preferential sorption

in polymers
Synonym: selective sorption
An equilibrium phenomenon, operative in polymer solutions in multicomponent solvents and in polymer networks swollen by multicomponent solvents, that produces differences in solvent composition in the polymer-containing region and in the pure solvent which is in thermodynamic equilibrium with that region. Synonymous with selective sorption.
Purple Book, 1st ed., p. 59 (