Influence of counter ion on polyaniline and polypyrrole

The electronic, magnetic, optical and redox properties of conjugated polymers are greatly influenced by structure, electronegativity, solvation and orientation of a counter ion. The doping by counter ion not only creates a band structure but also stabilizes localized bound states to impart unusual optical and magnetic properties to macromolecular system. When the polymer is in contact with solution of an electrolyte, counter ion tends to be solvated and mobile in the polymer phase, imparting it a property of ion exchange membrane. Here we briefly summarize the influence of anion on properties and electrochemical behaviour of polyaniline and polypyrrole.