Exploring the impact of silver nanoparticles on the structure, optical properties, and dielectric response of PVA–PVP blends

Silver nanoparticles (AgNPs) were chemically synthesized and incorporated into a polyvinyl alcohol–polyvinylpyrrolidone (PVA–PVP) polymer blend using a solution casting method to create PVA–PVP/AgNPs nanocomposite films. Transmission electron microscopy (TEM) revealed uniformly dispersed spherical AgNPs with diameters ranging from 10 to 30 nm, which strongly depend on precursor concentration. X-ray diffraction (XRD) confirmed the semi-crystalline structure of the (PVA–PVP) blend, while Fourier Transform Infrared (FTIR) indicated specific interactions between the silver species and the (PVA–PVP) matrices. UV–Vis spectroscopy showed a surface plasmon resonance (SPR) band between 380 and 400 nm, confirming the successful incorporation of nanoparticles. The position and width of this band correlated with particle size and dispersion. The optical band gap, estimated from Tauc plots, decreased from 5.28 eV for the pure PVA–PVP matrix to 5.18 eV upon AgNPs addition, suggesting improved electronic transition characteristics. Broadband dielectric spectroscopy (0.1 Hz–20 MHz) indicated enhanced dielectric constant and loss at low-frequency attributable to interfacial and space-charge polarization effects. PVA–PVP/AgNPs interfaces introduced varying properties, while the conductivity spectra revealed frequency-dependent hopping processes.