Abstract: The solubilization of naphthalene, anthracene and pyrene, in both F127 and P123 aqueous micellar solutions has been characterized by UVmethod. These aromatic hydrocarbons were confirmed to incorporate in the micellar cores. The model of stepwise association equilibrium was used to analyze the experimental results and the first stepwise association constant K₁ between solubilizate monomer and vacant micelle was thus obtained. It was found that the values of K₁ increased with increasing the benzene cycle number of the aromatic hydrocarbons. The average number of solubilizating molecules corresponding to each PO-group in the mcellar cores was verified to be consistency for both F127 and P123 This result suggests that the volume of the micellar core is an important factor to determine the amount of aromatics incorporating into Pluronic micelles. The amount was lineally enhanced with increasing the volume of the micellar core. The stability in planar ring of the molecule of polycyclic aromatic hydrocarbon also affected its solubilization. It was shown by the solubilization isotherms that anthracene and pyrene have a higher efficiency in solubilization compared with naphthalene.

Key words: Pluronic block copolymer, Micellar solubilization, Polycyclic aromatic hydrocarbons