Synthesis and humidity sensing characteristics of polyaniline/BaTiO3 composites.

An attempt has been made towards the synthesis of polyaniline/BaTiO3 (PANI-BTO) composite with an objective to examine the possibility of using this composite for humidity sensing. In this work, PANI-BTO composites were synthesized by an in situ chemical oxidative polymerization of aniline in presence of BaTiO3 particles. These composites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM). The electrolyte pH significantly affects the synthesis of PANI-BTO composite. At lower pH, the formation of BaSO4 was observed in the composite which may be due to the leaching of Ba2+ ions from the surface of BaTiO3 particles in HCl medium. The exclusive formation of PANI-BTO composite without BaSO4 was achieved at higher pH (5.7). The PANI-BTO composites show better sensing properties than pure PANI, such as higher response factor and quicker response. The composites with 50 wt% of BaTiO3 exhibit an exponential relationship between the resistance and RH irrespective of electrolyte pH used for the synthesis.