Preferential adsorption coefficient variation

Fig. 1.14 Variation of the preferential adsorption coefficient X with the solvent composition for 2,4-DMP,...

The variation of the preferential adsorption coefficient X with the solvent composition for three mixtures is shown in Fig. 1.16. As in the above cases aromatic components are preferentially adsorbed at low compositions, but, p-xylene is more adsorbed than ethylbenzene or toluene. 

Fig. 1.19 Variation of preferential adsorption coefficient, X, as function of methanol volume fraction tiB0> for PDMI (o), PDEI (A), PDPI ( ), and PDBI ( ), at 298 K. (From ref. [122])...

The interesting phenomenon where a mixture of two poor solvents or nonsolvents for a polymer provides a medium that acts as a good solvent for die polymers has been the objective of many studies, by light scattering, " viscometry, " sorption equilibrium, and fluorescence. From these techniques, it has been possible to appreciate how the second virial coefficient Aj and the intrinsic viscosity [11] preferential adsorption coefficient A, and excimer and monomer emission ratio Ie/Im are involved by changing solvent composition. They present ([T)], A2) a maximum or a variation at a certain solvent composition where the polymer behaves as through it were dissolved in a good solvent. 

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