A gas-templated CeO2 nanoparticle coating with tailored defects for enhanced UV durability of PET films

Abstract

Polyethylene terephthalate (PET) suffers from photo-oxidative degradation under prolonged ultraviolet (UV) exposure, limiting its service life in packaging and outdoor applications. Although CeO₂ nanoparticles (CeO₂ NPs) offer efficient UV absorption, conventional synthesis methods yield severely agglomerated particles with poor dispersion, compromising both shielding efficiency and optical transparency. Herein, we report a gas-templating strategy to synthesize well-dispersed CeO₂ NPs with a uniform size (∼10.8 nm) and a high specific surface area (109.2 m² g⁻¹). Spectroscopic analyses reveal that CeO₂ NPs possess a narrower optical bandgap, a higher Ce³⁺/Ce⁴⁺ ratio, and a higher concentration of surface oxygen vacancies than conventionally prepared bulk CeO₂, collectively enhancing UV absorption. When incorporated into a UV-curable coating on PET films, the CeO₂ NPs coating achieves a broad UV cutoff approaching approximately 360 nm while maintaining high visible transparency (∼86%). The coated film exhibits excellent UV durability with negligible transmittance change after 100 h of continuous irradiation and enhanced scratch resistance. This work establishes a facile strategy for high-performance UV-blocking coatings, extending PET durability in demanding applications.