Structural and dielectric properties of (PEO-PMMA)-SnO2 nanocomposites

Polymer nanocomposite (PNC) films based on poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend as host polymer matrix dispersed with tin dioxide (SnO2) nanoparticles have been prepared by the solution-cast method. X-ray diffraction measurements confirm that these films are semicrystalline and the degree of crystalline phase reduces with increase of SnO2 contents in the polymer blend. The scanning electron microscopy reveals that the surface morphology of the PNC films is smooth with homogeneous distribution of the SnO2 particles. Complex dielectric permittivity, electrical conductivity, electric modulus and impedance spectra of the PNC films have been investigated in the frequency range from 20 Hz to 1 MHz. The real part of the dielectric permittivity of these films has non-linear increase with the increase of SnO2 nanoparticles contents in the PEO-PMMA blend over the audio frequency range, whereas it is found tunable with nanofiller concentration in the range from 2 to 3 at the radio frequencies. Dielectric loss tangent and the loss part of electric modulus spectra exhibit relaxation peaks which are ascribed to cooperative chain segmental dynamics of the PEO and PMMA macromolecules. It is observed that the polymers chain segmental dynamics becomes much faster when only 1 wt% SnO2 nanoparticles are dispersed in the polymer blend matrix, which further enhances moderately with the increase of SnO2 concentration up to 5 wt%. The dielectric relaxation time and electrical conductivity values of the PNC film are found Arrhenius in temperature of activation energies 0.15 eV and 0.43 eV, respectively.