Dynamics of poly(ethylene oxide) in nanoscale confinements: A computer simulations perspective

Abstract

Molecular Dynamics simulations are used to explore the effect of severe –1 nanometer– confinement on the short-time dynamics of poly(ethylene oxide) (PEO). Bulk and intercalated systems have been atomistically modeled to comparatively illustrate their differences. In particular, we aim to trace the molecular level mechanisms responsible for the counter intuitive distribution of relaxation times recorded by solid state H2 NMR for the C–H bond reorientations in confinements. Computer simulations complement the experiments and reveal that factors such as local density inhomogeneities, proximity of Li+, and disorder in the system, combine to determine the PEO segmental dynamics. In contrast with the respective bulk PEO systems, where a clear transition from distinct solid to liquid like dynamics takes place with increasing temperatures, for the nanoscopically confined chains there persists a coexistence of fast and slow segmental relaxations over the same temperature range.