Enhancing optical, structural, thermal, electrical properties, and antibacterial activity in chitosan/polyvinyl alcohol blend with ZnO nanorods: polymer nanocomposites for optoelectronics and food/medical packaging applications

This work presents a comprehensive investigation into the development and characterization of novel nanocomposites composed of chitosan (Cs) and polyvinyl alcohol (PVA) with zinc oxide (ZnO) nanorods (NRs). The study begins with the successful synthesis of ZnO nanorods via the sol–gel technique with an average diameter of approximately 35 nm, as indicated by TEM image and histogram. These ZnO NRs were then seamlessly integrated into Cs/PVA polymer blend-based nanocomposite films through a casting process. The results reveal a series of noteworthy findings, where XRD patterns indicate an increase in intermolecular interactions, leading to softening of the Cs/PVA blend’s polymer chain backbone and disruption of crystalline regions. Complex interactions between ZnO NRs and functional groups within the Cs/PVA matrix are also evident from FTIR analysis, where the spectra show noticeable changes in the intensity and broadness of certain peaks when ZnO NRs concentrations increase. The optical feature are investigated by ultraviolet–visible tecnique (UV–Vis), where the surface plasmon resonance peak of ZnO NRs were observed and the optical energy gap were determined. Furthermore, thermogravimetric analysis (TGA) demonstrates improved thermal stability, owing to blend-NRs interactions that safeguard the structural integrity of Cs/PVA during exposure to elevated temperatures. DC electrical conductivity significantly increases with rising temperature and NRs content. The DC conductivity value of Cs/PVA blend filled with 12 wt% ZnO NRs at 373 K reached 3.39 × 10⁻⁹ S/cm, which increased by more than two orders of magnitude due to increased nanofiller bridging the gaps between localized states, and reducing potential barrier separation and facilitating charge carrier transfer. Furthermore, these nanocomposites exhibit enhanced antibacterial activity, with increased ZnO content correlating with elevated antimicrobial efficacy. These properties make the nanocomposites highly promising for potential in optoelectronic devices where their optical and electrical characteristics can be leveraged. Simultaneously, their demonstrated antibacterial properties make them appealing for applications in food and medical packaging, safeguarding product hygiene and safety.