B. Kronberg et al., THERMODYNAMICS OF THE HYDROPHOBIC EFFECT IN SURFACTANT SOLUTIONS - MICELLIZATION AND ADSORPTION, Pure and applied chemistry, 67(6), 1995, pp. 897-902
The thermodynamics of surfactant micellization and adsorption onto hyd
rophobic surfaces are examined. The ideal and the Flory-Huggins approx
imations for the combinatorial entropy of transfer are contrasted. Two
main contributions for the Gibbs free energy of transfer from the aqu
eous solution to the micelle or the surface are considered. The first
is the collapse of the water cavity left behind when the solute is tra
nsferred and the second is the destruction of the water structuring ar
ound the solute. It is the balance between these two contributions whi
ch causes the minimum in critical micelle concentration and the maximu
m in adsorption of ionic surfactants with temperature. Separation of t
hese two contributions is achieved using a two-state model recently re
ported for water molecules around nonpolar solutes.