Nucleation and growth of TiO2 thin films on modified polystyrene surfaces

Partially crystalline TiO2 was deposited on polystyrene substrates by liquid phase deposition. Both nucleation and adhesion depend on the respective pretreatment of the polymer. Coherent films are formed on untreated substrates and surfaces hydroxylated by aqueous sodium peroxodisulfate solution, but satisfactory film adhesion is only observed on the modified surface. The formation of continuous films is not observed on polystyrene etched by H2SO4/SO3 where material deposition was only initiated at few nucleation sites. The TiO2 precipitation was characterized as a function of time and compared to previous results on wet chemically grafted PS. A film formation mechanism is proposed which can account for the textured constitution of TiO2 observed by X-ray diffraction experiments.