Light, neutron, X-ray scattering, and conductivity measurements on aqueous dodecyltrimethylammonium bromide/1-hexanol solutions

Abstract

Ternary systems of dodecyltrimethylammonium bromide (C12TAB)/1-hexanol/water are examd. for series with const. surfactant/alc. molar ratios of 8:2, 8:4, 8:6, and 8:8 at surfactant concns. of 6.167-61.67 g/L (0.02-0.20 mol/L). The methods used are cond. measurements, differential refractometry, static and dynamic light scattering, small-angle neutron scattering, and X-ray scattering. Crit. micelle concns. and the degree of dissocn. of the micelles are detd. by cond. measurements. The refractive index increment is given for each series as well as static and dynamic light-scattering intensities plotted as a function of the surfactant concn. From small-angle neutron-scattering expts. a detailed picture of the size and the geometry of the micelles could be obtained, whereas small-angle X-ray scattering allowed information about the thickness of the interfacial film to be inferred. A hypernetted chain calcn. with solvent plus ion-averaged screened Coulombic potentials combined with an ellipsoidal core/shell model permitted a simultaneous and coherent description of all scattering results.