Chemical synthesis of a polyaniline/gold composite using tetrachloroaurate

The chemical synthesis of polyaniline (PANI) is explored using tetrachloroaurate, AuCl4-. These studies provide a simple method for the oxidation of aniline by AuCl4- and simultaneous formation of bulk quantities of a PANI/Au composite. In situ UV/vis spectroscopy indicates that the rate of formation of gold colloids and intermediate (short-chain) PANI species is rapid in comparison to that of the long-chain PANI. Longer PANI chains are produced at a slower rate, at the expense of short-chain intermediate species. The gold particles act as nucleation sites for the oxidative formation of PANI, encapsulating the metal in the form of a polymer/metal composite. Results from the elemental analysis and the FTIR spectra of the composite material are consistent with PANI produced using only ammonium persulfate as the oxidant. In addition, XPS, optical microscopy, and TEM diffraction show that the gold particles are polycrystalline with relatively constant diameter (0.8-1 mum). Finally, the PANI/Au/HBF4 conductance does not change significantly with the introduction of Au particles, relative to that of PANI/HBF4 without Au particles. These studies provide a new method for growth of PANI/metal composites where the presence of the metal in the polymer does not adversely affect the electronic structure.