THERMODYNAMICS OF FLUIDS IN RANDOM MICROPOROUS MATERIALS FROM SCALED PARTICLE THEORY

The thermodynamic properties of fluids confined to disordered porous s olids are studied using a scaled particle theory approach. For simple hard sphere fluids in matrices of hard spheres, this method is of comp arable accuracy to those previously introduced. In past studies of suc h systems, a strong thermodynamic similarity between the partly quench ed and fully annealed cases has been evident; an exception to this beh avior occurs when the diameters are nonadditive. For adsorbed polymeri c molecules, on the other hand, the scaled particle theory introduced in this paper is the only route to the thermodynamics yet presented. T he partition coefficients for polymers at infinite dilution in matrice s of various porosities agree well with simulation over many orders of magnitude. For bulk polymers, the scaled polymer predictions are in m uch closer agreement with simulation than those of the traditional pre ssure and compressibility equations. (C) 1995 American Institute of Ph ysics.