Modulating Aggregation in Microemulsions: The Dispersion by Competitive Interaction Model

29 August 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


A phenomenological model has been developed for the mechanism of action of phase modifiers as additives that control aggregation phenomena within water-in-oil emulsions. Unlike the qualitative “cosolvent” and “cosurfactant” paradigms previously discussed in the literature, the new “Dispersion by Competitive Interaction” model (DCI) explicitly considers the strength and prevalence of different intermolecular interactions that may compete (or act cooperatively) to influence aggregate dispersion and influence phase phenomena within microemulsions. The prior cosolvent and cosurfactant models are considered distinct “regimes” within DCI where either self- or cross-interactions dominate within the landscape of intermolecular interactions. The specific system under consideration, the N,N,N\textsuperscript{$'$},N{$'$}‐tetraoctyl diglycolamide amphiphile extractants with tributyl phosphate or dihexyl octanamide phase modifier additives, represents a new regime – labelled the polar disruption regime – where the phase modifier interactions with the polar micellar core (cross-interactions between different components) are strong enough to disrupt the self-interactions of polar-solute molecules amongst themselves.


phase modifier
solution structure

Supplementary materials

Supplementary Information
Variation of structural entropy of network comprising water and nitric acid, relative change in water cluster distribution with phase modifier, plot of intermittent hydrogen bond lifetime correlation functions, RDF plots for TODGA-DHOA and TODGA-TBP interaction, Tables with calculated relaxation times obtained from the intermittent hydrogen bond lifetime correlation functions for TODGA-water, nitric acid-water and phase modifier-water.


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