Water-Dispersed Conductive Polypyrroles Doped with Lignosulfonate and the Weak Temperature Dependence of Electrical Conductivity

The water-dispersed conductive polypyrroles (PPys) were prepared via the chemical oxidative polymerization with lignosulfonate (LGS), an inexpensive byproduct from pulp processing industries, as a dopant and template for tuning the properties of polypyrrole nanoparticles. The lignosulfonate doped polypyrrole (PPy/LGS) nanoparticles were characterized with Fourier transform infrared (FTIR), UV−vis, thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and electric conductivity. The diameters of the PPy/LGS nanoparticles decreased from 100 to 20 nm with the increasing LGS. Their electrical conductivities were affected markedly by the dopant amount added. The PPy/LGS have weakly temperature-dependent conductivity over the entire temperature interval from 283 to 423 K.