polianilin

Polyaniline is a synthetic conducting polymer, meaning it possesses electrical conductivity similar to metals, despite being an organic compound. It is one of the most studied and commercially significant conducting polymers due to its ease of synthesis, environmental stability, and tunable properties. Polyaniline exists in several oxidation states, but its most common forms are emeraldine base and emeraldine salt. The emeraldine base is an insulator or semiconductor, while the emeraldine salt form exhibits significant conductivity.

The synthesis of polyaniline typically involves the oxidative polymerization of aniline monomer. This can be achieved through both chemical and electrochemical methods. Chemical oxidation often uses oxidizing agents like ammonium persulfate, while electrochemical polymerization involves applying an electrical potential to an aniline solution. The resulting polymer can be processed in various ways, including solution casting and electrodeposition, to form films and coatings.

Polyaniline's unique properties have led to a wide range of potential applications. These include antistatic coatings, electrodes in batteries and supercapacitors, corrosion protection for metals, electromagnetic interference shielding, and sensing devices. Its conductivity can be altered by doping with acids, which protonates the polymer chain and increases charge carrier concentration. The color of polyaniline also changes depending on its oxidation state and doping level, contributing to its use in electrochromic devices, which can change color upon application of a voltage. Research continues to explore new synthesis techniques and functionalization strategies to further enhance its performance and expand its application scope.