How wall curvature affects the structure of fluid around a cylindrical nanoparticle: a DFT approach.

In this work, the perturbative fundamental measure theory has been employed to obtain the two-dimensional density distributions of the two hard-sphere and hard-core Two-Yukawa fluids around a hard cylindrical nanoparticle. We have performed our calculations for different densities and temperatures. It has been observed that the oscillatory behavior of structure of molecules around a cylindrical nanoparticle increases with density and with decreasing wall curvature. In fact, energy and entropy effects determine fluid structure around the cylindrical nanoparticle. Our results show that, in the absence of any long-range wall-molecule and molecule-molecule interactions, hard-sphere-hard-wall, the effect of wall curvature on structure is determined by entropy effects. In this case, molecules show a reduced tendency to accumulate at the wall with increasing curvature and a minimal tendency to position themselves at the nanoparticle edges. Energy effects in fluids with molecule-molecule attractions, Yukawa fluids, may lead to an increase in the tendency of their molecules to accumulate at more curved walls. In these systems, the competition between energy and entropy effects may reverse their molecular behavior such that they have the greatest tendency to accumulate at the edges rather than at other regions. Cases have been observed in which the domination of energy effects causes the depletion phenomenon near the walls. In this study, these observations have been confirmed by studying the local excess adsorptions around different regions of a cylindrical nanoparticle.