EFFECT OF SURFACTANT CONCENTRATION ON DISPERSION STABILITY AS PROBED BY THE FILM THICKNESS STABILITY MECHANISM

From a practical point of view, we have identified the formation of mi crostructure inside a film leading to film stabilization and a new mec hanism for the stepwise thinning of the film. The life time of foam wi th stratifying films has been observed to be much longer, especially i f the size of the film is less than a critical size. Also, depending o n the effective micellar concentration, monodispersity, film thickness , and area, a two-dimensional in-layer ''hexagonal'' structure (i.e. c olloid crystal-like structure) was observed inside the film, which pro vides the film stability and improves dispersion stability. In additio n, the localization of a lamellar liquid crystal at the interface betw een a gas phase and inverse micellar solution of a hydrocarbon has bee n explained by taking into account the relative contributions from met hyl and methylene groups to the surface tension.