Aqueous phase behavior of the PEO-containing non-ionic surfactant C₁₂E₆: A molecular dynamics simulation study

Non-ionic surfactants containing polyethylene oxide (PEO) chains are widely used in drug formulations, cosmetics, paints, textiles and detergents. High quality molecular dynamics models for PEO surfactants can give us detailed, atomic-scale information about the behavior of surfactant/water mixtures.

We used two molecular dynamics force fields (FFs), 2016H66 and 53A6_DBW, to model the simple non-ionic PEO surfactant, hexaoxyethylene dodecyl ether (C₁₂E₆). We investigated surfactant/water mixtures that span the phase diagram of starting from randomly distributed arrangements. In some cases, we also started with prebuilt, approximate models. The simulations results were compared with the experimentally observed phase behavior.

Overall, this study shows that the spontaneous self-assembly of PEO non-ionic surfactants into different colloidal structures can be accurately modeled with MD simulations using the 2016H66 FF although transitions to well-formed hexagonal phase are slow. Of the two FFs investigated, the 2016H66 FF better reproduces the experimental phase behavior across all regions of the C₁₂E_6/water phase diagram.