Investigations of Interfacial Properties of Surfactants with Different Structures at the Oil/Water Interface Using Dissipative Particle Dynamics

Abstract

Dissipative particle dynamics (DPD) simulations of monolayers of surfactant with different structures at the oil/water interface are performed. With a simple surfactant model, how variation in surfactant structure influences the interfacial properties and the conformation of surfactant is investigated. The interfacial tension, interfacial thickness, interfacial density, and the orientational order parameters profiles are computed. It is found that the surfactants with two tails or two head groups are significantly more efficient at the oil/water interface if their head groups are strongly hydrophilic. Branched surfactants attain higher interfacial thickness. Simulations of the conformation of surfactant chain indicate that they are straighter and more ordered with interfacial coverage increase. The increase in the number of hydrophobic tails or head groups lowers the stretching and orienting of the surfactant chains. The simulation on the supersaturated surfactant monolayer shows that the process of forming a swollen micelle is not viable in very rigid mono layers.