title: Mechanism of diffusion slowdown in confined liquids.
abstract: With the aid of molecular dynamics simulation, we consider why the diffusivity of liquid becomes slower as the liquid is confined to a narrower space. The diffusion coefficient of octamethylcyclotetrasiloxane liquid confined between two mica surfaces was calculated for a range of surface separations from 64 to 23 Å. The resulting separation dependence of the diffusion coefficient can be explained by considering that the molecular diffusion is an activated process. In particular, we find that the increase in the activation energy is closely correlated with the decrease of the potential energy per molecule, from which we propose a molecular-level mechanism of this confined-induced diffusion slowdown.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Tohoku University and JST-CREST, Aoba-yama 6-6-07, Sendai 980-8579, Japan. matsubara@che.tohoku.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Matsubara
authors.forename: Fabio
authors.initials: F
authors.lastname: Pichierri
authors.forename: Kazue
authors.initials: K
authors.lastname: Kurihara