Surface electrostatic potential Ψ is a key characteristic of colloid particles. Since the surface of the particles adsorbs various compounds and facilitates chemical reactions between them, Ψ largely affects the properties of adsorbed reactants and governs the flow of chemical reactions occurring between them. One of the most popular methods for estimating Ψ in hydrophilic colloids, such as micellar surfactant solutions and related systems, is the application of molecular probes, predominantly acid–base indicator dyes. The Ψ value is calculated from the difference of the probe’s indices of the apparent acidity constant between the examined colloid solution and, usually, some other colloid solution with noncharged particles. Here, we show how to implement this method in silico using alchemical free energy calculations within the framework of molecular dynamics simulations. The proposed implementation is tested on surfactant micelles and is shown to predict experimental Ψ values with quantitative accuracy depending on the kind of surfactant. The sources of errors in the method are discussed, and recommendations for its application are given.
Bibliographical noteThis document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry B, copyright © 2023 American Chemical Society, after peer review and technical editing by the publisher. To access the final edited and published work see: https://doi.org/10.1021/acs.jpcb.2c07012.
Funding & Acknowledgements: V. F. thanks the Ministry of Education and Science of Ukraine for financial support in the frame of the project #0120U101064. V. F. and D. N. acknowledge the use of HPC Midlands supercomputer funded by EPSRC, grant number EP/P020232/1; the access to HPC Call Spring 2021, EPSRC Tier-2 Cirrus Service; the access to Sulis Tier 2 HPC platform hosted by the Scientific Computing Research Technology Platform at the University of Warwick. Sulis is funded by EPSRC Grant EP/T022108/1 and the HPC Midlands+ consortium. N. M.-P. thanks the Ministry of Education and Science of Ukraine for financial support in the frame of the project #0122U001485.
- Materials Chemistry
- Surfaces, Coatings and Films
- Physical and Theoretical Chemistry