UV-C radiation has emerged as a germicidal agent against pathogens, particularly following the COVID-19 pandemic. While UV-C effectively reduces cross-contamination in hospitals, it induces photodegradation in polymer devices, potentially damaging and posing risks to patient safety. Therefore, it is crucial to detect the effects of UV-C photodegradation on early stages, as well as the effects of prolonged UV-C exposure. In this study, we investigated the UV-C photodegradation (254 nm, 471 kJ/mol) of isotactic polypropylene homopolymer (PP), commonly used in medication packaging. The impact of UV-C on PP was evaluated through rheology and infrared spectroscopy. Surface energy was measured by the contact angles formed by drops of water and diiodomethane. The effects of photodegradation on the polymer’s morphology were examined using scanning electron microscopy, and the melting temperature and crystallinity by differential scanning calorimetry. Lastly, the effect of UV-C on molecular mobility was studied using ¹H Time Domain Nuclear Magnetic Resonance (¹H TD-NMR). These techniques proved to be valuable tools for identifying the early stages of UV-C photodegradation, and ¹H TD-NMR was a sensitive method to identify the chain branching as a photodegradation product. This study highlights the impact of UV-C on PP photodegradation and hence the importance of understanding UV-C-induced degradation.

Its properties and biocompatibility make poly(ether sulfone) (PESU) one of the ultimate choices for medical devices. However, despite its desirable properties, PESU is sensitive to UV radiation, which compromises its application and patient safety following hospitals' disinfection protocols. These procedures may vary depending on the facility, running in cycles or until the UV-C dosage reaches a set value. Due to the lack of standardized procedures followed by healthcare institutions and the limited number of studies investigating the effects of cyclic UV exposure, this study aims to answer the following question: Does UV-C photodegradation affect polymeric devices differently depending on the exposure mode? To address this question, PESU was exposed continuously and in cycles under UV-C irradiation, and the differences between these modes were evaluated by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), the contact angle using water, tensile strain, and rheology. FTIR and XPS showed that UV-C photodegradation in both exposure modes favors hydroxyl formation. The Cole-Cole plot from the rheological measurements indicated that cyclic exposure affects the polymer molar mass distribution more than continuous exposure. Tensile tests highlighted PESU’s UV sensitivity, severely reducing elongation at break after only 1 hour of exposure. Finally, SEM images revealed distinct effects of the UV-C exposure modes on the PESU surface: cracks and holes formed under continuous exposure, whereas cyclic exposure showed a rod-like morphology, possibly due to additive blooming.