The effect of hydrophobicity on the dissolution of surfactant lamellar phases

Formulated products are essential in our daily life. They are available everyway we look from toothpaste to salad dressing and from motor oil to make up. These products seem different but they share common components like oil, water, particles and surfactants. The main goal of this study is to provide further insight into surfactant dissolution process by studying the effect of changing the final concentration of surfactants and the degree of surfactant hydrophobicity. To achieve this goal dissipative particle dynamic (DPD) simulations were used. The simulated system contained surfactant molecules in solvent at 80%, which initially form a lamellar phase. The dissolution process is investigated by placing this lamellar phase of surfactant next to a box of water. Results show that the lamellar phase transforms into a micellar phase at a faster rate than the full diffusion of these micelles through the box. This two-stage dissolution process can be represented as a simple model with a transformation parameter and a diffusion parameter; both of which decrease with increasing hydrophobicity but are box size independent. Dissolution of the surfactant with higher hydrophobicity produces micelles, which are more elongated and worm-like in nature whereas lower hydrophobicity produces spherical micelles.

Automated summary

Formulated products are essential in our daily life and often contain common components like oil, water, particles, and surfactants. The main aim of this study is to gain further insight into surfactant dissolution process by changing the concentration and hydrophobicity of surfactants. Results indicate that higher hydrophobicity of surfactants results in the formation of elongated worm-like micelles, while lower hydrophobicity produces spherical micelles, during the dissolution process.