Ternary oil—water—amphiphile systems: self-assembly and phase equilibria

Abstract

The micellization properties and phase behavior of model ternary surfactant -oil -water systems were studied by grand-canonical Monte Carlo simulations assisted by histogramreweighting techniques. Larson's lattice model was used for a symmetrical H 4 T 4 surfactant, where H represents hydrophilic and T hydrophobic groups. In contrast to earlier studies, we studied oil chains of variable length, from T to T 4 , and determined quantitatively the effect of added oil on the critical micelle concentration (cmc). It was found that the cmc decreases as the volume fraction of oil in the aqueous phase is increased. Longer oil chains have a stronger effect than shorter chains at the same volume fraction. The oil, tail and head density profiles were obtained for typical micelles. Simulation results for the density profiles indicate that long-chain oils are almost exclusively located within the micellar aggregates, in agreement with single-chain mean-field theory predictions. Ternary phase diagrams were obtained both by simulations and by quasichemical theory. The results suggest that the critical micelle concentration line is directed towards the oil-lean corner of the three-phase triangle, if there is one present in the system. It was also found that the amount of oil that can be dissolved in the ternary system increases sharply at the surfactant critical micelle concentration, indicating that micellization greatly enhances oil solubility.

Computer simulation of adsorption kinetics of surfactants on solid surfaces

“…By connecting the model with other computer simulation techniques [16][17][18][19][20][21][22][23], the Larson model was widely used to study the micellization and phase equilibria of surfactant systems [16][17][18][19] and micelle formation dynamics [20,21]. In addition, by introducing shear flow, the behavior of confined cylindrical micelle-forming surfactants was investigated using Lattice MC [22,23].…”

Monte Carlo simulations of amphiphilic nanoparticle self-assembly

“…Additionally, the transitions involved in binary mixtures of amphiphiles could be studied by extending the methods used here and in previous work 64 to examine the dissolution of bilayers by structures that form spherical micelles. Recent interest in mixtures of diblock copolymers and nanoparticles 65,66 suggests another avenue of potential work with regard to mixture simulations.…”

Self-assembly of amphiphilic molecules: A review on the recent computer simulation results

“…Several reviews on the simulation of surfactant solutions have appeared in the literature [54][55][56]. Some recent advances on the surfactant self-assembly were reported by Panagiotopolous and his co-workers [57][58][59][60][61][62]. They used Larson's model to study the micellization and phase equilibria of surfactant systems [57][58][59][60] and micelle formation dynamics [61,62].…”

“…Some recent advances on the surfactant self-assembly were reported by Panagiotopolous and his co-workers [57][58][59][60][61][62]. They used Larson's model to study the micellization and phase equilibria of surfactant systems [57][58][59][60] and micelle formation dynamics [61,62]. Molecular dynamics (MD) simulations also seem to be straightforward for the investigation the self-assembly process, although they suffer from the short accessible length and time scales which often prevent us from getting meaningful results with statistical average.…”