Visibly transparent ammonium borate/PDMS films for efficient neutron shielding applications

Abstract

Visibly transparent materials with neutron-shielding capability are highly desirable for emerging applications in aerospace, personal protection, and compact nuclear systems. However, conventional boron-based shielding composites often compromise optical clarity due to the presence of large filler particles and poor dispersion. In this study, we report transparent polydimethylsiloxane (PDMS) composite film incorporating hydrothermally synthesized ammonium borate (AB) nanoparticles as neutron-shielding fillers. The synthesized AB nanoparticles (∼27 nm) exhibited dramatically smaller size and better dispersion compared to commercial AB powders (∼7 μm), enabling the composite films to maintain high visible light transmittance and low optical haze at equivalent filler loading. At a filler loading of 100 mg per 2 g of PDMS, the AB-PDMS film achieved a linear neutron attenuation coefficient μ = ∼0.51 mm−1 while preserving ∼86.3 % total transmittance at 550 nm, in contrast to a comparable film with commercial borate, which showed only ∼66.1 % transmittance for a similar μ. These results demonstrate that minimizing filler particle size and dispersion quality is key to balancing neutron shielding efficiency and optical clarity. With further optimization, such borate-based nanoparticle composites present a promising route toward multifunctional radiation shielding that retains visual transparency.