E. Caponetti, R. Triolo, P. C. Ho
Mar 1, 1987
Citations
0
Influential Citations
18
Citations
Journal
Journal of Colloid and Interface Science
Abstract
Abstract Sodium p-n-dodecylbenzenesulfonate solutions have been studied by means of small angle neutron scattering measurements at 65°C as a function of the surfactant concentration, as a function of the contrast of the solvent, and as a function of the concentration of added electrolyte. In addition micelles of the isomeric branched chain surfactant sodium p-1-(pentylheptyl)benzenesulfonate have been studied at the same temperature as a function of the contrast of the solvent and as a function of the concentration of added electrolyte to compare the structure and the micellar growth of the two surfactants. Good fits to the experimental results have been obtained by calculating the structure factor by means of the mean spherical approximation using a screened coulombic potential plus hard-core repulsions. Several different models have been used to calculate the particle form factor. For some of the models, the measured geometry and the charge of the aggregates are, within the experimental uncertainties, independent of the contrast between the micelles and the solvent. The thickness of the shell which surrounds the hydrocarbon core implies a rough micellar surface for both surfactants; thus we propose that the planar phenyl group functions as a sort of supplementary head group, leading to a thicker polar shell.