The Clouding Phenomenon for Anionic Sodium Dodecyl Sulfate + Quaternary Bromides in Polar Nonaqueous‐Water‐Mixed Solvents

Abstract

Aqueous sodium dodecyl sulfate (SDS) solutions show clouding in the presence of tetra-n-butylammonium bromide (TBAB) and tetra-n-butylphosphonium bromide (TBPB). In this study, we report the effect of various volume percents of different polar nonaqueous solvents (acetonitrile, AN; dimethylsulfoxide, DMSO; methyl ethylene glycol ether, MC; formamide, FA; ethylene glycol, EG) on the clouding behavior of SDS ? quaternary bromide (TBAB or TBPB) systems. The cloud point (CP) was found to decrease with initial increase in the volume percent of the above solvents in mixtures (with water). After a minimum in CP vs. volume percent plots, further increase in the volume percent caused an increase in the CP, followed by a near constant region. The data have been discussed on the basis of the effect of the above solvents on the two types of water present in the system: hydrated water and bulk water. As AN had shown a gradual decrease in the CP to a larger volume percent, it was chosen for detailed studies. Compared to TBAB, TBPB has diminished the effect of AN on CP increase due to its bigger size. The limited CMC data also run parallel to CP results.

Modulation of Aggregation Behaviour of Anionic Surfactant in the Presence of Aqueous Quaternary Ammonium Salts

“…However, the presence of hydrocarbon chains in the case of quaternary ammonium salts may result in penetration of some of the alkyl chains into the micellar core of the surfactant as a result of hydrophobic interactions. The remarkable decrease in CMC of the surfactant as the size of the alkyl chain increases also supports the dominance of hydrophobic interactions [11,[28][29][30].…”

Study of Micellization of Sodium Dodecyl Sulfate in Non‐Aqueous Media Containing Lauric Acid and Dimethylsulfoxide

“…In ionic surfactants, especially, the repulsive forces originate primarily from electrostatic repulsion between the polar head groups, whereas attractive interactions have generally been attributed to hydrophobic interactions between the nonpolar tails of the surfactant monomers [4][5][6]. Understanding the factors that control the self-assembly of amphiphilic molecules is central to a wide range of applications [7,8]. Amphiphiles are able to form aggregates only when they are present in a suitable solvent.…”