Enhanced Adsorption of Alkyl Glucosides on the Silica/Water Interface by Addition of Amine Oxides
2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 7, 2766-2772 p.Article in journal (Refereed) Published
The effect of adding a small amount of dodecyl dimethylamine oxide (DDAO) on adsorption on silica from an aqueous solution of dodecyl maltoside (C(12)G(2)) has been investigated. The C(12)G(2) itself does not adsorb significantly on silica at any concentration. DDAO on the other hand readily adsorbs in a bilayer-like structure at concentrations approaching the critical micelle concentration (cmc), but the adsorbed amount at the concentrations it has been applied in these mixtures is small. In contrast, by combination of the two surfactants, significant adsorption is observed at concentrations where the adsorption of the pure DDAO, as well as pure C(12)G(2), is very low. We thus see a strong enhancement of the adsorption from the mixed system. The adsorption is suggested to be a two-step process, where individual DDAO molecules first adsorb to the silica surface through electrostatic interactions, and then C(12)G(2) adsorbs at the hydrophobic sites the DDAO tails constitute through hydrophobic bonding. A minimum concentration of DDAO is required to induce adsorption from a solution with constant C(12)G(2) concentration. This concentration is lower for C(12)G(2) solutions below and equal to cmcC(12)G(2) than above cmc(C12)G(2). In addition, the total adsorbed amount shows a maximum around cmcC(12)G(2) of the mixture for a solution with low DDAO contents. Both these effects are explained by incorporation of DDAO in the mixed micelles above cmc(mix)., which leads to a desorption of DDAO from the surface.
Place, publisher, year, edition, pages
2005. Vol. 21, no 7, 2766-2772 p.
Adsorption, Amines, Chemical bonds, Desorption, Hydrophobicity, Interfaces (materials), Micelles, Oxides, Refractive index, Silica, Water
IdentifiersURN: urn:nbn:se:kth:diva-6509DOI: 10.1021/la049173iISI: 000228042400025ScopusID: 2-s2.0-16244401985OAI: oai:DiVA.org:kth-6509DiVA: diva2:11242
QC 201009132005-09-192005-09-192012-09-24Bibliographically approved