The Control of Morphology, Crystalline Forms and Dispersability of Colloidal Particles by Solubilized States of Water in Reversed Micellar Solutions

Abstract

In order to make clarify the influence of solubilized water on the morphology, crystalline forms and dispersability of colloidal particles in reversed micellar systems, the solubilized states of water in ionic and nonionic reversed micellar solutions were examined as a function of Rw (= [H2O] / [surfactant]) by various spectroscopic techniques. As a result, two or three typed water were found to exist in varying proportions in the interior of these reversed micelles, i.e., water bound to the polar groups of surfactants, water bound to the hydrated polar groups, or bulk-like water. The micellar phase diagrams which related with these states of water allowed us to calculate the minimum Rw required for the formation of reversed and swollen micelles or W/O microemulsions, and other parameters. Then the synthesis and dispersability of colloidal particles in these micelles containing each typed water were studied. As a result, the size and morphology of GeO2 particles, prepared by hydrolysis of Ge (OC2H5) 4 in Aerosol OT solutions, and the crystalline forms of CaCO3 particles, prepared by bubbling CO2 into solubilized aq. Ca (OH) 2 solutions in nonionic surfactant solutions were found to be controlled by each state of water in the interior of reversed micelles. The control by the solubilized states of water was also observed for the dispersability of TiO2 particles in Aerosol OT and nonionic reversed micellar systems.