Modeling Aggregation of Ionic Surfactants Using a Smeared Charge Approximation in Dissipative Particle Dynamics...

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Surfactant self-assembly into micelles is crucial for various industrial applications.
• Understanding micellization mechanisms requires accurate modeling of complex molecular interactions.

Purpose of the Study:

• To investigate micellization of anionic (SDS) and cationic (CTAB) surfactants and their mixtures using dissipative particle dynamics (DPD) simulations.
• To develop and parameterize coarse-grained models for SDS and CTAB surfactants.

Main Methods:

• Utilized dissipative particle dynamics (DPD) simulations for micellization studies.
• Employed coarse-grained models parameterized by atomistic simulations and activity coefficient calibration.
• Applied a smeared charge approximation for electrostatic interactions of charged beads.

Main Results:

• The models semiquantitatively describe self-assembly of SDS and CTAB solutions with added electrolytes.
• Predicted a decrease in free surfactant concentration with increased loading and salt-induced aggregation transitions.
• Observed sequential transitions to worm-like micelles and vesicles in catanionic SDS-CTAB mixtures.

Conclusions:

• DPD simulations provide a reliable method for studying surfactant self-assembly and predicting critical micelle concentrations.
• The developed models accurately capture the complex aggregation behavior of single-component and mixed surfactant systems.
• The study elucidates the formation of distinct micellar structures (worm-like micelles, vesicles) in catanionic mixtures.