Enhanced Radiation Shielding with Conformal Light-Weight Nanoparticle-Polymer Composite.

This article reports a new property enabled by nanoparticles, where bismuth nanoparticles added in a polymer matrix can block X-ray radiation several times more efficient than microparticles at the same mass ratio. Bismuth nanoparticles are made with cellulose nanofibers and dispersed evenly into a polymer. A four time reduction in the mass of bismuth material is identified at 2% mass ratio when nanoparticles (5 nm in diameter) are used in composite to shield a given flux and energy of radiation, in relative to those of microparticles (5 μm diameter). The enhancement in radiation shielding is primarily attributed to close packing of nanoparticles normal to incoming X-ray direction, which is enabled by strong affinity of nanoparticles to interstitial space of cellulose nanofibers and even distribution of nanoparticles inside polymer. Given its low cost, light weight, and structure conformability, bismuth nanoparticle-polymer composite will find its use in a wide range of fields related to personal radiation protection.