Natural degradation of polypyrrole nanowires in NaOH solutions and its degradation kinetics

The polypyrrole (PPy) nanowires doped with p-toluenesulfonate ions (PPy/pTS NWs) are prepared and degraded in aerated and deaerated NaOH solutions (CNaOH=0.02 - 0.5 M) for different times to examine their natural degradation behavior and kinetics. After degradation, the fluffy PPy/pTS NWs network film generally exhibits a uniform natural degradation state with apparent damaged areas on the nanowires' surface, decreased nanowire diameter, and increased film thickness. The electroactivity degradation of PPy/pTS NWs still follows the firstorder degradation kinetics, like the bulk-structured PPy/pTS films. The natural degradation kinetics model established from the bulk-structured PPy films is proven to apply to PPy/pTS NWs. The rate equations for the chemical and electrochemical degradation of PPy/pTS NWs in NaOH solutions are determined. Additionally, it is confirmed that the electrochemical degradation process is the dominant factor, while CNaOH significantly impacts the chemical degradation process. The structural features of PPy/pTS NWs do not alter the chemical and electrochemical degradation processes but significantly accelerate the degradation rates. This research will contribute to our understanding of the degradation kinetics of PPy nanomaterials and support their practical applications.