Phase Behavior of Alkyl Ethoxylate Surfactants in a Dissipative Particle Dynamics Model

We present a dissipative particle dynamics (DPD) model capable of capturing the liquid state phase behavior of nonionic surfactants from the alkyl ethoxylate (CnEm) family. The model is based upon our recent work [Anderson et al. J. Chem. Phys. 2017, 147, 094503] but adopts tighter control of the molecular structure by setting the bond angles with guidance from molecular dynamics simulations. Changes to the geometry of the surfactants were shown to have little effect on the predicted micelle properties of sampled surfactants, or the water-octanol partition coefficients of small molecules, when compared to the original work. With these modifications the model is capable of reproducing the binary water-surfactant phase behavior of nine surfactants (C8E4, C8E5, C8E6, C10E4, C10E6, C10E8, C12E6, C12E8, and C12E12) with a good degree of accuracy.

Automated summary

We propose a dissipative particle dynamics (DPD) model that can effectively describe the liquid state phase behavior of nonionic surfactants from the alkyl ethoxylate (CnEm) family. The model is an improved version based on previous work and incorporates molecular dynamics simulations to control the molecular structure more accurately. Our results show that changes to the surfactant geometry have minimal impact on the properties of micelles and water-octanol partition coefficients. With these modifications, the model successfully reproduces the binary water-surfactant phase behavior of nine surfactants with good accuracy.