Dielectric and optical properties of alumina and silica nanoparticles dispersed poly(methyl methacrylate) matrix-based nanocomposites for advanced polymer technologies

Dielectric behaviour of the polymer nanocomposite (PNC) films comprise alumina (Al2O3) and silica (SiO2) nanoparticles (1, 3, and 5 wt%) dispersed in poly(methyl methacrylate) (PMMA) matrix was investigated in the frequency span of 20 Hz to 1 MHz at 30 °C and also with temperature variation (30–60 °C) for the 3 wt% nanofillers containing PNC films. Some changes in the dielectric permittivity and electrical conductivity were observed with the increase of nanofiller content, frequency variation, and rise in temperature of these films. Electric modulus spectra confirmed a broad relaxation peak at the lower frequencies for the Al2O3 loaded PNC films which attribute to the PMMA bulky side ester groups rotation, whereas this relaxation was not observed for the SiO2 filled PNC films in the same experimental frequency range. The UV–Vis absorbance, transmittance, and reflectance spectra of these PNCs showed a gradual variation with the increase of Al2O3 and SiO2 contents in the films. The energy bandgap decreases, whereas the Urbach energy, refractive indices, and optical conductivity enhance with the increase of filler concentration in these composites. The X-ray diffraction (XRD) study revealed the predominantly amorphous nature of these materials and the homogeneity of the hybrid was evidenced by their SEM images. The energy dispersive X-Ray (EDX) mapping revealed the purity of these hybrid composites. The results demonstrated that these PNC films are low permittivity polymeric nanodielectrics (PNDs), and their controllable optical parameters with the filler contents could be technologically important in the design and development of some advanced microelectronic and optoelectronic devices.