Correlation of data on preferential sorption using the modified flory‐huggins equation

Abstract

AbstractAn equation derived from the Flory‐Huggins relation with the concentration‐dependent interaction parameters gij and the ternary parameter gT was used in the correlation of reported data on the preferential sorption in macromolecular coils. A linear plot was suggested, assuming that the dependence of gT on the composition of the mixed solvent resembles that of g12, i.e. gT(u1) = ag g12(u1). Linear correlation could be carried out in 19 ternary systems out of 22, and the correlation constants were used to calculate the difference of interaction parameters g13 − (V1/V2)g23 and the proportionality constant ag. For most systems, ag is positive and smaller than unity; for systems containing chloroform it approaches zero. The difference between the interaction parameters gij and the interaction parameters χij is discussed. A comparison between the difference g13−(V1/V2)g23 obtained by a linear correlation of data on preferential sorption with the values calculated using data on the respective binary systems was possible only for the system benzene/cyclohexane/polystyrene; the fit was very good. It is shown how the individual parameters of the Flory‐Huggins equation affect the occurrence, position and type of inversion in preferential sorption.