(217ey) Green Chemistry Synthesis of Nanostructured Polyaniline and Its Derivatives

We report a facile high-ionic strength system for synthesizing bulk quantities of parent polyaniline, o-alkyl and o-alkoxy ring-substituted polyanilines in one step by chemical oxidative polymerization of the corresponding monomers under aqueous acidic conditions using hydrogen peroxide (H₂O₂) as a mild, environmentally benign oxidant. Conventional polyaniline synthesis involves the use of the oxidizing agent, ammonium peroxydisulfate (APS), which produces the undesirable waste product, sulfuric acid; this is avodied through the use of hydrogen peroxide as the oxidizing agent, which produces water as the waste product. The high ionic strength medium used (1M HCl/ 5M CaCl₂) also produced highly conducting, low defect parent polyaniline. The nanostructured polyaniline obtained from this system can be cast as a film with low thickness and high conductivity through the secondary dopant technique. Additionally, when the ionic strength of the medium used to synthesize the polyaniline derivates is lowered by changing the chloride salt used, novel, high surface-area nanostructures are formed.