Abstract
Polyaniline (PANI) as a known conducting polymer exists in different forms, each having its own properties and technological applications. Leucoemeraldine, the fully reduced form of PANI has found application in electrochromic devices and Li-PANI batteries. The fully conductive form of PANI, emeraldine salt (ES), has been used in sensor industry, as electromagnetic shielding material, electrochromic devices, and electrode material in batteries. Emeraldine base (EB) is the insulating form of PANI. Some gas sensors same as HCl sensors or corrosion protection material are prepared using EB. Another form of PANI is called pernigraniline, which is used in nonlinear optics. PANI coatings in the form of ES or EB (EB) have demonstrated efficient anticorrosion performance. The ability of PANI in corrosion protection is based on oxidation–reduction reactions. The self-healing ability of PANI is considered as a superior characteristic for corrosion protection of metal substrate. PANI composites and blends have found a wide range of application in various fields such as sensors, biomaterials, solar cells, actuators, batteries, hydrogen storage materials, and so on. Particularly, in this chapter the application of PANI in corrosion protection, electromagnetic interface shielding, energy storage, and composites in addition to future scopes and challenges of PANI-based materials are discussed.