Computational modelling of surfactant assemblies in apolar solvents: strategies and common pitfalls

Here, we survey computational modelling approaches of surfactant assemblies in apolar solvents, with specific attention to differences and caveats due to the solvent environment being apolar instead of water. Surfactant assembly in apolar solvents rises via specific enthalpic interactions and weak polarity contrasts between the surfactant tails and the solvent. As a computational model construction premise, this is different to the hydrophobicity driven surfactant assembly in aqueous solution, where the loss of solvent entropy is minimized by shielding the apolar tails from water. The difference in the driving forces leads to non-obvious challenges when using models parameterized for aqueous solutions in describing apolar solvent systems. We cover from atomistic to coarse-grained molecular modelling and mesoscale models but also continuum scale approaches, including models of reverse micellar charge transfer. While data-based, machine-learning, approaches to surfactants in apolar solvents remain limited to date, perspective to their potential is provided. Finally, we offer insight to how the currently available modelling approaches that have typically been constructed for accuracy in water solutions should be used to describe accurately also surfactant assembly in apolar solvents and the considerations required.