Photostabilization of cationic UV-cured coatings in the presence of nanoTiO₂

The effect of TiO₂ nanoparticles for sun-weathering protection of UV-cured coatings is investigated. TiO₂ is either introduced in the form of nanoparticles in the photocurable formulations or generated in situ via sol-gel process. Cured films containing comparable amounts of TiO₂ were weathered for 800 h under UV irradiation and compared with free-TiO₂ coating. The TiO₂ presence induces a clear lower mass loss decrease during weathering as well as a lower gel content decrease. The TiO₂ screen effect is also confirmed by a lower alkyl-band reduction monitored by FT-IR during weathering. The TiO₂ generated in situ via sol-gel gives rise to transparent coatings without interfering with photopolymerization process and therefore without compromising UV-cured film properties.