Structure–dynamic properties relationships in poly(ethylene oxide)/silicon dioxide nanocomposites: dielectric relaxation study

Films of polyethylene oxide (PEO) filled with silicon dioxide (SiO 2 ) were synthesized via casting method. The formation of the PEO/SiO 2 nanocomposites was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) measurements. The XRD patterns confirmed that increasing SiO 2 in semicrystalline PEO enhances the amorphousity and causes a disturbance in the crystalline phase. The influence of the SiO 2 on the dielectric relaxation spectra of PEO in wide temperature and frequency ranges was investigated. Two molecular relaxation processes are observed: main ( α -) and secondary ( β -) relaxations. For the α -process, the process slowed down with adding SiO 2 fillers reflecting an increase in the glass transition temperature, T g . This trend was also verified by differential scanning calorimetry (DSC). The findings indicated that adding SiO 2 restricted the motion of PEO segments, while such changes were not observed in the glassy state. Further, the attenuation of the electric field of the terahertz waves passed through PEO/SiO 2 samples was evaluated. In the terahertz range, the resonant peaks of PEO originated from lattice vibration feature the complex dielectric function. These peaks were weakened broadened and red-shifted by increasing of SiO 2 concentrations.