Preparation of titania/PDMS hybrid films and the conversion to porous materials

Transparent films of titania/poly(dimethylsiloxane) (PDMS) hybrids were prepared by the solvent evaporation from the precursor solution prepared by the co-hydrolysis and co-condensation of titanium tetraisopropoxide and a methoxy-functionalized PDMS. The hybrid films were flexible and had high homogeneity of the composition. The organic groups of PDMS were decomposed at 400 degrees C in air to form porous films. Though the heated films were rather brittle compared to the as-synthesized films, they were still transparent and homogeneous. The BET surface areas of the films after the heat treatment at 400 degrees C were over 300 m(2)/g, while the as-synthesized hybrid films were non porous. According to the BDDT classification, the nitrogen adsorption/desorption isotherms of the calcined films were Type 1, showing that the films were microporous. The titania domains were still amorphous after the heat treatment at 400 degrees C and transformed to anatase after the heat treatment at 1,000 degrees C.