Polypyrrole-based methanol sensors prepared by chemical and vapor state polymerization

Polypyrrole (PPy) and polypyrrole-poly (vinyl alcohol) (PVA) composite methanol sensors were prepared by chemical and in-situ vapor state polymerization method, respectively, and their chemical structures were identified by a FT-Raman spectroscopy. The sensing behaviors of two-type methanol gas sensors, such as sensitivity, response and recovery time, reproducibility and long-term stability were investigated by using a flow measuring system including mass flow controller (MFC), temperature controllers and bubbling bottle. The sensitivity of the sensors almost linearly increased with the increase of methanol concentration from 87ppm to 1059ppm. The sensitivity of vapor state polymerized PPy/PVA composite sensor was higher than that of chemically polymerized PPy sensor, while the response and recovery time and long-term stability were worse.