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.