Effects of addition of poly(ethylene glycol) on the formation of anatase nanocrystals in SiO2-TiO2 gel films with hot water treatment

Effects of the addition of poly(ethylene glycol) (PEG) in SiO2-TiO2 gel films on the formation of anatase nanocrystals with hot water treatment were investigated. Anatase nanocrystals were formed in the whole SiO2-TiO2 gel films with the addition of PEG by the! treatment, whereas in the films without PEG the nanocrystals were formed mainly on the surface of the films. PEG in the SiO2-TiO2 films was completely leached out with the hot water treatment in about 1 min. The pores produced by the leaching of PEG probably allow anatase nanocrystals to be formed inside the films. Hydrolysis of Si-O-Ti bonds was presumed to play an important role in the nucleation of anatase nanocrystals in the hot water treatment.