Order-Disorder Transitions and Melting in a Helical Polymer Crystal: Molecular Dynamics Calculations of Poly(Ethylene Oxide)

Structural transitions and the melting behavior of crystalline poly(ethylene oxide),(CH2-CH2-O)n, (PEO) has been investigated using fully atomistic, constant pressure-constant temperature (NPT) molecular dynamics (MD) simulations. Melting of PEO proceeds in two stages; Order parameters reveal the loss of interchain orientational correlations and of chain helicity in the first and second stages of melting respectively. Sliding diffusion and anisotropic reorientational dynamics of the polymer backbone are observed in the solid state, in agreement with 1H NMR experiments.