Solubilization-Site-Dependent Micellar Morphology: Effect of Organic Additives and Quaternary Ammonium Bromides

Abstract

Here we report systematic viscosity measurements under Newtonian flow conditions for sodium dodecyl sulfate (SDS) micellar solutions in the presence of aliphatic hydrocarbons (n-hexane, n-heptane, n-octane), toluene, and 1-alkanols (1-heptanol, 1-octanol) at 30 °C. The influence of 0.1 M quaternary ammonium bromides (R4NBr; R ) H, CH3, C2H5, n-C3H7, n-C4H9, n-C5H11) was seen on relative viscosity (ηr) vs additive concentration profiles. Lower members of R4NBr (R ) H, CH3, C2H5) have marginal influence on viscosity profiles and hence on micellar morphology. This may be due to the less pronounced effect on association structures as well as on solubilization sites (and on solubilizate content at a particular site) of added organics. As the alkyl part of R4NBr was increased (R g n-C3H7), the effect, which depended upon the nature of the additive (i.e., its hydrophobic/polarity character), was significant. This is possibly due to salts affecting the partitioning content of organic additives at different micellar solubilization sites with concomitant changes in micellar morphology, as well as viscosity of the micellar solutions. The effect of tetra-n-butylammonium bromide (R ) n-C4H9) concentration was seen to substantiate the change in site of solubilization phenomenon of organic additives. These studies show that, with an appropriate R4NBr concentration present in combination with a surfactant, change of solubilization site even for nonpolar compounds (like hydrocarbons) is possible.

Submicellar aggregates in aqueous sodium dodecyl sulphate solutions: Investigations by dynamic light scattering and water penetration through porous media

“…These observations are in good agreement with the data obtained as a function of SDS and added NaCl concentration. The aggregation behavior of SDS in aqueous solution in the presence of various organic additives is well documented [24][25][26]. The solubilization of alcohols in SDS micelles and subsequent effect to micellization and morphological features is investigated by different analytical methods [27][28][29][30].…”

Solution and surface properties of amphiphilic drug – nonelectrolyte systems

“…The effect of alcohols on the properties of surfactants has been extensively studied [12][13][14][15][16][17][18][19][20][21]. The partitioning of alcohols between the aqueous and micellar phases depends upon the nature and concentration of alcohols.…”

Effects of surfactants on the transport properties of redox species through Nafion® membranes

“…Although tetraalkylammonium salts were a reasonable first choice for tailoring the chemical and physical properties of Nafion ® due to literature reports of tetraalkylammonium salts inducing growth of micelles [9,10], they are not necessarily the ideal ammonium salt for tailoring the chemical and physical properties of the micellar pore structure. Research has shown that maximum micellar stability occurs when the chain lengths of the both the main micellar component and the surfactant are the same in sodium dodecyl sulfate micelles (SDS) [11].…”