Hydrazine detection by polyaniline using fluorinated alcohol additives

A new sensor for hydrazine detection is reported using conventional polyaniline thin films processed from hexafluoroisopropanol. This and other fluorinated alcohols are shown to react with hydrazine to produce a strong acid. The hydrofluoric acid (HF) protonates the emeraldine base form of polyaniline leading to large increases in conductivity-greater than 4 orders of magnitude. In contrast, conventional polyaniline films processed from other organic solvents and polyaniline nanofiber films processed from water become more insulating upon exposure to hydrazine. In these cases, hydrazine acts as a strong reducing agent, converting the emeraldine form of polyaniline to its leucoemeraldine oxidation state. The concept of using additives to enhance the sensing ability of polyaniline films could prove useful for other analytes as well as for other conducting polymers.