DIELECTRIC BEHAVIOR OF OCTYL BETA-D-GLUCOPYRANOSIDE MICELLES IN WATERAND IN WATER-GLYCINE SOLUTIONS

The dielectric permittivity, viscosity, and density of octyl beta-D-gl ucopyranoside (OBG)and glycine (G) aqueous solutions, with different O BG/G molecular ratios, were measured as a function of surfactant conce ntration and temperature in order to investigate the effect of the ami no acid on the surface of glucoside micelles. The amino acid shows an appreciable influence on the thermodynamic stability of the surfactant aggregates. However viscometric, volumetric, and dielectric results i ndicate that glycine is not involved in the micellar surface. Such a r esult indicates that the stabilization of the OB;G micellar assemblies , previously observed, is mainly due to the reduction of the solubilit y of the hydrocarbon tail and/or to an increase of the interfacial ten sion between the micellar oil core and the solvent rather than to shor t-range interactions between glycine and OBG polar head groups.