Thin films of polyaniline (PANi) and PANi: titanium oxide (TiO2) composites have been synthesized by sol–gel spin coating technique. The TiO2 powder of particle size 50–60nm was synthesized by the sol–gel technique and the polyaniline was synthesized by the chemical oxidative polymerization of aniline. The composite films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy and the four-probe method. The results were compared with corresponding
data on pure polyaniline films. The intensity of diffraction peaks for PANi:TiO2 composites is lower than that for TiO2. The characteristic FTIR peaks of pure PANi are observed to shift to a higher wavenumber in PANi:TiO2 composite, which is attributed to the interaction of TiO2 particles with PANi molecular chains. The resistivity measurement shows that the molecular chain constitution of polyaniline is the most important carrier in the polyaniline: nano-TiO2 composite