| Abstract
| - Interactions of surfactants with hydrophobically modified polyelectrolytes in aqueous solutions areimportant in several applications such as detergency, cosmetics, food, and paints. Complexes formed inthese systems raise some fundamental questions about the polymer−surfactant interactions that controltheir behavior. In this work, the interactions of a nonionic surfactant, penta-ethyleneglycol mono n-dodecylether (C12EO5), with a hydrophobically modified anionic polymer, poly(maleic acid/octyl vinyl ether)(PMAOVE), in aqueous solutions were studied using surface tension, viscosity, electron paramagneticresonance (EPR) spectroscopy, light scattering, and fluorescence spectroscopic techniques. When the nonionicsurfactant C12EO5 was added to aqueous solutions of the anionic polymer PMAOVE, it was incorporatedinto the hydrophobic nanodomains of PMAOVE far below the the critical micelle concentration (cmc) ofthe surfactant. Two inflection points were observed corresponding to the critical complexation concentration(formation of mixed micelles composed of C12EO5 and the octyl chains of PMAOVE) and the saturationconcentration (saturation of the polymer with C12EO5 molecules). Above the saturation concentration, thecoexistence of pure C12EO5 micelles and mixed micelles of PMAOVE and C12EO5 was observed. Such acoexistence of complexes has major implications in their performance in colloidal processes.
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