PARTITIONING OF PYRENE BETWEEN CREW CUT BLOCK-COPOLYMER MICELLES AND H2O DMF SOLVENT MIXTURES/

The effect of solvent composition on the partition coefficient (K-v) o f pyrene between the crew cut micelles formed from highly asymmetric b lock copolymers of polystyrene (500)-b-polyacrylic acid (60) and an H2 O/DMF solvent mixture was studied using a fluorescence method. The tot al number of pyrene molecules incorporated per micelle was also determ ined as a function of polymer concentration and solvent composition. T he relationship between the partition coefficient (K-v) and the mass e quilibrium constant (K) was obtained, and the free energy of transfer of pyrene from the solvent mixture to the micelle was calculated in te rms of K. The results suggest that a gradual change in the solvent com position, which makes it increasingly incompatible with the solubiliza te, may be a good method of loading hydrophobic materials into micelle s.