Synthesis and characterization of polyaniline/silicon dioxide composites and preparation of conductive films

The focus of this study was to synthesize the inherently conductive polymer polyaniline using an optimized process to prepare polyaniline/silicon dioxide (PANI/SiO 2 ) composites by in situ polymerization and ex situ solution mixing. PANI and PANI/SiO 2 composite films were prepared by drop‐by‐drop and spin coating methods. The electrical conductivities of HCl doped PANI film and PANI/SiO 2 composite films were measured according to the standard four‐point‐probe technique. The composite films exhibited an increase in electrical conductivity over neat PANI. PANI and PANI/SiO 2 composites were also investigated by spectroscopic methods including UV‐Vis, FT‐IR, and Photoluminescence. UV‐Vis and FT‐IR studies showed that SiO 2 particles affect the quinoid units along the polymer backbone and indicate strong interactions between the SiO 2 particles and the quinoidal sites of PANI (doping effect). The photoluminescence properties of PANI and PANI/SiO 2 composites were studied and the PANI/SiO 2 composites showed increased intensity as compared to neat PANI. The increase of conductivity of PANI/SiO 2 composite may be partially due to the doping or impurity effect of SiO 2 where the silicon dioxides compete with chloride ions. The morphology of particles and films were examined by a scanning electron microscope (SEM). SEM measurements indicated that the SiO 2 were well dispersed and isolated in composite films. Copyright © 2009 John Wiley & Sons, Ltd.