MISCIBILITY OF ETHANOL AND 2-(OCTYLSULFINYL)ETHANOL IN THE ADSORBED FILM AT THE WATER AIR INTERFACE AND IN THE MICELLE

The surface tension of the aqueous solution of the ethanol-2-(octylsulfinyl)ethanol mixture has been measured as a function of total concentration and composition. Total surface density, mole fraction in the adsorbed film, and mole fraction in the micelle have been evaluated by applying the thermodynamic method of surfactant mixture developed previously to the experimental data. The total surface density of the mixture has been found to be similar to that of 2-(octylsulfinyl)ethanol; this has been ascribed to the domination of 2-(octylsulfinyl)ethanol in adsorption. This observation has been justified by the fact that the mole fraction of 2-(octylsulfinyl)ethanol in the adsorbed film is much larger than that in the bulk solution and a little larger than unity. Furthermore, the mole fraction of 2-(octylsulfinyl)ethanol in the micelle has been found to be nearly the same as that in the adsorbed film at the critical micelle concentration. It has been clarified that the ethanol-2-(octylsulfinyl)ethanol mixture is quite different in miscibility in the adsorbed film and micelle from the 1-octanol-2-(octylsulfinyl)ethanol mixture. © 1992.