PREFERENTIAL ADSORPTION IN POLYMER SOLVENT-1 SOLVENT-2 SOLUTIONS BY INFRARED-SPECTROSCOPY

IR spectroscopy is shown to be a suitable technique for preferential adsorption studies in the following solvent-1/solvent-2/polymer systems: poly(N-vinylcarbazole) and polyacenaphthene in nitrobenzene, dioxane, nitrobenzene/tetrahydrofuran, and nitrobenzene/cyclohexanone. Values of the preferential adsorption parameters derived from the Schultz-Flory theory agree with those from IR when both solvents in the ternary system are considered to be good solvents for the polymer. In the systems studied, the relative adsorptions of solvent-1 and solvent-2 by the polymer depend on the solvent mixture composition. The number of adsorbed molecules and their performance are correlated with the ternary interaction parameters, Xm,3, and the Mark-Houwink-Sakurada exponent, a′. The adsorption changes observed are greater in those systems in which tetrahydrofuran was present.