From micelle to microemulsion: an investigation of structural changes using molecular dynamics

Abstract

Objective Although a huge number of experimental works may be observed in the literature for microemulsions, modelling reports onthese nano-systems are rare. Additionally, no comprehensive work so far has detailed the changes occurring to a micellar droplet when oilmolecules are introduced (i.e. obtaining microemulsions from micelles). This work aimed to simulate a micelle and a microemulsion systemcontaining polysorbate 80 - as surfactant - and study the structural changes in the two systems.Methods Molecular dynamics simulation employing a coarse-grained model was used.Results The results showed that the oil molecules located in the hydrophobic core of the micelle make its size larger, while the co-surfactantmolecules distribute throughout the system and enter the hydrophilic shell of the micelle.Conclusion It was shown that insertion of oil molecules makes the droplets more spherical, while co-surfactants tend to enlarge them.

Review on Microemulsions for Conformance Improvement Technology: Fundamentals, Design Considerations, and Perspectives

“…On the basis of experimental and molecular simulation studies, it is evident that a surfactant must be sufficiently hydrophilic and hydrophobic to form a stable, functional microemulsion. , If a surfactant is too hydrophilic, it will interact with aqueous molecules to form a Winsor I phase, which may lead to high IFT values. On the contrary, a too hydrophobic surfactant can carry and displace oil molecules but lacks the necessary “high viscosity” under dynamic shear to plug desirable zones and, thus, exhibits a favorable sweep through previously unexplored regions.…”