Hierarchically engineered flexible biomass composites for integrated neutron moderation–absorption

Developing flexible materials that reconcile high-efficiency radiation shielding capabilities with superior mechanical properties remains a formidable challenge. Conventional flexible composites face intrinsic limitations, as the high filler loadings required for effective neutron attenuation often precipitate severe strength degradation and poor interfacial compatibility, thereby compromising structural integrity. Herein, we propose a bio-templated strategy utilizing the intrinsic hierarchical collagen fiber network of natural leather (NL) to construct a flexible, integrated material for fast neutron moderation and thermal neutron absorption. The multiscale fibrous architecture and abundant surface functional groups of the collagen matrix enable the uniform incorporation of tungsten (W) nanoparticles and gadolinium (Gd) ions, while interfacial engineering promotes robust coupling with the hydrogen-rich (H) biological scaffold. The resulting ternary W–H–Gd system achieves a cross-energy-domain moderation–absorption synergy, yielding significantly enhanced shielding efficiencies compared with polyethylene (PE) benchmarks, even at moderate functional loadings. Crucially, this hierarchical and interfacial design mitigates the mechanical deterioration typical of highly filled composites, endowing the WGd/NL material with a tensile strength of 10.8 MPa and a softness of 4.9 mm -- both superior to PE. This work establishes a new paradigm for resolving the intrinsic trade-off between protection efficiency and mechanical strength, offering a sustainable route toward flexible, fiber-based shielding materials for extreme radiation environments.