The effect of changing the molecular structure of the surfactant on the dissolution of lamellar phases

Dissolution processes of surfactants, especially when in the lamellar phase, into water are important for product formulation. Understanding this process at a molecular level will help to enhance product design and control surfactant processes. The main goal of this study is to examine the effect of different lengths of surfactants and the hydrophobic to hydrophilic ratio on the dissolution process of surfactants. To achieve this goal dissipative particle dynamic (DPD) simulations were used. Lamellar equilibrium simu-lations were carried out for different surfactant chain lengths at 80 vol% with water. The surfactant chains were each run in a simulation box of dimensions 20 x 20 x 20 until equilibrium was reached. The lamel-lar phase formed for all different surfactant chain lengths and, after the initial equilibrium the surfactant systems were then simulated with a water box for dissolution. The dissolution process was tracked by visual analysis, local concentration analysis, micelle size, and a zonal model to calculate the diffusion parameter.Results show that as the surfactant chain length increased by adding more of the hydrophobic beads, the dissolution process slowed down. Increasing the hydrophilic part of the surfactant speeds up the dis-solution process, but the effect of adding more of the hydrophobic part is greater than the effect of adding more of the hydrophilic part on the dissolution process.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

The purpose of this study is to investigate the impact of surfactant chain length and hydrophobic to hydrophilic ratio on the dissolution process. The results show that increasing the length of the hydrophobic part slows down the dissolution process, while increasing the length of the hydrophilic part speeds it up. However, the effect of adding more hydrophobic beads is greater than that of adding more hydrophilic beads on the dissolution process.