Influence of green synthesized gold nanoparticles on the structural, optical, electrical and dielectric properties of (PVP/SA) blend

Abstract

Green synthesized gold nanoparticles with size 8–27 nm have been added to Polyvinyl pyrrolidone/Sodium alginate (PVP/SA) (50/50 wt%) blend by the casting technique. X-ray diffraction exposed the amorphous nature of the polymer blend (PVP/SA) and filled samples. The amorphous region increases with increasing Au NPs content. Fourier transform infrared spectra were achieved to illustrate the change in structure of the samples according to the filling manner. Ultraviolet/visible analysis was used to study the effect of adding Au NPs on the optical properties and used to calculate the energy gap (Eg) of (PVP/SA) composites. The values of optical energy gap (Eg) are reduced from 5.18 eV for blend to 3.52 for the nanocomposite film in the direct transition. Upon the addition of Au NPs, An enhancement for the conductivity, dielectric permittivity (ε′) and dielectric loss (ɛ") of (PVP/SA) are detected. The value of the activation energy (Ea) of the dielectric relaxation is calculated and is found to be 0.18 eV. Morphological properties were studied using scanning electron microscopy. SEM revealed the partial compatibility between the polymer blend (PVP/SA) and the Au NPs. Transmission electron microscopy image exhibited the cubic shape for gold nanoparticles with an average size 10–15 nm. Finally, Nano composites films can be used in several applications such as optical and optoelectronic devices.