Connection between thermodynamics and dynamics of simple fluids in pores: impact of fluid-fluid interaction range and fluid-solid interaction strength
William P. Krekelberg, Daniel W. Siderius, Vincent K. Shen, Thomas M. Truskett, Jeffrey R. Errington
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 et al. [Langmuir (29) 14527,(2013)]. Although increasing the fluid-fluid interaction range changes both the thermodynamics and 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 sub-critical temperatures. In this case, the self-diffusivity of the confined and bulk fluids have a nearly identical scaling-relationship with effective density.