The phase diagram was determined for the system water, phenethyl alcohol and a commercial surfactant, Laureth 4 (Brij® 30), and the vapor pressure of phenethyl alcohol (PEA) measured in the entire system. The phase diagram showed complete solubility of the surfactant and the phenethyl alcohol with limited solubilization of water. The water was dissolved into the surfactant forming a surfactant solution and a lamellar liquid crystal.
The variation of vapor pressure for the solutions was related to the surfactant self-association and to the formation of inverse micelles. The Henry’s constant was 1.5 for PEA in the surfactant and increased systematically for the different phases to a value of approximately 103 for water.