Assembly and Interaction of Polyaniline Chains: Impact on Electro- and Physical–Chemical Behavior

Polyaniline (PANI) is one of the promising candidates for utilization as electrode material in supercapacitors, and its electro- and physical–chemical properties have been studied for several decades. However, there are fundamental questions that need to be answered. For example, is it possible to obtain and characterize individual PANI chains or what is the impact of chains interactions on electro- and physical–chemical behavior? To that end, we isolated and characterized individual PANI chains alongside nanofibrillar assemblies for the first time, and moreover, we demonstrate that the interaction between polyaniline chains and their assembly into nanofibrils have a crucial impact on electro- and physical–chemical behaviors of PANI. Additionally, the optical transitions of three different conglomerations and protonation states are studied and correlated with the structural and electrochemical characterization. The mechanism of the redox process for individual PANI chains and PANI nanofibrils is proposed. The specific capacitance of 1050 F/g (at 25 A/g of specific current) for three-electrode configuration and 450 F/g (at 9 A/g of specific current) for two-electrode configuration was obtained, which is the highest value reported to date.