Effects of diameter and chirality on structural and dynamical behavior of [EMIM][PF6] encapsulated in carbon nanotube: A molecular dynamics study

Molecular dynamics simulations have been performed to investigate the structural and dynamical properties of 1-ethyl-3-methylimidazolium hexafluorophosphate [EMIM][PF6] inside carbon nanotubes (CNTs) at 298 K. Our results indicated that the diameter and chirality of the CNT have significant influences on the structural and dynamical properties of the [EMIM] [PF6]. Our structural results showed significant layering in the mass density profiles of the cations and anions in the radial direction with different intensities in the zigzag and armchair CNTs. The cations close to the pore walls tend to align with their imidazolium ring parallel to the surface. Our dynamics results indicated that the encapsulated cations in ionic liquid move faster than the anions but the dynamics are much slower in the nanotube than in the bulk. The ions have faster dynamics in the armchair nanotube than the zigzag configuration. Our results also showed the more hydrogen bonds formed between cations and anions in the zigzag and smaller CNTs than the armchair and bigger CNTs, respectively.