Dynamics of Poly(butylene oxide) Well above the Glass Transition. A Fully Atomistic Molecular Dynamics Simulation Study

We present fully atomistic molecular dynamics simulations on poly(butylene oxide) (PBO) at a temperature well above the glass transition. The cell is validated by direct comparison of the calculated intermediate incoherent scattering functions of the hydrogens with those obtained from quasielastic neutron scattering (QENS) measurements [ Gerstl C. ; Macromolecules 2012, 45, 7293 ]. The information contained in the simulated atomic trajectories is first used to check the validity and explore the limits of the model used to interpret the QENS results of that work, which extended also to other members of the series of poly(alkylene oxide)s. Furthermore, the details of the segmental dynamics and the localized motions undergone by the side groups are unveiled from the simulations. Full rotations of the pendant groups take place during the decaging of the main-chain segments.