B. Tiss¹, C. Mansilla², D. Martínez^1,3, L. Cunha^1
1Physics Center of Minho and Porto Universities, Braga, Portugal
²CTECHnano Coatings Technologies S.L., Tolosa Hiribidea 76, 20018, San Sebastián, Spain
3Luxembourg Institute of Science and Technology (LIST), Esch-sur-Alzette, Luxembourg
Sunlight's UV radiation is the primary cause of outdoor material aging, particularly affecting cork and rubber. Exposure to UV rays leads to rapid deterioration, resulting in visible discoloration and scratches, especially when combined with mechanical wear. Cork and rubber, both natural substances, are prized for their thermal and acoustic insulating properties, low diffusivity for gases and liquids, and high porosity. They find diverse applications beyond their traditional uses such as wine stoppers, floors, and walls. To address the UV radiation issue and protect these materials, it's logical to apply a protective film without compromising their inherent qualities, thereby shielding them from harsh environmental conditions. However, coating both materials is challenging, but despite these issues, it was possible to deposit TiO₂ and ZnO thin films, using sputtering and ALD. These films have been applied to cork and rubber surfaces with no discernible alteration in color after deposition. To comprehensively assess the aging process of these materials, we employed a combination of analytical techniques. FTIR spectroscopy was employed to analyze molecular changes, while spectrophotometry allowed us to measure color variations. Additionally, we conducted tribological tests to evaluate mechanical wear resistance. Our findings revealed that the coated materials consistently outperformed their uncoated counterparts in terms of UV aging resistance. Furthermore, the coated samples exhibited superior wear resistance compared to their uncoated counterparts. Notably, ZnO thin films demonstrated more effective UV and mechanical protection than TiO₂ thin films. Furthermore, the thickness of the ZnO film had a pronounced impact on the aging of cork and rubber materials, with thicker ZnO films exhibiting enhanced protective performance.