Swelling equilibrium in the system ethyl‐benzene‐1,3 diphenylbutane‐crosslinked polystyrene

Abstract
The equations for total and preferential sorptions in a ternary mixture liquid(1)‐liquid(2)‐polymer network(3) were derived for systems obeying the Flory‐Huggins equation with the concentration dependent interaction parameters. The equilibrium degree of swelling of the three styrene‐divinylbenzene copolymers in toluene, ethylbenzene, 2,2′‐ditolyl, 3,3′‐ditolyl, and 1,3‐diphenylbutane was measured along with the total swelling and the preferential sorption in the system of the three members of one homologous series ethylbenzene‐1,3‐diphenylbutane‐crosslinked polystyrene. The difference in molar volumes of components is revealed in two ways: via the combinatorial entropy and the interaction parameters (through the Prigogine‐Patterson structural effect). Both these counteractive influences are more fully compensated in the case of the total swelling than in the preferential sorption. The positive value of χ12 parameter increases the degree of swelling of the polymer in a binary mixture of components 1 and 2, but the increase is lower than that according to the Flory‐Huggins theory; this fact justifies the introduction of a ternary parameter χT as an empirical correction. Similar results were obtained by Bristow in a study of benzene‐cyclohexane‐polymer network systems.