Journal of Molecular Liquids
Aerosols can be modeled for detailed investigations using reverse micelles in the laboratory as well as in computational simulations. A long-standing question in the description of confined water under these conditions is that of a two-state model of core – interface or a three-state model of core – intermediate – interface. In this work, we present results of analysis of water dynamics inside reverse micelles from fully atomistic molecular dynamics simulations. The size and composition of reverse micelles is expressed through w0, the ratio of the number of water molecules to the number of surfactant molecules. Reverse micelles of diverse sizes, with w0 ranging from 5 to 20, were constructed with Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) surfactant and simulated within isooctane solvent. Residence time and diffusion coefficients, in the simulations, both behaved increasingly like bulk water with the increase in size of reverse micelles. Rotational anisotropy autocorrelation was modeled using exponential functions in the short time range of 10–20 ps and longer time data were modeled as a power law fit. Similarly, the diffusion of water in the reverse micelles was also modeled on a power law fit. All these metrics demonstrate a clear progression towards bulk water behavior as the reverse micelle size increases. Additionally, our results also support a 3-layer model of water in a reverse micelle of core – intermediate – interface. These results extend the understanding of water dynamics in reverse micelles and provide further evidence for the 3-layer model.
Crowder, Max; Tahiry, Frozan; Lizarraga, Isabel; Rodriguez, Stephanie; Peña, Nathaly; and Sharma, Arun K., "Computational Analysis of Water Dynamics in AOT Reverse Micelles" (2023). Biology and Chemistry Faculty Publications and Presentations. 12.