Photostability and retention of UV absorber molecules in sol–gel hybrid UV-protective coatings

Highly efficient UV-protecting coatings were prepared, consisting on UV absorber molecules embedded in transparent sol–gel phenyl-functionalized silica thin-films. The photostability and retention of the molecules in the films depend strongly on parameters such as the composition of the hybrid host matrix, the UV-absorber loading in the matrix and the sol–gel preparation conditions. The amount of the modifying phenyl group was found to affect strongly the retention of the UV absorber molecules in the matrix. The retention of the molecules incorporated in the thin-films showed an increase of 21 times as the amount of the phenyl groups is reduced by a factor of 4. On the other hand, the incorporation of increasing amounts of Ph groups lead to a slight decrease of the photostability of the UV absorber molecules. The ability to control the parameters affecting the durability of the UV absorber molecules in the sol–gel matrices allows us increase the effectiveness of the UV-protective films and hence their potential usage in both, indoors and outdoors applications.