Poly(ethylene oxide): Electronic Structure, Energetics, and Vibrational Spectrum

Abstract

The electronic structure, energetics, and vibrational spectrum of poly(ethylene oxide) (PEO) are determined from density functional theoretical calculations on model systems (CH2CH2O)nX2, ((EO)nX2), where X is a termination group, such as methyl or hydroxyl, and n varies from 2 to 8. Geometry optimization was performed on these linear model systems chosen to represent the noncrystalline conformer of PEO, and the convergence of selected properties (total energy, vibrational spectra) was studied. To simulate the crystalline conformer, geometry optimization and vibrational spectrum calculations were carried out on a helical (EO)6(CH3)2 model system. Differential scanning calorimetry data were employed to determine the crystalline fraction, used as weight for the simulation of total vibrational spectra, based on the spectra of the two conformers. The high resolution simulated spectra exhibited the contribution of individual vibrational modes to the experimentally observed broad peaks (or envelopes), while the...