Abstract
This review was introduced on the recent studies of thermodynamic arguments for equilibrium penetration. Two penetration systems, especially, which were composed of L-α, β-dimyristoyllecithinN-dodecyl-β-alanine (NDA) surfactant and α, α'-dilaurin NDA were described in detail. The characteristics in investigation of these systems was that adsorbed amount of surfactant was directly measured by a radiotracer technique using tritium-labeled compounds at solution surface with and without the spread monolayers. The molecular complex formation of lecithin and NDA was precisely explained how to be analyzed from the enthalpy changes of spread films and adsorbed surfactant in penetration at water surface.
