Micellar size changing in the systems of octaethylene glycol mono(n-dodecyl) ether without and with poly(acrylic acid)

Abstract Aqueous octaethylene glycol mono(n-dodecyl) ether (C 12 E 8 ) solutions, in the absence and presence of poly(acrylic acid) (PAA) are studied by means of viscosity, pH, refractive index, static fluorescence and dynamic light scattering measurements. At high surfactant concentrations, these properties present inflection points. They are different by the classical critical points (critical micelle concentration and critical interaction concentrations) of such systems and appear at almost the same surfactant concentration, irrespective of the polymer presence. The results are interpreted in terms of micellar size and shape changes. Some images collected with two microscopes prove these changes and the coexistence of various shaped aggregates.