SOLUBILIZATION EQUILIBRIA OF WATER IN NONAQUEOUS SOLUTIONS OF BLOCK IONOMER REVERSE MICELLES - AN NMR-STUDY

Water can be solubilized into the ionic cores of reverse micelles formed by block ionomers in nonpolar solvents. The distribution coefficients of water in the reverse micellar solutions of polystyrene (440 units)-b-poly(sodium methacrylate) (40 units) were determined from H-1 NMR chemical shift measurements. For different solvents, the partition of water in favor of the reverse micelles occurs in the following order: cyclohexane > toluene is similar to benzene > chloroform >> THF is similar to DMF. From the distribution coefficients, the free energies of transfer of water from the solvent phase to the reverse micelles can be calculated. These free energies of transfer correlate linearly with the free energies of transfer of water from the solvent phase to the water phase, as calculated from the solubility data of water in the solvents. From this linear relationship, the distribution of water can be estimated for reverse micellar systems in other solvents once the solubilities of water in the solvents are known.