INVESTIGATION OF MICELLE STRUCTURE BY FLUORINE MAGNETIC RESONANCE .3. EFFECT OF ORGANIC ADDITIVES ON SODIUM 12,12,12-TRIFLUORODODECYL SULFATE SOLUTIONS

Sodium 12,12,12-trifluorododecyl sulfate has been prepared, and its fluorine chemical shift has been determined as a function of concentration in water and in mixed solvents including aqueous urea, glycine, glycerol, acetamide, methanol, acetone, ethanol, dioxane, and tetrahydrofuran. The critical micelle concentration of the fluorinated detergent depends on the solvent composition in much the same way as that of sodium dodecyl sulfate. Observed variations in the chemical shift for the monomeric species are not simply related to changes in the dielectric constant or refractive index of the solvent mixture. The additive effects on the monomer and micelle shifts together give an indication of the degree of penetration of additive into the micelles. Changes in the shapes of the dilution-shift curves show that additives strongly influence the micellar molecular weights, and in some cases the aggregation numbers are reduced to values less than five.