Self-Aggregation of Alkyltrimethylammonium Bromides (C₁₀-, C₁₂-, C₁₄-, and C₁₆TAB) and Their Binary Mixtures in Aqueous Medium:  A Critical and Comprehensive Assessment of Interfacial Behavior and Bulk Properties with Reference to Two Types of Micelle Formation

Abstract

The detailed interfacial adsorption and micellization behavior of pure and mixed alkyltrimethylammonium bromides (ATABs: C10-, C12-, C14-, and C16TAB) were studied using tensiometric, conductometric, fluorimetric, viscometric, and calorimetric methods. The critical micellar concentration (CMC), thermodynamics of adsorption and micellization, counterion binding, aggregation number, and micellar polarity were determined. It was observed that the studied 1:1 molar mixtures of C10-C12TAB, C10-C14TAB, and C10-C16TAB, and the mixtures C12-C14TAB and C12-C16TAB at different mole ratios produced two CMCs that were supported by the conductometric, calorimetric and viscometric methods. Compared to the first micelle, the second micelle condensed more counterions and produced a higher aggregation number, but their interior polarity states were the same. The surface excess, area minimum of the ATABs at the CMC and Gibbs free energy of adsorption were evaluated and compared. The ideality/nonideality states of the mixed micelles formed in solution were tested in the light of Clint and Rubingh's formalisms; the mixed systems were found to undergo moderate to weak synergistic interaction. The contributions of the terminal methyl group, the intermediate methylene groups, and the hydrophilic tetramethylammonium group toward the standard Gibbs free energy, enthalpy, and entropy of the micellization processes were deciphered and discussed.

Surface‐Active Properties and Antimicrobial Study of Conventional Cationic and Synthesized Symmetrical Gemini Surfactants

“…It was also observed that with an increase in alkyl chain length of the gemini surfactants, the compounds exhibit a stronger antimicrobial effect due to a more hydrophobic environment and a lower CMC. These findings agree well with the existing reports that if the alkyl chain of quaternary ammonium compounds is shorter, the greater will be the CMC [13,19,26]. As a consequence, the antimicrobial power of 12-2-12 and 12-4-12 proves to be much weaker than the 16-s-16 series [24].…”

“…Sometimes a series of dilutions were made for concentrations in a narrow range. Experiments were carried out in triplicate to determine any change with time and to obtain an average value [25,26].…”

“…The value of n is taken as 2 for the conventional surfactant and 3 for a dimeric surfactant (a divalent surfactant ion and two univalent counterions in the absence of a swamping electrolyte [1,2,26].…”

Studies on the Effect of Amino Acids/Peptide on Micellization of SDS at Different Temperatures

“…A similar decrease in CMC of SDS upon addition of amino acids in aqueous medium has also been reported by others [31]. The degree of ionization (b) of the micelles can be estimated conductometrically from the ratio of the slopes of the two linear segments above and below CMC of specific conductivity versus surfactant concentration [30,37,38] and, hence, the degree of counterion association, is given as a = 1 -b. This simple method is quite satisfactory in providing quantitative estimation of b, as reported by Buckingham and co-workers [39].…”

Effect of Inorganic Additives on a Conventional Anionic–Nonionic Mixed Surfactants System in Aqueous Solution

“…The abundant use of mixed surfactant mixtures is of great importance for industrial purposes as well as is a matter of curiosity for the researchers to understand both the theoretical and practical significance. Much investigation, articles, and research papers have been published on the solution properties of surfactant and mixed surfactants systems in the last three decades [5][6][7][8][9][10][11][12]. A mixed surfactants system exhibits greater surface activity, i.e., lower critical micelle concentration (CMC) values, than that obtained with any of the individual components of the mixture at the same concentration.…”