Hybrid gel composites of melanin and tungsten oxide nanoparticles for enhanced electromagnetic radiation attenuation

Polymer-based composites containing nanostructured tungsten oxide (WO₃) within a Pluronic P123-melanin matrix (PM) were prepared and evaluated for high-energy electromagnetic radiation shielding. Composites containing 5%, 10%, 15%, and 20% WO₃ by weight were structurally and optically characterized. X-ray diffraction (XRD) validated the crystalline structure of WO₃, while scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed uniformly distributed plate-like nanostructures. UV-Vis and photoluminescence (PL) analyses proved significant UV absorption and adjustable emission correlated with increasing WO₃ concentration. Fourier-transform infrared (FTIR) spectroscopy confirmed the chemical stability of the polymer–melanin framework. The addition of WO₃ nanoparticles significantly enhanced the radiation shielding performance, with the 20% WO₃ composite exhibiting the most effective attenuation. Both the linear attenuation coefficient (LAC) and mass attenuation coefficient (MAC) increased with WO₃ concentration, particularly at photon energies below 200 keV. The mean free path (MFP) of WO₃-NPs/PM-5 decreases from 0.275, 6.02, and 7.97 cm to 0.133, 2.85, and 4.13 cm in WO₃-NPs/PM-20 at 31, 662, and 1332 keV, and The half value layer (HVL) of WO₃-NPs/PM-5 decreases from 0.39, 8.69, and 11.05 cm to 0.19, 4.11, and 5.96 cm in WO₃-NPs/PM-20 at 31, 662 and 1332 keV. This reduction across all photon energies is attributed to the increasing concentrations of nanoparticles.