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 (C) 2009 John Wiley & Sons, Ltd.