Rôle de l'alcool dans les microemulsions. II. Volumes et capacités calorifiques molaires apparents du système eau + dodécylsulfate de sodium + isopropanol à 298,15 K

Abstract

Densities and heat capacities per unit volume of the ternary system: water + sodium dodecylsulfate (NaDS) + isopropanol (iPrOH) have been measured as a function of concentration of alcohol and surfactant at 298.15 K. Apparent and partial molar volumes and heat capacities of isopropanol have been derived therefrom. These quantities reflect the behavior of alcohol in the solution. The results confirm that in the dilute region, iPrOH is partially solubilized in the micelles and contributes to the formation of mixed micelles, and that in the concentrated alcohol region, iPrOH is solubilized in microaggregates of alcohol. The variation of apparent heat capacity at infinite dilution of iPrOH as a function of NaDS concentration shows the existence of a transition in the micellar structure around 0.3 m.