Computational Study of the Structure and Behavior of Aqueous Mixed System Sodium Unsaturated Carboxylate-dodecyltrimethylammonium Bromide

Abstract

The mixed surfactant system sodium 10-undecenoate (SUD)-dodecyltrimethylammonium bromide (DTAB) was studied by computational simulation to determine the composition and structure of the mixed microstructures. Results were contrasted with experimental data obtained from literature and our own laboratory. The modelization predicts spherical or cylindrical micelles with a preferential composition of SUD-DTAB of about 1:2, while the system predicts a lamellar structure with a proportion of 1:1 when SUD is replaced by the saturated soap sodium undecanoate. The model also predicts the deep inclusion of bromide ions in the micelle Stern layer. All predictions were in agreement with previous experimental results.

Critical Micelle Concentration and HLB of the Sodium Oleate–Hexadecyltrimethylammonium Bromide Mixed System

“…The structure of the interface is composed by carboxylate and trimethyl ammonium ions, but also by double bounds intercalated having water affinity [14,29,47]. The same conformation of oleate ions was also observed at the air-water interface [48] and is probably maintained at the water-oil droplets interface, thus giving a charged interface even at the 1:1 proportion.…”

Effect of Double Bonds in the Formation of Sodium Dodecanoate and Sodium 10-Undecenoate Mixed Micelles in Water

“…4 Computer simulation supports the explanation that the interaction between the π electrons of the double bond and water produces a reduction in energy which is responsible for this behavior. 4,5 In an anionic-anionic mixture (sodium oleate-sodium dehydrocholate) we also have found a behavior which may be caused by this interaction. 6 However, in this case the unusual structure of one of the components (sodium dehydrocholate) may also play a role in the nonideal interaction.…”

“…Cationic−anionic mixtures do not precipitate, even at a 1:1 proportion, and micelles have a preferential proportion which is not that of 1:1, but that which produces the complete substitution of the micelle saturated hydrocarbon/water interface by an unsaturated hydrocarbon/water one. − The presence of the double bond also gives an unusual nonideal behavior of the partial molar volume of mixed micelles, which indicates that the effect is originated in the hydrocarbon micelle core . Computer simulation supports the explanation that the interaction between the π electrons of the double bond and water produces a reduction in energy which is responsible for this behavior. , In an anionic−anionic mixture (sodium oleate−sodium dehydrocholate) we also have found a behavior which may be caused by this interaction . However, in this case the unusual structure of one of the components (sodium dehydrocholate) may also play a role in the nonideal interaction.…”

The aqueous Triton X-100 – dodecyltrimethylammonium bromidemicellar mixed system. Experimental results and thermodynamic analysis

“…Thus the counterions should not be electrostatically attached to the micelles. However, in another mixed system, DTAB-sodium undecenoate (SUD) it was found, that even micelles with compositions that had a SUD content enough to make them negatively charged, there was aggregation of bromide ions to the micelle surface [42], and the same was found in a computer simulation of the same system [43]. This adsorption was attributed to van der Waals adsorption of Brions to the micelle-solution interface, due to the high polarizability of this ion.…”