Comparison of the effect of free volume fraction on the dielectric properties of polyethylene oxide bulk and thin film

Abstract

Thin film polyethylene oxide has been produced by the thermal evaporation technique. The dielectric properties and molecular dynamics of bulk and thin film polyethylene oxide have been studied in the frequency range 0,1-Hz 20 MHz and temperature range 213–333 K by broadband dielectric spectroscopy to investigate the effect of structural differences. Primary (α- relaxation) and secondary (β, γ- relaxation) relaxation processes have been analyzed for bulk and thin film polyethylene oxide. The activation energies of β-relaxation for bulk and thin film were calculated as 2,52 eV and 0,78 eV, respectively. The motion of entire polymer chains, namely, the normal mode, has been determined for both bulk and thin film polyethylene oxide samples. The glass transition temperature and the relaxation behavior have been modeled by Vogel–Fulcher–Tamman and Cole–Cole equations, respectively. The free volume fraction, which is attributed to the reason for the difference between Vogel temperature and glass transition temperature, was calculated using the Dolittle equation. It is detected that the dielectric constant of polyethylene oxide thin film is 10 times greater than polyethylene oxide bulk. There is consistency among dielectric constants, activation energies, and free volume fractions for bulk and thin film samples. It is observed that polyethylene oxide thin film is more brittle than polyethylene oxide bulk sample. It has been reported that the thin-film polyethylene oxide with a high dielectric constant can be nominated as a candidate for production in biocompatible, organic coverages and supercapacitors.