Long term degradation kinetics and UV shielding efficiency of TiO2 and ZnO coatings on rubber and cork substrates

• TiO 2 and ZnO films were deposited on cork and rubber with varied thicknesses. • TiO 2 band gap ranged from 3.91 eV-4.05 eV, while ZnO ranged from 3.25 eV-3.29 eV. • Severe damage was connected to color changes and reduced FTIR peak intensities. • Degradation kinetics were studied by fitting experimental data to exponential models. • Thicker ZnO films provided better protective performance compared to other coatings. This work investigates the application of transparent oxide coatings to enhance the UV resistance of rubber and cork, and it explores their degradation kinetics under accelerated UV exposure. Thus, TiO 2 and ZnO of varying thicknesses were deposited using magnetron sputtering on both substrates. TiO 2 films were amorphous with dense morphology (thickness: 72 ± 3 nm to 130 ± 3 nm), while ZnO films were polycrystalline with nanocolumnar growth (thickness: 160 ± 4 nm to 580 ± 5 nm). Both films were UV-opaque, visible-transparent, with higher band gap energy for TiO 2 (3.91–4.05 eV) than ZnO (3.25–3.29 eV), decreasing with thickness. Color spectrophotometry and FTIR revealed coating and UV-induced changes, with exponential fittings yielding maximum damage ( Δ C ∞ ) and damage rate (K). Uncoated cork degraded 4–5 times slower than rubbers, while films provided greater protection to rubbers. Δ C ∞ values demonstrated that coatings effective on one rubber worked well on others, with rubbers classified into four categories by UV resistance. Consistently, ZnO-coated samples exhibited the best performance, except for the thinnest ZnO film, whose worse performance was attributed to a UV–Vis shoulder which allowed penetration of radiation of higher energy. TiO 2 films slightly accelerate the degradation kinetics of cork, probably due to some catalytic effect at the interface.