Effect of ZnO/MWCNT incorporation on the multifunctional properties of chitosan–PEO nanocomposites for potential food-packaging applications

This study investigates the effect of zinc oxide nanoparticles (ZnO) and multi-walled carbon nanotubes (MWCNTs) on the structural, optical, dielectric, mechanical, and antibacterial properties of chitosan/polyethylene oxide (Cs/PEO) polymer blends. Nanocomposite films with ZnO/MWCNT loadings ranging from 1 to 6 wt% were fabricated using the solution-casting method. X-ray diffraction and Fourier-transform infrared spectroscopy confirmed successful blending and the presence of interfacial interactions between the polymer matrix and the incorporated fillers. Optical analysis showed a gradual reduction in the optical band gap with increasing filler content, where the direct band gap decreased from 4.77 eV for pristine Cs/PEO to 3.63 eV at 6 wt%, while the indirect band gap reached 1.54 eV. Dielectric measurements revealed enhanced dielectric permittivity and AC conductivity with increasing filler concentration, consistent with Jonscher's power-law behavior. Mechanical testing indicated an improvement in tensile strength, reaching a maximum value of 25 MPa at 4 wt% ZnO/MWCNT loading compared to 19 MPa for the unfilled blend. The nanocomposite films also exhibited antibacterial activity against S. aureus and E. coli, with inhibition zones increasing with filler content. Although the results demonstrate improved multifunctional properties within the investigated composition range, the study is limited to laboratory-scale characterization, and further investigations addressing long-term stability, biodegradation behavior, and food-contact safety are required before practical food-packaging applications can be fully assessed.