Phenoxazine-Containing Polyaniline Derivatives with Improved Electrochemical Stability and Processability

Abstract

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.

Electrochemically Stable Carbazole-Derived Polyaniline for Pseudocapacitors

“…We recently reported the synthesis of a phenoxazine PANI derivative that showed excellent electrochemical stability . However, phenoxazine is expensive, and its preparation requires a multistep approach.…”

“…As such, the electrical conductivity of the polymers was determined using a four-point probe apparatus. Films of Cbz-PANI-1 and Cbz-PANI-2 were prepared by drop-casting a 5 mg/mL EtOH solution of the polymers onto the substrate, which were then subjected to slow drying over m -cresol vapor at 100 °C for 24 h. In our previous studies, it was shown that m -cresol increased the conductivity by changing the morphology of the polymers from aggregated particles to thick sheet-like structures . The conductivity was determined to be 2.82 S cm –1 for Cbz-PANI-1 and 0.70 S cm –1 for Cbz-PANI-2 .…”

“…The common approach is to dope the polymer with large counterions or prepare nanostructures. , However, these approaches have not been overwhelming successful. Recently, we reported a PANI-derivative containing a phenoxazine moiety that was stable over 100 CV cycles without noticeable degradation . However, phenoxazine is expensive and requires a multistep synthesis for its preparation.…”

Evaluation of the Passivation Effects of PEDOT:PSS on Inverted Perovskite Solar Cells

“…The P1 and P2 polymers were synthesized according to a previous work. [162,163] 1 H NMR spectra were recorded on a Bruker spectrometer (500 MHz) in deuterated solvent at room temperature. The chemical shifts were expressed in parts per million (ppm) downfield from SiMe 4 after the NMR data were processed by Mestre Nova.…”

Spectroelectrochemistry of Electroactive Polymer Composite Materials

“…Almtiri et al [ 125 ] have prepared two PANI derivatives that contain a phenoxazine unit copolymerized with 2,5-dimethyl-p-phenylenediamine and p-phenylenediamine and determined their electrochromic properties. PANI nanofilaments were obtained by electropolymerization of aniline through the vertically aligned silica nanochannels [ 126 ] .…”