the adsorbed fluid are obtained and discussed. It is shown that the adsorption of a hard sphere fluid in a matrix at given density, but c onsisting of longer chains of overlapping hard spheres, is higher than the adsorption of this fluid in a hard sphere matrix. (C) 1997 Academ ic Press.