ABSTRACT
It has been shown previously that the phase behavior of water-oil and amphiphile mixtures can be satisfactorily depicted by the R-theory. This theory, originally developed by Winsor, is based on the qualitative consideration of the interactions of the surfactant relatively to oil and water. Firstly, we show experimental evidence of the power of the R-theory as a tool for optimizing microemulsion formulations. Then, we give a thermodynamical justification of the concepts underlying the R-theory. Lastly, it is shown that, with a very limited number of adjustable parameters, it is possible to calculate series of phase diagrams obtained with ethoxylated alkylphenols, n-alkanes and water.