Molecular dynamics simulation of the crystalline short-chain polymer system LiPF6·PEO6(Mw∼ 1000)

In an effort to probe the effect of chain length on the structure and properties of ionically conducting polymer electrolytes, the crystalline system LiPF6·PEO6 has been simulated at 293 K using the Molecular Dynamics Simulation (MDS) technique. The specific system studied is short-chain poly(ethylene oxide) with the formulation CH3–(OCH2CH2)22–OCH3; Mw = 1015, a commercially available mono-disperse short-chain PEO form resembling that studied experimentally (Stoeva et al., J. Am. Chem. Soc., 2003, 125, 4619, ). The methoxy chain-ends have been arranged to reproduce smectic and nematic models. Calculated Li+ ion coordination, polymer chain configuration, chain-end registry and diffraction profiles are compared both with experiment and with the results from earlier MD simulations of infinite PEO chain systems (Brandell et al., J. Mater. Chem., 2005, 15, 1422, ). The differences found are interpreted in the terms of chain-end effects and polymer relaxation.