{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T14:25:54Z","timestamp":1788531954829,"version":"build-2803163510"},"reference-count":35,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T00:00:00Z","timestamp":1788480000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>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\u201360 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\u2013epoxide\/carboxyl functionalization and localized \u03c0\u2013\u03c0 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.<\/jats:p>","DOI":"10.3390\/ma19173762","type":"journal-article","created":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T13:50:44Z","timestamp":1788529844000},"page":"3762","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Polyethylenimine\/Graphene Oxide Nanocomposite for Lightweight X-Ray Radiation Shielding in Aerospace Applications"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9564-4172","authenticated-orcid":false,"given":"Sabina","family":"Botti","sequence":"first","affiliation":[{"name":"Photonics Micro- and Nano-structures Laboratory, Physical Technologies and Security Division, Nuclear Department, ENEA,   Via E. 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