Water-based X/γ-ray shielding coating: design of core-shell structure and waterborne matrix, and its radiation attenuation properties

To address the toxicity, weight, and environmental limitations of lead-based radiation shields, this research develops a lightweight water-based radiation attenuation coating via facile integration of core-shell structured Gd@Si and Bi@Si fillers into a waterborne polyurethane/polyvinyl alcohol matrix. The tetraethyl orthosilicate-modified core-shell design enables uniform dispersion of high atomic number fillers (up to 70 wt%) while enhancing interfacial photon scattering. At 1.5 mm thickness, this coating achieves 99.1 % X-ray attenuation efficiency at 31 keV, which is comparable to 0.25 mm lead, and a γ-ray mass attenuation coefficient of 0.1408 cm 2 /g at 662 keV, exceeding lead by 44 %. Simultaneously, the composite maintains robust mechanical properties (683.9 % elongation at 50 wt% loading) and thermal stability (264.9 °C onset decomposition temperature). With a density 78 % lower than lead, inherent hydrophobicity (97.5° contact angle), and adhesion to diverse substrates, this sprayable coating offers a scalable, eco-friendly solution for radiation protection in medical, nuclear, and aerospace applications.