Molecular Thermodynamics of Micellization: Micelle Size Distributions and Geometry Transitions

Abstract

-Surfactants are amphiphilic molecules that can spontaneously self-assemble in solution, forming structures known as micelles. Variations in temperature, pH, and electrolyte concentration imply changes in the interactions between surfactants and micelle stability conditions, including micelle size distribution and micelle shape. Here, molecular thermodynamics is used to describe and predict conditions of micelle formation in surfactant solutions by directly calculating the minimum Gibbs free energy of the system, corresponding to the most stable condition of the surfactant solution. In order to find it, the proposed methodology takes into account the micelle size distribution and two possible geometries (spherical and spherocylindrical). We propose a numerical optimization methodology where the minimum free energy can be reached faster and in a more reliable way. The proposed models predict the critical micelle concentration well when compared to experimental data, and also predict the effect of salt on micelle geometry transitions.

The effect of sonication on the ion exchange constant, KXBr of CTABr/chlorobenz

“…Micelles are known to play prominent roles in many processes in both fundamental and applied science. The dissolution of micelle monomers above its critical micelle concentration and Kraft temperature will result in aggregations as a mean to achieve their thermodynamic stability when exposed to solvents [1] , [2] , [3] , [4] , [5] . Their ability to protect the hydrophobic tails in aqueous medium allows remarkable solubilizing properties of hydrophobic molecules [6] , [7] .…”

“…Though micelles are known to form spherical structures, they can aggregate to form various structures as their attempt to minimize their free energies [1] , [2] . As they grow, the water like solution gradually becomes more viscous.…”

Nanodrug Delivery Systems for the Treatment of Ovarian Cancer

“…Nanomicelles are classified into three key distinct nanosystems i.e., colloidal nanomicelles formulated from an aggregation of polar and nonpolar molecules in an aqueous solution (amphiphilic aggregates), polyionic nanomicelles formulated from oppositely charged polymers generating an agglomeration due to electrostatic interaction, and nanomicelles originating from metal complexation [63][64][65][66].…”

“…Amphiphilic colloidal nanomicelles are formed from hydrophobic interactions between the inner core and the outer shell of the surfactant molecules in a solution [60]. An active surfactant retains amphiphilic configurations, comprised of hydrophobic and hydrophilic functional groups [66]. The hydrophilic groups form the polar clusters constructed from several moieties including ionised carboxyl, conjugated sulfonate, ammonium, active hydroxyl and amides.…”

The Role of Surfactants in Liquid Soaps and Its Antimicrobial Properties

“…Nonionic surfactants have very low values of CMC and their micelles are larger than those of ionic surfactants. Several thermodynamic and transport properties of surfactant solutions are affected by the size and shape of micelles (Santos et al, 2016). The dual characteristics of surfactant molecules give them a wide range of properties connected to adsorption at interfaces and self-assembly in bulk solution.…”