Preparation and characterization of conductive polyaniline/silica hybrid composites prepared by sol–gel process

A method had been developed to cast organic/inorganic hybrid composites by sol–gel process. This procedure was mainly controlled by the pH of mixing circumstances of organic/inorganic multicomponent solutions and was attributed to the solvent pH. Cast composite from m-cresol solution could not form a uniform hybrid composite film due to the indistinguishable growth and aggregation of silica at pH<7 in sol–gel processing. On the other hand, hybrid composite cast from N-methyl-2-pyrrolidone (NMP) solution could form a uniform, crack-free film because of its stable silica particle growth according to the mutual repulsion at pH>7. But bulk conductivity from m-cresol solution was higher than that from NMP solution, which resulted from the secondary-doping effect of the solvent. These conformational changes of the polymer chain and ability to form hybrid composite film were analyzed by means of Fourier-transform infrared (FTIR), wide-angle X-ray diffraction (WAXD), microdielectrometer, thermogravimetric analysis (TGA), and conductivity measurements.