Synthesis, Characterization and Electrical Conductivity of Poly(p-phenylene vinylene)


Abstract: Poly(p-phenylene vinylene) (PPV) was prepared electrochemically from p-xylene-bis(diethylsulphonium chloride) in a solvent-electrolyte couple of acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB). The polymer obtained from the electrode surface was converted to PPV by the thermal elimination of diethyl sulfide, HCl and ethyl sulfide. PPV was also obtained chemically in order to investigate the effect of the synthetic method on the structure and electrical conductivity. The characterization of the polymers was carried out by means of fourier transform infrared spectrometer (FTIR), differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA) techniques. The doping effect on the conductivity of the PPV was investigated by using different agents such as H_{2}SO_{4}, I_{2} and metallic Na. It was concluded from the results of spectroscopical investigations that trans-vinylene units are formed on the backbones of polymers obtained by both chemical and electrochemical methods. Thermal analysis data confirmed that the thermal elimination of diethyl sulfide from the polymers obtained by electrochemical and chemical methods are almost complete, and therefore, the resultant product is PPV. It was evident from the TGA results that the polymer obtained chemically had a thermal stability higher than the electrochemically prepared polymer. Although the polymers obtained were insoluble and insulating, they were successfully converted into conducting polymers with the maximum conductivity of 10^{-3} S/cm by doping in solution or in vapor.

Keywords: Conducting Polymers, Poly(p-phenylene vinylene), Electrochemical Polymerization, Doping; Electrical Conductivity

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