HR MAS NMR, dielectric impedance and XRD characterization of polyethylene oxide films for structural phase transitions

The amorphous/crystalline phase transition behavior of PEO films prepared by spin casting method was studied. According to X-ray diffraction (DELTA) analysis, PEO film has a semicrystalline nature at room temperature. The amorphous to crystalline nature of PEO increases with temperature until reaching an amorphous state at 333 K. 1H NMR spectra of PEO in the temperatures between 298 K and 323 K exhibit two main peaks at around 1.132 ppm and 3.174 ppm with very different widths, where the narrow component can be assigned to the mobile polymer chains in the amorphous phase, whereas the broad component is assigned to the more rigid molecules in the crystalline phase. The calculated activation energies from the Arrhenius fit of the Gamma(1) data of the crystalline and amorphous phases are comparable and found to be 0.252 eV and 0.221 eV, respectively. Form fitting dielectric loss (epsilon '') and the electrical modulus (M '') data with the Havriliak-Negami model with addition of the electrical conductivity term in the case of epsilon '', it was deduced that the inverse relaxation time (tau(-1)), dielectric strength (Delta epsilon) and electrical conductivity (sigma) follow an Arrhenius-like behavior plot versus reciprocal temperature.

Automated summary

The amorphous/crystalline phase transition behavior of PEO films prepared by spin casting method was studied. The PEO film shows semicrystalline nature at room temperature and becomes amorphous at 333 K. 1H NMR spectra analysis reveals two main peaks corresponding to mobile polymer chains in the amorphous phase and more rigid molecules in the crystalline phase. The calculated activation energies for crystalline and amorphous phases are comparable.