Compared solubilisation properties of bulk micelles and confined surfactant phases

The partitioning of four organic compounds, phenol, 3-chlorophenol, 3,5-dichlorophenol and paratoluidine, between water and either bulk cationic surfactant micelles and surfactant aggregates confined in porous silica is studied. The partition coefficients between the two types of surfactant phase and water are determined from both theoretical models and experiments and compared to that between octanol and water. In many points the behaviour of the confined phase parallels that of bulk micelles: energetics of transfer, evolution of solute partition coefficient with hydrophobic character, evolution of confined surfactant aggregate stability with solute concentration.