Molecular dynamics simulation study of meso-confined propane in TiO2

Abstract

We report the structural and dynamical properties of propane confined in mesoporous TiO2, studied using MD simulations. Results indicate that the propane molecules have a tendency to be adsorbed at the pore walls forming sequential layers. Three different regimes of translational motion can be identified which correspond to motion at different time scales accessible to different experimental probes. The variation of the dynamical behavior with loading differs for different regimes and the trend for one of these is consistent with that obtained in recent neutron scattering experiments on propane in mesoporous TiO2 and silica aerogel. The rotational motion of propane molecules confined in the pore exhibits a very fast free rotation at short times which is followed by isotropic rotational diffusion. This work provides an explanation to the counterintuitive observations of an enhancement in the diffusivity with an increased loading of confined propane in recent neutron scattering experiments.