Conducting PEDOT Nanoparticles: Controlling Colloidal Stability and Electrical Properties

The synthesis of conducting polymer nanoparticles by oxidative polymerization can be a challenge because the addition of oxidizers may compromise the colloidal stability of the system. In this work, we report the successful synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles by means of miniemulsion polymerization. We study the role of oxidizing agents (iron(III) p-toluenesulfonate and hydrogen peroxide) during the particle formation and in the electric properties. The presence of hydrogen peroxide is demonstrated to be crucial in the macroscopic stability of the suspensions and in the morphology of the resulting nanoparticles. The obtained suspensions, containing particles of diameters of around 30 nm, are stable for several months. The electrical conductivity increases with increasing the content of iron(III) p-toluenesulfonate, but it decreases with addition of hydrogen peroxide, which can be explained by secondary reactions in the polymerization process.