Polyethylenimine/Graphene Oxide Nanocomposite for Lightweight X-Ray Radiation Shielding in Aerospace Applications.

The demand for lightweight, flexible, and lead-free radiation shielding for next-generation extravehicular activity suits and aerospace habitat liners is rapidly intensifying. This study investigates the structural organization and X-ray attenuation performance (10-60 keV) of polyethylenimine/graphene oxide (PEI/GO) composites with GO loadings up to 50 wt%. Microstructural evolution was systematically tracked via optical image quantification (dispersion, connectivity, and local mixing indices) correlated with micro-Raman spectral mapping. Raman analysis confirmed a structural transition at 40 wt% GO, driven by a dynamic competition between covalent amine-epoxide/carboxyl functionalization and localized π-π stacking of sp2 domains. X-ray transmission and linear attenuation coefficients were evaluated using a dual approach, coupling experimental X-ray exposures with deterministic NIST XCOM calculations and stochastic Monte Carlo simulations. The results demonstrate that GO significantly amplifies low-energy photoelectric absorption due to its oxygen-rich functionalities. An anomalous thickness-dependent attenuation paradox, which can be explained by accounting for forward-scattered Compton buildup in thick blocks and spatial edge refraction along non-percolating cluster interfaces in thin films, was observed experimentally. These findings provide critical material design rules for advanced, flexible, and wearable photon shields operating without mass penalties.