Solubilization and release of hydrophobic compounds from block copolymer micelles. I. Partitioning of pyrene between polyelectrolyte micelles and the aqueous phase

Abstract

Partitioning of pyrene between poly(tert-butylacrylate)-block-poly(2-vinylpyridine) and polystyrene-block-poly-(methacrylic acid) micelles and aqueous solvent has been studied by fluorometric techniques. The partition coefficient was evaluated on the basis of the steady-state fluorescence spectra and the time-resolved fluorescence decays from a series of solutions with decreasing copolymer concentrations, and the obtained values were compared. The agreement is very good. In the accompanying paper, the release kinetics of pyrene from micelles upon a sudden and prodigious dilution of micellar solution by the aqueous solvent was studied by time-dependent measurements of the steady-state fluorescence intensity. Simultaneous mathematical treatment of dilution curves in the absence and presence of water-soluble quencher based on the model of diffusion from a sphere allows the diffusion coefficient of pyrene in micellar cores to be evaluated. The assumption that micelles do not reorganize upon the shock dilution is tested by an independent experiment.