Stereolithography-printed Bi₂O₃-reinforced photopolymer nanocomposite samples with antibacterial and radiation...

Stereolithography (SLA) is an additive manufacturing technique that allows the production of polymer composite samples with high accuracy and smooth surface quality. This makes SLA suitable for functional surface applications. In this study, photopolymer nanocomposite surfaces reinforced with bismuth oxide (Bi₂O₃) nanoparticles were produced by SLA and evaluated in terms of surface structure, antibacterial activity, electrical properties, electromagnetic shielding, and ionizing radiation shielding performance. Bi₂O₃ nanoparticles were added to a commercial UV-curable photopolymer resin at contents of 1, 3, and 5 wt% and printed layer by layer with a layer thickness of 50 μm. Surface structure and particle distribution were examined by SEM-EDS. The results showed good particle distribution at low Bi₂O₃ contents, while particle accumulation occurred at higher contents due to settling during printing. Antibacterial activity was tested according to ISO 22,196, and all Bi₂O₃-reinforced surfaces showed more than 99% reduction against Escherichia coli and Staphylococcus aureus after 24 h. Surface resistivity measurements performed according to TS EN 1149-1 showed values higher than 10¹² Ω, indicating strong electrical insulation. Electromagnetic shielding effectiveness values remained below 5 dB in the 8-12 GHz frequency range. In addition, ionizing radiation shielding parameters, including mass attenuation coefficient, linear attenuation coefficient, half-value layer, and radiation protection efficiency, were theoretically calculated using WinXCOM and EpiXS. The results showed that increasing Bi₂O₃ content improved photon attenuation, especially at low energies. Overall, Bi2O₃-reinforced SLA nanocomposites provide strong antibacterial performance, electrical insulation, and improved ionizing radiation shielding, making them suitable for multifunctional surface applications.