Solvents polyaniline electrochemical polymerization

Watanabe et al. [161] reported that doped polyaniline can be partially solubilized. A blue film, which was insoluble in organic solvents, was electrochemically polymerized from an aqueous solution of 0.1 M aniline and 0.1 M sulfuric acid. On placing the polyaniline in a 20% by weight aqueous sodium hydroxide-tetrahydrofuran solution, the polyaniline dissolved into the organic layer as indicated by the appearance of a blue color. However, for extraction times in excess of 1 h, the blue color of the tetrahydrofuran phase fades. Most likely, the sulfate dopant anions begin reacting with the sodium hydroxide. 

Ideal electrochemical polymerization was considered to give ideal linear and conjugated polymeric chains. The real situation is that films electrogenerated from the basic monomers are insoluble and infusible. Only polyaniline films are partially soluble in some solvents. 

Most 2,5-unsubstituted pyrroles and thiophenes, and most anilines can be polymerized by electrochemical oxidation. For pyrroles, acetonitrile,54 or aqueous55 electrolyte solutions are normally used, while the polymerization of thiophenes is performed almost exclusively in nonaqueous solvents such as acetonitrile, propylene carbonate, and benzonitrile. 0 Polyanilines are generally prepared from a solution of aniline in aqueous acid.21 Platinum or carbon electrodes have been used in most work, although indium-tin oxide is routinely used for spectroelectrochemical experiments, and many other electrode materials have also been employed.20,21... 

Fully sulfonated polyaniline nanoparticles, nanofibers and nanonetworks have been obtained by electrochemical homopolymerization of o-aminobenzenesulfonic acid for the purpose of mediating the electrochemistry of cyctochrome c [252]. The nanostructures were synthesized in a mixed solvent of acetonitrile and water (8 1) at 0°C by following a three-step galvanostatic procedure. First, a relatively high current density is applied to initiate the polymerization. This is followed by two periods during which lower current densities are applied. 

---