New observations on the optical properties of PPV/TiO2 nanocomposites

The optical properties of poly(phenylenevinylene) (PPV)/TiO2 nanocomposites, prepared from mixtures of PPV precursor and titanium butoxide ethanol solution in a sol–gel process, are investigated by UV–VIS, FT-IR, PL spectroscopy and TEM. The TEM images showed that the TiO2 nano-aggregates took the form of a sphere and finally ellipsoid with an alignment, as the content of TiO2 increased. FT-IR spectra indicated that the titanium butoxide hydrolyzed to form Ti organic compound, which can result in the alignment structure of TiO2 nanoparticles; at the same time, PPV in TiO2 matrix had the trans-PPV configuration. PL spectra revealed that the light emission of the PPV/TiO2 nanocomposites was from PPV, and the relative intensity of the vibrant components changed with the formation of the TiO2 alignment structure. These phenomena suggest that the TiO2 matrix can form confined environments to control PPV molecular aggregate states and further effect the optical property of PPV.