Nonionic surfactant systems above the PIT Part II. Molecular aggregate structures

Abstract

For systems just above the PIT, attempts of correlation between phase behaviour in some ternary oil/nonionic surfactant/water systems and molecular structures are presented. The structural investigations have been performed mainly by small angle neutron scattering, making use of the contrast variation method. Emphasis is put on the morphology of the interfacial surfactant film: thickness of the hydrophobic and hydrophilic parts, oil and water penetration into the film, area per polar head, mean curvature. Results in various oil/surfactant systems show that apolar micellization and water solubilization are not markedly correlated. A whole picture of the evolution of the inverse structures is more specifically reported for decane/C₁₂EO₄ concerned especially with the influence of temperature.