Because the apparent and partial molar volumes of ethanol and water practically do not depend on the composition and concentration of the TX-100 and CTAB mixture, the interactions between the water and ethanol molecules affect only these volumes.
Taking into account ¯VMof ethanol and water at a given X2, the sum of these volumes was calculated (Fig. S5). It appeared that the shape of the changes of this magnitude as a function of X2 in the bulk phase is similar to that in the solution of “pure” alcohol and there is the maximum corresponding to X2= 0.5 on these curves. This maximum indicates that there is a minimal deviation between the volume of the real and ideal solutions if the ratio of alcohol molecules to water is 1:1. It is interesting that the changes of the sum of partial molar volumes of water and alcohol as a function of the solution composition are some what similar to those of the excess free enthalpy of water and alcohol mixing [29,30].