Multifunctional PVA–CMC/ZnO–Au Nanocomposite Films with Enhanced UV Shielding, Thermal Stability, and Antibacterial Performance

Abstract

Polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) blend nanocomposites reinforced with plasma-assisted synthesized zinc oxide-gold (ZnO-Au) nanoparticles were prepared via casting at varying nanoparticle concentrations. Structural and interfacial modifications were analyzed using XRD, FTIR, Raman spectroscopy, and XPS. XRD analysis confirmed the nanocomposite crystallinity, showing an average crystallite size of 24.48 nm and a lattice strain of 4.32 × 10^-3 for the 0.15 wt% ZnO-Au composite. FTIR and Raman spectra revealed band shifts and broadening, indicating strong interactions between ZnO-AuNPs and the polymer matrix. XPS analysis further verified Zn and Au incorporation and changes in C 1s and O 1s intensities, reflecting modified surface chemistry. Optical analysis revealed a reduction in the band gap from 4.60 eV (pure PVA/CMC) to 3.52 eV for the 0.15 wt% ZnO-Au nanocomposite, accompanied by an increase in refractive index from 2.058 to 2.244, along with enhanced UV-shielding the performance due to reduced UV transmittance and increased film opacity. Thermogravimetric analysis demonstrated enhanced thermal stability, while antibacterial tests against E. coli and S. aureus confirmed strong antimicrobial activity. These findings demonstrate that PVA/CMC/ZnO-Au nanocomposites are a promising candidate for antibacterial, UV-blocking, food packaging, and optoelectronic applications.