Improving the functional properties of chitosan/carboxymethyl cellulose biopolymer blend by incorporating zinc oxide/aluminium oxide nanofillers for advanced energy storage and optoelectronic applications.

This study investigates the synergistic effects of zinc oxide (ZnO) nanorods and aluminium oxide (Al₂O₃) nanoparticles on the functional properties of chitosan/carboxymethyl cellulose (Cs/CMC) biopolymer blends. Cs/CMC/ZnO-Al₂O₃ nanocomposite samples were prepared using the solution casting method. SEM analysis revealed the nanoscale dispersion of ZnO nanorods and Al₂O₃ nanoparticles within the Cs/CMC matrix, while XRD spectra confirmed the crystalline nature of the nanofillers and their impact on reducing the crystallinity of the polymeric nanocomposites. FTIR spectra indicated strong interactions between ZnO-Al₂O₃ nanofillers and Cs/CMC blend. The incorporation of ZnO-Al₂O₃ significantly tuned the optical absorption and reduced the indirect and direct band gaps from 2.91 and 4.16 eV (pure Cs/CMC matrix) to 1.20 and 2.41 eV (nanocomposite with the highest filler loading). Dielectric analysis showed a maximum dielectric constant for the 2.0 wt% ZnO-Al₂O₃ composite, while Nyquist plots indicated improved bulk conductivity and double-layer capacitance formation. Mechanical analysis further revealed an increase in tensile strength with the addition of nanofillers. These experimental findings demonstrated that the ZnO-Al₂O₃ combination synergistically enhanced the physicochemical properties of the Cs/CMC blend, highlighting the potential of these nanocomposites for flexible dielectric capacitors and optoelectronic applications.