Designing Polymer Nanocomposites for X‐Ray Shielding: Mechanisms, Architectures, and Scalable Processing

The expanding use of X‐ray technologies in healthcare, aerospace, security, and manufacturing has intensified demand for shielding materials that deliver high attenuation efficiency with low density, flexibility, and environmental safety. Although lead remains effective, its toxicity and rigidity drive the search for lightweight, lead‐free alternatives. Polymer nanocomposites incorporating high‐atomic‐number fillers have emerged as promising candidates for next‐generation radiation protection. This review critically assesses recent advances in polymer‐based nanocomposites for diagnostic X‐ray shielding, establishing structure‐mechanism‐performance relationships that connect photon‐matter interactions with filler chemistry, particle size, dispersion, and composite architecture. The relative contributions of photoelectric absorption and Compton scattering are analyzed to guide materials design across relevant energy ranges. Single‐filler systems (e.g., Bi 2 O 3 , WO 3 , Gd 2 O 3 ) are compared with multi‐filler strategies exploiting complementary K‐absorption edges to reduce energy‐dependent attenuation gaps. Fabrication routes, including solution casting, electrospinning, melt processing, coatings, leather doping, and additive manufacturing, are evaluated in terms of microstructural control, mechanical compliance, and scalability. Emerging bio‐inspired and hierarchical architectures, such as nanofibrous membranes and ultralight aerogels, illustrate how structural engineering enhances attenuation while preserving flexibility. Key challenges and future directions toward predictive modeling and sustainable manufacturing are outlined.