Calorimetric and NMR investigations of the micellar properties of sodium dodecyl sulfate in aqueous mixtures of isomeric butanediols

The enthalpies (Delta(mic)H degrees), entropies (Delta(mic)S degrees), and Gibbs energies (Delta(mic)G degrees) of micelle formation have been determi ned for a series of sodium dodecyl sulfate (SDS)/butanediol isomer micelles using isoperibol solution calorimetry. Nuclear magnetic resonance (NMR) pa ramagnetic relaxation enhancement experiments were used to determine the de gree of solubilization of the isomeric butanediols (BTDs) in a 0.100 M solu tion of SDS micelles. In addition, the manner in which the butanediol cosol vents interact with SDS micelles, as a function of the position of substitu tion of the hydroxyl groups on the four-carbon backbone, has been examined closely via C-13 NMR spectroscopy. All of these results are interpreted in terms of the differences in the interaction of the isomeric butanediols wit h SDS micelles because of the addition of the second hydroxyl headgroup on the four-carbon backbone of the alcohol, when compared to the well-studied SDS/1-butanol (C4OH) mixed micellar system.