Interfacial properties of surfactant mixtures with alkyl polyglycosides

Abstract

Alkyl monoglycosides and polyglycosides (APG) are characterized in terms of their interfacial properties which exhibit a dependence on alkyl chain length and degree of polymerization. A comparison is drawn to other nonionic and anionic surfactants. In hard water, clouding phenomena are observed for C8/10 and C12/14 APG. The critical micelle concentrations (CMC) of the alkylglycosides are similar to those of other nonionic surfactants and show a decrease with increasin galkyl chain length. The degree of polymeriization has only a minor influence on the CMC. Above the CMC, alkylglycosides exhibit very low interfacial tensions against mineral oil compared to C12/14 fatty alcohol sulfate (C12/14 FAS). In contrast to C12/14 FAS and C12/14 fatty alcohol hexaglycol ether, respectively, C12/14 APG shows remarakbly high dynamic surface tensions even at a concentration far above the CMC. For mixtures of C12/14 APG and C12/14 FAS the static surface tensions and the CMC lie close to those of C12/14 APG, whereas the dynamic surface tension behavior is dominated by the anionic surfactant.