Phenoxazine-Containing Polyaniline Derivatives with Improved Electrochemical Stability and Processability

Polyaniline (PANI) is one of the most accessible conducting polymers and is known for its environmental stability in its partially oxidized conductive state. However, it is difficult to process and undergoes electrochemical degradation between its partially and fully oxidized states. While there have been several approaches to address PANI's processability, little has been done to address its electrochemical instability. We have prepared two polyaniline derivatives that contain a phenoxazine unit copolymerized with 2,5-dimethyl-p-phenylenediamine (P1) and p-phenylenediamine (P2) and determined their optoelectronic properties, processability, morphology, and electrochemical stability. Camphor sulfonic acid (CSA) doped polymers were dissolved in organic solvents and cast into films, which were analyzed by absorption spectroscopy, cyclic voltammetry, and conductivity measurements. Importantly, the films exhibit outstanding electrochemical stability over multiple redox and spectroelectrochemical cycles and conductivity in the high semiconductive regime (0.1 to 1 S/cm) when exposed to m-cresol vapors. Additionally, P1 exists as aggregates in the absence of m-cresol vapors, but as highly conductive sheet-like structures in the presence of m-cresol as shown by SEM, TEM, and AFM images. These results show that P1 and P2 would be outstanding candidates for applications that required stable redox conductive polymers.