Structure/performance relationships in long chain dimethylamine oxide/sodium dodecylsulfate surfactant mixtures

Abstract

Dramatic differences in the structure of mixed micelles of long chain amine oxides and sodium dodecylsulfate are noted as a function of composition. In the L1 micellar pseudophase, a sphere-to-rod transition driven by ion-dipole interactions between the dissimilar headgroups leads to synergisms in aqueous solution thickening, Ross-Miles foaming, and nonpolar oil solubilization. For example, an astounding seven orders of magnitude increase in the zero shear viscosity and viscoelastic properties are observed at a single total surfactant concentration. The sphere-to-rod transition can be viewed in FT-IR by examining both the CH2 stretching for the methylene tails, and the S-O stretching modes for the sulfate headgroups.

A Fourier Transform IR Study of the Phase Transitions and Molecular Order in the Hexadecyltrimethylammonium Sulfate/Water System

“…Thus it can be inferred that the conformational properties of the hydrocarbon chains and the headgroup, and the short-n s (CH 2 ) toward lower wave number by about 1 cm 01 (from 2853 to 2852 cm 01 ). A similar observation was made in the range interaction between the surfactant molecules in these two phases are very similar, despite significant differences alkyldimethylamine oxide/SDS system (26). A shift in the same direction was also observed for n as CH 2 .…”

Micellar Interactions in Nonionic/Ionic Mixed Surfactant Systems

“…The reason for such behavior could be that the compact sulfate group in SDS can induce much stronger ion-dipole interactions with the ethylene oxide group as compared to bulky alkylammonium groups characteristic of cationic surfactants (2). This is, for example, the most probable reason why the binding between the EO chain and the SDS group is stronger than that between the EO chain and the pyridinium group in the C 12 E 6 /dodecylpyridinium chloride mixed micelles (30,31). To investigate the effect of the nonionic headgroup on the interactions between the nonionic and anionic headgroups in more detail, further studies were carried out with mixtures of DDAO and SDS.…”

Interaction Between an Anionic and an Amphoteric Surfactant. Part I: Monomer–Micelle Equilibrium

“…The solution properties of amine oxide surfactants are also affected by the presence of other surfactants [17][18][19][20][21][22][23][24][25]. The absolute value of the surface potential of mixed micelles can increase when anionic surfactants are added to amine oxide [26].…”