Dielectric behavior of octyl beta-D-glucopyranoside micelles in water and in water-glycine solutions

The dielectric permittivity, viscosity, and density of octyl beta-D-glucopyranoside (OBG)and glycine (G) aqueous solutions, with different OBG/G molecular ratios, were measured as a function of surfactant concentration and temperature in order to investigate the effect of the amino 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 indicate that glycine is not involved in the micellar surface. Such a result indicates that the stabilization of the OB;G micellar assemblies, previously observed, is mainly due to the reduction of the solubility of the hydrocarbon tail and/or to an increase of the interfacial tension between the micellar oil core and the solvent rather than to short-range interactions between glycine and OBG polar head groups.