Characterization of amorphous silica nanofiller effect on the structural, morphological, optical, thermal, dielectric and electrical properties of PVA-PVP blend based polymer nanocomposites for their flexible nanodielectric applications

The biodegradable polymers blend matrix of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend (50/50 wt%) dispersed with amorphous silica (SiO2) nanoparticles based polymer nanocomposite (PNC) films (i.e., (PVA-PVP)-x wt% SiO2; x = 0, 1, 3 and 5) were prepared by the aqueous solution-cast method. These PNC films were characterized by employing the X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, differential scanning calorimetry and dielectric relaxation spectroscopy techniques. It is found that the dispersion of nanosize SiO2 particles in the PVA-PVP blend matrix reduces the size of PVA crystallites and, turns the surface morphology from smooth into porous and relatively rough for the PNC films. The SiO2 interaction with polymer structure significantly alters the polymer-polymer interactions, reduces the optical band gap and the glass phase transition temperature, and enhances the melting phase transition temperature of the polymer blend films. The dielectric permittivity of the PNC films initially decreases with the increase of SiO2 contents up to 3 wt%, but at 5 wt% SiO2 concentration it is found nearly same as that of the pristine polymer blend matrix. The ac conductivity of these PNC films increases with the increase of frequency according to the power law relation. The dielectric permittivity exhibits non-linear increase with the increase of temperature of the PNC film whereas its dc conductivity obeys the Arrhenius behaviour. The dielectric and electrical properties of these PNC films realize their suitability as low-permittivity and low loss novel nanodielectrics for the substrate and insulator in the development of various microelectronic and organo-electronic devices.