Factors to Increase the Mutual Solubility of Oil and Water by Solubilizer

Abstract

It was confirmed from the studies of phase diagrams that the Schulman's so-called microemulsion is not an emulsion, but a solubilized solution. It is desirable to find conditions to produce so-called microemulsions in which the solution is stable and solubilization is large that oil and water mix to each other over wide composition range. Following conditions were found in order to increase the mutual solubility of oil and water with far less amount of solubilizer.(1) Optimum Hydrophile-Lipophile Balance (HLB) or Phase Inversion Temperature (PIT) of a surfactant.(2) Optimum mixing ratio of surfactants (solubilizer), i. e., optimum HLB (or PIT) of the mixture.(3) Optimum temperature for a given nonionic solubilizer.(4) The closer the HLBs of two surfactants, the larger the solubilization.(5) If the HLBs of two surfactants are close, mixtures of ionic and nonionic surfactants is better.(6) The larger the molecular size of solubilizer, the more efficient the solubilization.