Study of Water−Sodium Dodecyl Sulfate Micellar Solubilization Thermodynamics for Several Solute Homolog Series by Headspace Gas Chromatography

Abstract

We employed headspace gas chromatography to measure water-to-sodium dodecyl sulfate (SDS) micellar partition coefficients for homologous series of n-alkylbenzenes, 1-nitroalkanes, 1-alkanols, and 2-ketones. The free energy of transfer per methylene unit is -612 cal/mol for polar solutes and -534 cal/mol for nonpolar solutes. Henry's law was also explored for the n-alkylbenzenes and 2-ketones and found to hold to total solute mole fractions of at least 7 × 10 -3 and 3.4 × 10 -2 in the SDS micellar phase, respectively. Additionally, we compared water-to-SDS partition coefficients to water-to-bulk organic solvent partition coefficients for methylene units and whole solutes. From these comparisons we conclude that short, polar organic solvents such as methanol and nitromethane make the best models of the solutes' micellar environment and that the solutes and their methylene units are located in the relatively polar palisade and/or Stern layers of the SDS micelles.

Development of an equilibrium headspace gas chromatographic method for the measurement of noncovalent association and partitioning of n-alkylbenzenes at infinite dilution in fulvic acid pseudophase

“…[SDS] t ) is linear with a sharp break at cmc [21,22]. In FA, however, the pre-to post-transition region is not sharp and could involve a step-wise aggregation of FA molecules.…”

“…Change in fugacity of volatile solutes by eHSGC has been used to calculate the association equilibrium constant, critical micelle concentration, partition coefficient, activity coefficients, and transfer free energies of small molecules in micelles and microemulsions [19][20][21][22][23]. Here, we are specifically interested in the noncovalent association of FA with n-alkylbenzenes, as probes, in the concentration range from monomer-FA to FA n -aggregate pseudophase in pure aqueous media.…”

Encapsulation Processes by Bilayer Vesicles

“…81 Theoretical models are, of course, also helpful, as, for example, in studies of the enveloping of charged proteins by lipid bilayers. 25 …”

Solubilization of Polycyclic Aromatic Compounds into n-Decyltrimethylammonium Perfluorocarboxylate Micelles

“…In particular, micellar solution properties are often governed by the latter rather than the former due to their direct contact with the bulk phase on the micellar surface (12). Thus, many papers have appeared concerning the dependence of micellization and solubilization on inorganic or organic counterions of micelles, some of which has a great influence on the properties of micellar solutions (13)(14)(15). We have investigated the solubilization into the micelles of ionic surfactants whose surfactant ion is the same, while the counterions are different in their hydrophobicity (16).…”