Physicochemical Studies of Octadecyltrimethylammonium Bromide:  A Critical Assessment of Its Solution Behavior with Reference to Formation of Micelle, and Microemulsion with n-Butanol and n-Heptane

Abstract

Octadecyl-trimethyl-ammonium bromide (C18TAB) is a much less studied representative in the alkyltrimethylammonium halide surfactant series. A comprehensive study of its normal and reverse micelle (microemulsion) formation has been herein conducted by the methods of conductometry, tensiometry, fluorimetry, and microcalorimetry. The energetics of its air/liquid interfacial adsorption and self-association in aqueous solution have been examined. The phase behavior of its combinations with water, n-butanol, and n-heptane in the formation of microemulsions have been investigated with identification of a variety of phases. The energetics of formation of water dispersion in oil (w/o) has been evaluated from dilution experiments conducted at different temperatures. From the results, structural parameters of the droplets have been determined at different [water]/[surfactant] mole ratios (omega) and temperatures. The w/o dispersions have evidenced both volume- and temperature-induced conductance percolation. The results have been treated in light of the Scaling equations, and the associated parameters for the process have been determined. The activation energies for the temperature-induced percolation process of the w/o dispersion have been evaluated and assessed.

Physicochemical studies on ion-pair amphiphiles: Solution and interfacial behaviour of systems derived from sodium dodecylsulfate and n-alkyltrimethylammonium bromide homologues

“…The terminal ω′,ω -CH 3 protons of all the IPAs showed a triplet at about 0⋅88 ppm except for C 12 TA + DS -, which showed the same at 0⋅86 ppm. The α-CH 2 protons and methyl protons of trimethylammonium group of C 18 TA + DS -produced an upfield shift of ~ 0⋅2 and 0⋅14 ppm with respect to the pure cationic surfactant (C 18 TAB) 39 at the same molar concentration which arose due to changes in the electrostatic field in these surfactants (as Br -of C 18 TAB was replaced by DS -). 33,40 As the other protons were far away from the head groups, no observable changes could be found after coacervation.…”

Physicochemistry of hexadecylammonium bromide and its methyl and ethanolic head group analogues in buffered aqueous and gelatin solution

“…It is seen that the weakly soluble N-octyl-N,N,N-trimethylammonium bromide (OM 3 AB) produces cmc values comparable with the Group B surfactants. 67 The addition of ethanolic group on the amphiphile head has two opposing effects on the cmc. It decreases the cmc due to the shielding of the charged head group to interact with its neighbours.…”

Amphiphile self-aggregation: An attempt to reconcile the agreement–disagreement between the enthalpies of micellization determined by the van’t Hoff and Calorimetry methods

“…It is a dependable physical method to study the process of micellization [42]. There are numerous available literature that have used ITC for amphiphile aggregation [1][2][3][4][5]23,[31][32][33]35,[41][42][43][44][45][46][47], thermodynamics of bilayers-to-micelle transition [48,49], amphiphile interaction with polymers and macromolecules [50][51][52][53][54][55][56][57], characterization of protein solution [58], binding of small molecules with biopolymers [59][60][61], interaction of microemulsion with vesicles [62], determination of second virial coefficient of ionic liquid microemulsion [63], kinetics of reaction [64], etc. We have also used the method and have shown a general way of data treatment for microheterogeneous systems like micelles [65] and microemulsions [66].…”

“…Its determination can be done in two ways: (1) by way of quantitative evaluation of the equilibrium constant at different temperatures and their processing through van't Hoff (VH) equation, and (2) by its direct measurement in a calorimeter [1][2][3][4][5][6][7]. Although a comparison between the two sets of results is required for complete energetic information, it is scarcely done in practice.…”