Computational predictions of interfacial tension, surface tension, and surfactant adsorption isotherms

Li, Jing; Amador, Carlos; Wilson, Mark R.

Abstract

All-atom (AA) molecular dynamics (MD) simulations are employed to predict interfacial tensions (IFT) and surface tensions (ST) of both ionic and non-ionic surfactants. The general AMBER force field (GAFF) and variants are examined in terms of their performance in predicting accurate IFT/ST, γ, values for chosen water models, together with the hydration free energy, ΔGhyd, and density, ρ, predictions for organic bulk phases. A strong correlation is observed between the quality of ρ and γ predictions. Based on the results, the GAFF-LIPID force field, which provides improved ρ predictions is selected for simulating surfactant tail groups. Good γ predictions are obtained with GAFF/GAFF-LIPID parameters and the TIP3P water model for IFT simulations at a water–triolein interface, and for GAFF/GAFF-LIPID parameters together with the OPC4 water model for ST simulations at a water–vacuum interface. Using a combined molecular dynamics-molecular thermodynamics theory (MD-MTT) framework, a mole fraction of C12E6 molecule of 1.477 × 10−6 (from the experimental critical micelle concentration, CMC) gives a simulated surface excess concentration, ΓMAX, of 76 C12E6 molecules at a 36 nm2 water–vacuum surface (3.5 × 10−10 mol cm−2), which corresponds to a simulated ST of 35 mN m−1. The results compare favourably with an experimental ΓMAX of C12E6 of 3.7 × 10−10 mol cm−2 (80 surfactants for a 36 nm2 surface) and experimental ST of C12E6 of 32 mN m−1 at the CMC.

Citation

Li, J., Amador, C., & Wilson, M. R. (2024). Computational predictions of interfacial tension, surface tension, and surfactant adsorption isotherms. Physical Chemistry Chemical Physics, 26(15), 12107-12120. https://doi.org/10.1039/d3cp06170a

• Journal Article Type: Article
• Acceptance Date: Mar 27, 2024
• Online Publication Date: Mar 27, 2024
• Publication Date: Apr 21, 2024
• Deposit Date: Mar 28, 2024
• Publicly Available Date: Apr 18, 2024
• Journal: Physical Chemistry Chemical Physics
• Print ISSN: 1463-9076
• Electronic ISSN: 1463-9084
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 26
• Issue: 15
• Pages: 12107-12120
• DOI: https://doi.org/10.1039/d3cp06170a
• Public URL: https://durham-repository.worktribe.com/output/2349719