Controlling surfactant self-assembly in dodecane via applied potential*

The response of colloidal assemblies in apolar solvents to applied electrostatic potential plays a key role in both electrostatic stabilization and manipulation of the resulting nanoemulsion, drug delivery, and synthesis platforms. Here, we present a molecular modelling study of the aggregation of dioctyl sodium sulfosuccinate (AOT) surfactant in apolar dodecane solvent under applied potential. We probe the sensitivity of the self-assembling, reverse micellar surfactant structures and their dynamics to the magnitude of the applied potential and presence of moisture in the system. While the anionic AOT surfactant readily forms reverse micellar aggregates even in the absence of trace water, presence of moisture greatly increases the size of the formed aggregates and their dynamics. The applied potential controls the AOT sodium counterion mobility but the charge transfer via the counterions is also influenced strongly by the degree of hydration of the AOT head groups. We discuss the significance of the findings against literature and experimental data.