Phase Behavior and Solubilization in Surfactant−Solute−Solvent Systems by Monte Carlo Simulations

Abstract

We use a lattice-based Monte Carlo method presented recently for micellar solubilization (Talsania et al. J. Colloid Interface Sci. 1997, 190, 92) to determine the phase behavior in surfactant-solute-solvent systems and to examine the locus and extent of solubilization of solutes in micelles as a function of the solute hydrophobicity and chain length. A novel method, based on the distribution of solute in clusters of different sizes, is developed to study the phase behavior of the solute in the absence and presence of surfactant. The results obtained from these simulations are compared with estimates based on quasichemical theory to determine the applicability of this theory to micellar systems. Addition of surfactant to a solutesolvent system first leads to a decrease in the solubility of the solutes prior to a subsequent increase at higher surfactant concentrations. An examination of micellar shapes shows that the surfactant studied forms roughly spherical micelles. However, the presence of solute induces coexistence of spherical and oblong micelles.

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

“…we studied, essentially all of the T 4 oil was found associated with micelles. The partition coefficients rapidly increase with increasing oil chain length and increase only weakly with overall surfactant concentration, as also observed for other systems in previous studies [17]. …”

“…A significant difference from previous studies of ternary oil-water-amphiphile systems [15][16][17]38] is that we also consider oil models consisting of chains rather than single sites. In addition, we place particular attention on the relationship between micelle formation and macroscopic phase separation.…”

“…For example, the rich phase behavior of liquid crystals was observed [10,11,[13][14][15] for high concentrations of amphiphile from Monte Carlo studies of a lattice model of ternary oil-water-amphiphile systems. The phase behavior of oil-water-amphiphile systems has been investigated [15][16][17]38] by Monte Carlo simulations and quasichemical theory. Moreover, the formation and properties of micelles were studied extensively for binary solvent-amphiphile systems by Monte Carlo simulations [12,13,[18][19][20][21][22][23][24][25][26][27][28][29] and single-chain mean-field theory (SCMFT) [24,30].…”

Prediction of Surfactants’ Properties using Multiscale Molecular Modeling Tools: A Review

“…There are several works in the literature where MC simulations have been performed in order to study surfactants' aggregation and structure, as well as CMC calculation [14,22,[26][27][28][29][30][31][32]. For instance, Talsania et al [26] have used lattice Monte Carlo to explore the formation and stabilization of micelles with contaminants.…”

“…The CMC is also graphically accessible by representing the concentration of isolated surfactants, (X 1 ), as a function of the total concentration of surfactants, (X T ), see Figure 2. Considering that above the CMC, X 1 = f(X T ) is a decreasing linear function, the CMC can be defined as the intersection of X 1 = −mX T + b and X 1 = X T /2 functions.There are several works in the literature where MC simulations have been performed in order to study surfactants' aggregation and structure, as well as CMC calculation [14,22,[26][27][28][29][30][31][32] [32] in which ionic surfactants have been modeled and electrostatic interaction were included in the lattice model. Molecular Dynamics simulations have been also used to study and predict aggregation, structure and the CMC of surfactants [25, 33-38, 40, 41].…”