One-Pot Mechanochemical Dual-Functionalization of Bi Powder: Constructing High-Loading Flake Bi@PDMS Composites for...

To address the limitations of traditional lead shielding (toxicity, weight) and unmodified bismuth fillers (poor dispersion), this study develops an improved "one-pot" ball milling method. This one-pot strategy effectively achieves in-situ silane (vinyltrimethoxysilane, A171) modification and transforms bismuth powder into a flake-like morphology. Here, A171 bonds covalently to the bismuth surface via Si─O─Bi linkages, thereby converting bismuth from hydrophilic to hydrophobic. This dual functionalization enables uniform dispersion of Bi in polydimethylsiloxane (PDMS) at a high filler loading of 70 wt% while retaining excellent mechanical flexibility (tensile strength 0.42 MPa, elongation 166%), thermal stability (30 °C higher than that of pure PDMS), and fatigue resistance. The flake-like modified Bi (M-Bi) forms a 3D shielding network that extends X-ray propagation paths. The resulting 0.2 cm-thick 70M-Bi@PDMS composite exhibits 92% X-ray shielding efficiency for 60 keV X-rays, with corresponding linear (μ) and mass (µm) attenuation coefficients of 13.30 cm^-1 and 3.50 cm² g^-1, respectively, and 75% shielding efficiency at 80 keV. In terms of radiation shielding performance, it outperforms commercial lead shielding materials. This work provides a potentially scalable method for developing lead-free, lightweight, and flexible X-ray shielding materials for wearable applications.