Polypyrrole and Polyaniline Doped With Lignosulfonic Acid

Experiments have shown that electrically conductive polymers with water-soluble fractions can be synthesized by polymerization of pyrrole or aniline in the presence of lignosulfonic acid, which is a polymeric acid that can be derived relatively easily from the spent sulfite liquor byproducts obtained from processing of wood pulp into paper. In these syntheses, the lignosulfonic acid serves as both a dopant and a template for polymerization. Like other lignin derivatives, lignosulfonic acid can be photochemically and thermally cross-linked. The electrical conductivities of the polymers range from 10 –6 to 10 –3 S·cm –1. The combination of electrical conductivity, water-solubility, and cross-linkability provides additional versatility for the development of electrically conductive polymers for such applications as antistatic coating of fabrics and shielding electronic equipment against electromagnetic interference.