MD Simulations and experimental study of structure, dynamics, and thermodynamics of poly(ethylene oxide) and its oligomers

Molecular dynamics (MD) simulations have been performed on poly(ethylene oxide) (PEO) and its oligomers, using quantum chemistry-based force fields with and without many-body polarizable interactions. Inclusion of the many-body polarization in the model resulted in increased populations of the tgt and tgg conformations of 1,2-dimethoxyethane and slightly slower dynamics. Increasing the PEO dipole moment also led to increased populations of the tgt and ttg conformers and slower dynamics. Quasi-elastic neutron scattering, dielectric relaxation, and C-13 spin-lattice relaxation experiments have been performed on PEO and its oligomers. New C-13 NMR experiments yielded spin-lattice relaxation times that were similar to2-3 times larger than those in the previous experiments, which is in good agreement with the current simulation results. Good agreement between the MD simulation results using many-body polarizable and two-body nonpolarizable potentials was found with experiments for thermodynamic, transport, structural, and dynamic properties.