Modification and development of optical, thermal, dielectric properties and antibacterial activity of PVA/SA blend by Ag/Se nanofillers: Nanocomposites for energy storage devices and food packaging applications

Silver nanoparticles (Ag NPs) were synthesized using Capsicum annuum extract, which is a cost-effective and green technique. At the same time, selenium nanoparticles (Se NPs) were prepared by sol-gel technique. Then, a series of PVA/SA blend samples filled with different contents of Ag–Se nanoparticles were prepared via the solution casting way. The nanocomposite films were investigated using different measurements. XRD scans of the nanocomposites displayed a decrease in the crystallinity of the PVA/SA blend with increasing the content of Ag–Se NPs as nanofillers in the PVA/SA matrix. FT-IR spectra indicated the complexation and positive interactions between the PVA/SA blend and Ag–Se NPs. The thermal stability of the polymeric samples was improved after the addition of the nanofiller (Ag–Se NPs), as shown by TGA scans. Moreover, the indirect/direct optical energy gap decreased from 3.96/5.28 to 2.73/3.59 eV with increasing concentrations of Ag–Se NPs, confirming the improvement in the optical properties of the filled polymeric samples, as indicated by UV/visible spectra. Dielectric studies revealed that the filling of Ag–Se NPs increases the defects and leads to a greater number of dipoles within the blend and, thus, an increase in the dielectric constant and dielectric loss of the nanocomposite samples. The antibacterial test showed that all filled samples had broad antibacterial activity against Gram-positive and Gram-negative bacteria compared to pure PVA/SA blend and that it was linearly related to the nanofillers concentrations in the polymeric matrix. Improvements in thermal, optical, and electrical properties make the present nanocomposite samples suitable for multiple functions in many applications, such as high-density energy storage and flexible electronic devices. In contrast, the enhancement in the antibacterial activity could indicate that these nanocomposites can also be used for antibacterial packaging and biomedical purposes.