Local dynamics of poly(ethylene oxide) confined in 1 nm slits

Molecular Dynamics simulations are used to explore the short-time dynamics of nanoscopically confined poly(ethylene oxide). Both bulk and confined systems have been studied using an atomistically detailed force field so as to comparatively illustrate their differences and complement experimental results. Our aim is to elucidate the origins of the counter intuitive distribution of relaxation times for C-H bond reorientation for PEO in severe confinements, as experimentally observed in solid state ²H NMR studies. In contrast with the respective bulk PEO system, where a transition from distinct solid to liquid like dynamics is seen with increasing temperature, for the confined chains there is a coexistence of fast and slow segmental dynamics over a wide temperature range. Our studies have revealed that factors such as local density inhomogeneities, proximity of Li⁺, and translational motion, synergistically contribute to the generation of fast PEO segmental dynamics in 1nm confinements.