Photodegradation stability of marine coatings derived from PVC binder loaded with composite metal oxides particles

This study aims to investigate the stability against photodegradation of an antifouling marine coating composed of poly(viny chloride) binder mixed with different types of metal oxides particles, including TiO₂, TiO₂ physically mixed with WO₃ and composite metal oxides derived from the coupling of TiO₂ with WO₃ via a sol–gel process (referred to as WO₃@TiO₂). The stability test was conducted using an accelerated weathering test, and changes in chemical structure, morphology, and thermomechanical properties of the coating were determined using FTIR, SEM-EDX, TGA, and tensile testing techniques, respectively. Discoloration of PVC, accompanied by deterioration and the formation of cavities on the coating surface, was observed when the binder was loaded with TiO₂. These phenomena were attributed to the dehydrochlorination and photooxidative degradation of PVC, accelerated by the radical species generated from the photocatalytic reaction of TiO₂. However, these features disappeared when WO₃@TiO₂ particles were used as a replacement for TiO₂. The discrepancies were discussed in the context of the capability of WO₃ to act as an electron storage substance, thereby suppressing the photooxidative degradation of PVC.