Interfacial tension solute-cosolvent

Miscible organic solutes modify the solvent properties of the solution to decrease the interfacial tension and give rise to an enhanced solubility of organic chemicals in a phenomenon often called cosolvency . According to theory, a miscible organic chemical such as a short chain alcohol will have the effect of modifying the structure of the water in which it is dissolved. On the macroscopic scale, this will manifest itself as a decrease in the surface tension of the solution [238,246]. 

The use of the ADR method may not always provide accurate vehicle compositions for a given solute since intermolecular forces are dependent on structural characteristics of the solvent and solute that are not expressed by It is possible, and perhaps desirable, to substitute other measures of cosolvent polarity, such as solubility parameter, surface or interfacial tension, etc., for e when blending solvents, although inaccuracies in vehicle predictions will generally continue to exist. 

In Table III the results of adding excess acid to sodium oleate solutions are given. These data are not directly comparable to Figure 5 since the aqueous phase contains cosolvent and the solutions were preequilibrated before testing. However, the trend to lower interfacial tension with increasing additions of oleic acid (and thus lower pH) is parallel to Figure 5 ... 

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