Influence of different organic solvents and oxidants on insulating and film-forming properties of PEDOT polymer

Processing of conjugate polymers has always been a challenge because of their poor solubility and infusibility in organic and inorganic solvents. The processibility and applications of intrinsically conductive polymers can be enhanced by producing their solutions or dispersions in different suitable solvents. It can also be achieved by preparing undoped or electrically neutral polymers, which can further be transformed in a semiconductor after an oxidation/reduction reaction. The present study focuses on the preparation of active dispersions of poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer in various organic solvents. For this purpose, the polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer was carried out in three different organic solvents, ethanol, 1-butanol, and acetonitrile, with two commonly used oxidants, ferric(III) chloride and ferric(III) p-toluenesulfonate. In this regard, the oxidant and monomer solutions with variable molar concentrations (0.25, 0.5, and 1.0 M) were prepared in particular solvents and then the solutions were mixed with different monomer/oxidant volume ratios. The obtained dispersions of PEDOT can readily be polymerized on the surface of different materials after solvent evaporation and a uniform film can be achieved. The effect of molar as well as volume concentrations of EDOT monomer and oxidant on insulating (undoped/neutral) and film-forming properties of PEDOT was investigated. These dispersions were applied on a transparent PET film and cellulosic fibers (viscose), dried at room temperature and analyzed using scanning electron microscope, optical microscope, and ATR-FTIR spectroscopic analysis. The electrical characterization of undoped PEDOT-coated fibers was performed on Keithley Picoammeter. This study contributes to obtaining a simpler and instantaneous polymerization method of PEDOT preparation and enhancing its application area.