Development of innovative bio-inspired shielding composites based on nanomaterials to mitigate radiological effects...

The widespread use of lead-based occupational radiation protection that is based on toxic and heavy metals has triggered a great emergency in the medical and nuclear industries in terms of ergonomics and the environment. In this paper we have described the effective design of a groundbreaking, lead-free, bio-inspired shielding material that has been designed to counteract mixed-field radiological risks, yet retain the best mechanical ergonomics. With the help of a layer-by-layer vacuum-assisted self-assembly protocol, a sophisticated nacre-inspired "brick-and-mortar" microarchitecture was created. The rigid bricks were graphene oxide (GO) nanosheets densely loaded with silane-functionalized Bismuth Oxide (Bi₂O₃), Tungsten Disulfide (WS₂), and Boron Carbide (B₄C) nanoparticles, and the rigid bricks were intercalculated in a highly flexible thermoplastic polyurethane (TPU) rigid skeleton, the mortar. Experimental evidence showed that such a hierarchical structure fully removed nanoscale agglomeration, allowing a record 60 wt% filler loading without catastrophic embrittlement. The composite (Comp-60) had retained a spectacular 165.7% elongation at the moment of break and better fracture toughness. Comp-60 was radiologically extraordinary at its critical medical diagnostic energy of 59.5 keV with a linear attenuation coefficient of 18.640 cm⁻¹, providing the standard protection of 0.25 mm lead-equivalent, at the thinner thickness of only 0.99 mm, thus compromising garment weight by 40% relative to traditional lead-vinyl aprons. Moreover, when used in nuclear applications, the composite was shown to have very good mixed-field performance absorbing 97.5% of thermal neutrons through Boron-10 (n, [Formula: see text]) capture reaction and effectively attenuating the 478 keV secondary gamma emissions in-situ via the close spatial proximity of high-Z Bi₂O₃ and WS₂ nanoparticles within the layered architecture. Innovative Monte Carlo (MCNP) simulations were entirely consistent with the experimental measurements (error at most < 2%), and experimentally proved the absolute spatial homogeneity of the bio-inspired matrix mathematically. These are non-toxic, lightweight and flexible composite that can be considered as a paradigm shift in production of next generation personal protective equipment to radiation workers.