Preparation of water-dispersive poly(3,4-ethylenedioxythiophene) (PEDOT) conductive nanoparticles in lignosulfonic acid solution

Abstract Lignosulfonic acid (LS) has been applied both as dispersant and dopant for chemical polymerization of 3,4-ethylenedioxythiophene (EDOT). EDOT is successfully polymerized in LS aqueous solutions, resulting in a water-dispersive poly(3,4-ethylenedioxythiophene) (PEDOT) conductive nanoparticle (PEDOT:LS). The structure, intermolecular interaction, and performance of the PEDOT:LS were investigated by ultraviolet-visible-Near-infrared spectrophotometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, dynamic light scattering, transmission electron microscopy, X-ray photoelectron spectroscopy, and surface resistivity tester. Results were interpreted in a way that PEDOT:LS is a polyelectrolyte complex, in which the highly hydrophobic PEDOT is in the inner part of the particle and the LS-rich layer with high hydrophilicity is on its surface. During oxidizing reaction of EDOT to PEDOT in LS, the water-insoluble PEDOT product is adsorbed on the surface of water-soluble LS by electrostatic attraction and forms PEDOT:LS polyelectrolyte complexes. In this process, excess LS is needed to be adsorbed on the surface of PEDOT:LS complexes. The process is driven by π-π interaction to increase the water solubility and contributes to a continuous polymerization. The PEDOT:LS as coating has a good conductivity, transparency, humidity resistance, water resistance, and thermal stability and can be used as high-performance antistatic agents.