Comparing Decyl-β-maltoside and Octaethyleneglycol Mono n-Decyl Ether in Mixed Micelles with Dodecyl Benzenesulfonate: 1. Formation of Mixed Micelles

Abstract

In this study the mixed micelle behavior of an alkyl polyglycoside is compared to a surfactant of polyoxyethylene type, by means of surface tension measurements. The two nonionic surfactants are compared in mixed micelle systems together with an anionic surfactant. The surfactant mixtures are: decyl-β-maltoside (C10M) with dodecyl benzenesulfonate (C12BS) and octaethyleneglycol mono n-decyl ether (C10EO8) with C12BS. The mixture of C10M and C10EO8 is also studied. Critical micelle concentration (CMC) and the concentration at which the surface tension reduction is 20 mNm−1 (C20) are determined at different mixing ratios of the surfactant mixtures. By applying the nonideal mixed micelle theory, interaction parameters at CMC (βCMC) and C20 (βC20) are calculated for the surfactant mixtures. The results show that the C10M–C12BS mixture has a βCMC parameter of −2.1, whereas the βCMC parameter for the C10EO8–C12BS mixture is −3.3, indicating a weaker net attractive interaction between C10M and C12BS than between C10EO8 and C12BS. This is attributed to a small negative and positive charge of the respective nonionic surfactants. This is supported by a slightly negative βCMC parameter obtained for the surfactant mixture C10M–C10EO8, indicating a small net attractive interaction between the two nonionic surfactants.