The effects of the solvating power of pure diluents on the porous structure and swelling properties of styrene-divinylbenzene (Sty-DVB) copolymers were investigated. The Hildebrand solubility parameter (delta) and the three-dimensional solubility parameter (deltaT) were used to predict the diluent-polymer affinity. In a general way, deltaT was a better predictor than delta. It was found that the accessibility of polymer surfaces depends not only on the fixed pore volume but also on the elasticity of internuclear chains.