Dielectric and electrical properties of different inorganic nanoparticles dispersed phase separated polymeric nanocomposite bilayer films

Abstract

Phase separated polymer nanocomposite (PNC) bilayer films consisting of poly(vinyl alcohol) (PVA) and poly(methyl methacrylate) (PMMA) matrices (PVA/PMMA = 50/50 wt %) dispersed with 5 wt % amount of inorganic nanoparticles (i.e., Al₂O₃, SiO₂, ZnO and SnO₂) have been prepared by solution-cast method using the polymer blend binary solutions. Complex dielectric permittivity, electric modulus, alternating current (AC) electrical conductivity and impedance spectra of the PNC bilayer films have been investigated in the frequency range from 20 Hz to 1 MHz, at 27°C, by employing the dielectric relaxation spectroscopy. The values of real part of dielectric permittivity of all these films are found less than 2.5, and their dielectric loss part values are significantly low confirming the suitability of these PNC materials as high performance low-permittivity nanodielectrics. The complex dielectric permittivity values of these PNC bilayer films vary with the nanoparticles in the order SnO₂ > ZnO > SiO₂ > Al₂O₃. The complex dielectric permittivity values of Al₂O₃ and SiO₂ dispersed films are found less than 1.33–j0.035 and also remain almost stable over the entire frequency range of measurements. The AC electrical conductivity and impedance values of these films have linear increase and decrease, respectively, with the increase of frequency which confirms their Ohmic behaviour. The direct current (DC) electrical conductivity values of the PNC bilayer films are found of the order of 10^–14 S/cm, and these values have variation of about one order of magnitude with different nanofillers. The dependence of dielectric and electrical properties of the PNC films on the structural and dielectric permittivity of the nanofillers has been explored. The feasibility of these PNC bilayer films as polymer dielectrics, electrical insulator and dielectric substrate in the development of advanced microelectronic devices has been confirmed.