ULTRASONIC-ABSORPTION STUDIES OF SURFACTANT EXCHANGE BETWEEN MICELLES AND BULK PHASE IN AQUEOUS MICELLAR SOLUTIONS OF NONIONIC SURFACTANTS WITH A SHORT ALKYL CHAIN .3. SURFACTANTS WITH A SUGAR HEAD GROUP

Spectrofluorimetry (with pyrene as a probe), ultrasonic absorption measurements, and time-resolved fluorescence quenching have been used to obtain the critical micelle concentration (cmc) and the micelle aggregation number N of four surfactants with a sugar head group: the octyl and thiooctyl glucosides, the 6-O-(N-heptylcarbamoyl)methyl-alpha-D-glucopyranoside (Hecameg), and the octanoyl-N-methylglucamide (Mega-8). The ultrasonic relaxation method has been used to investigate the kinetics of the exchange of these surfactants between micelles and bulk phase. The results have been found to obey the theory of Aniansson and Wall (J. Phys. Chem. 1975, 79, 857) for micellization kinetics. As for the other two series of nonionic surfactants investigated in parts 1 and 2 in this series and as for ionic surfactants, the results showed that the association of the sugar surfactant to their micelles is nearly diffusion-controlled. The change of the rate constant k- for the dissociation of the sugar surfactants from their micelles closely follows the variation of the cmc. Also in the range 25-40-degrees-C the effect of temperature is not very large. The micelle polydispersity is low (polydispersity index 1.01-1.03) as in the case of the other ionic and nonionic surfactants investigated thus far.