Connection Between Thermodynamics and Dynamics of Simple Fluids in Pores: Impact of Fluid–Fluid Interaction Range and Fluid–Solid Interaction Strength

5 years ago

Connection Between Thermodynamics and Dynamics of Simple Fluids in Pores: Impact of Fluid–Fluid Interaction Range and Fluid–Solid Interaction Strength

Jeffrey R. Errington, Vincent K. Shen, Daniel W. Siderius, Thomas M. Truskett, William P. Krekelberg

Using molecular simulations, we investigate how the range of fluid–fluid (adsorbate–adsorbate) interactions and the strength of fluid–solid (adsorbate–adsorbent) interactions impact the strong connection between distinct adsorptive regimes and distinct self-diffusivity regimes reported in [Krekelberg, W. P.; Siderius, D. W.; Shen, V. K.; Truskett, T. M.; Errington, J. R. Langmuir 2013, 29, 14527−14535]. Although increasing the fluid–fluid interaction range changes both the thermodynamics and the dynamic properties of adsorbed fluids, the previously reported connection between adsorptive filling regimes and self-diffusivity regimes remains. Increasing the fluid–fluid interaction range leads to enhanced layering and decreased self-diffusivity in the multilayer-formation regime but has little effect on the properties within film-formation and pore-filling regimes. We also find that weakly attractive adsorbents, which do not display distinct multilayer formation, are hard-sphere-like at super- and subcritical temperatures. In this case, the self-diffusivity of the confined and bulk fluids has a nearly identical scaling relationship with effective density.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b04232

DOI: 10.1021/acs.jpcc.7b04232