In collaboration with Repsol Technology Lab and Imperial College London, researchers from Nextmol have published the paper “Molecular Simulations of Surfactant Adsorption on Iron Oxide from Hydrocarbon Solvents” in the journal Langmuir of the American Chemical Society.

The paper investigates the performance of organic friction modifiers (OFMs) depending on their ability to adsorb onto surfaces and form protective monolayers. Understanding the relationship between OFM concentration in the base oil and the resulting surface coverage is important for improving lubricant formulations. In the paper, we use molecular dynamics (MD) simulations to study the adsorption of three OFMs─stearic acid (SA), glycerol monoostearate (GMS), and glycerol monooleate (GMO)─onto a hematite surface from two hydrocarbon solvents─n-hexadecane and poly(α-olefin) (PAO). We calculate the potential of mean force of the adsorption process using the adaptive biasing force algorithm. We estimate the minimum area occupied by OFM molecules on the surface using annealing MD simulations, and using the MD results, we determine the adsorption isotherms using the molecular thermodynamic theory (MTT). This study demonstrates that MD simulations, alongside MTT, are an accurate and efficient tool to predict adsorption isotherms at solid–liquid interfaces.


Molecular Simulations of Surfactant Adsorption on Iron Oxide from Hydrocarbon Solvents
Pablo Navarro Acero, Stephan Mohr, Marco Bernabei, Carlos Fernández, Beatriz Domínguez, and James P. Ewen
Langmuir, 2021, 37, 50, 14582–14596, DOI: 10.1021/acs.langmuir.1c02133