Surface Activity, Micelle Formation, and Growth of n-Octyl-β- d -Thioglucopyranoside in Aqueous Solutions at Different Temperatures

Micellization, surface activity, and structures of the aggregates of the nonionic surfactant n -octyl-β- d -thioglucopyranoside in aqueous solutions through a temperature range have been investigated. By using surface tension measurements, information was obtained on both changes in the critical micelle concentration and adsorption behavior in the air−liquid interface with the temperature. These data were used to obtain the thermodynamic properties of micellization along with the corresponding adsorption parameters in the air−liquid interface. The results obtained indicated that the surfactant headgroup has a more pronounced hydrophilic character than that of the common polyoxyethylenic nonionic surfactants. Size and structure of the micelles formed at different temperatures were investigated by light scattering measurements. The light scattering data, including static and dynamic experiments, account for micelle growth and hydration. The analysis of the experimental results was focused on the phase transition from sphere to rodlike structures. To corroborate this point, additional measurements of density and intramolecular excimer formation of 1,2-dypyrenylpropane versus the surfactant concentration were performed. Satisfactory agreement of the results, showing a significant micellar growth starting from a certain surfactant concentration, was observed by means of the different techniques used.