Tunable Nanoeffect of ZnO on the Properties of Poly(hydroxybutyrate) Membranes

Polymeric membranes composed of poly-(3-hydroxybutyrate) (PHB) integrated with zinc oxide nanoparticles (ZnO NPs) or quantum dots (ZnO QDs) were successfully prepared by using a sol-gel method for nanostructure dispersion. The resulting PHB/ZnO membranes exhibited uniform morphology and fluorescence with well-dispersed nanostructures confirmed by UV-vis spectrophotometry, fluorescence analysis, and FTIR spectroscopy. Spectral analysis revealed that ZnO NPs and QDs enhanced UV-blocking capabilities and reduced the level of membrane yellowing. Physicochemical evaluations showed that the fluorescence remained stable under prolonged water vapor exposure. Increasing the ZnO content (5, 10, and 15%) led to higher membrane density, wettability, and hardness. Swelling and water vapor permeability (WVP) tests indicated that ZnO QDs were the most effective in reducing moisture diffusion, suggesting the formation of internal barriers. Despite increased surface hydrophilicity, WVP decreased, highlighting the dual functionality of the nanostructures. Antibacterial assays demonstrated inhibition of <i>Staphylococcus aureus</i> growth by up to 30.08% (ZnO NPs) and 21.83% (ZnO QDs). These findings support the potential of PHB/ZnO membranes as multifunctional materials for advanced packaging applications, offering tailored UV protection, moisture control, and antimicrobial properties suitable for the food, pharmaceutical, and cosmetic industries.