Sensing characteristics of polypyrrole-poly(vinyl alcohol) methanol sensors prepared by in situ vapor state polymerization

Polypyrrole (PPy)-poly(vinyl alcohol) (PVA) composite and pure polypyrrole methanol sensors were prepared by an in situ vapor state polymerization method and their chemical structures were identified by a FT-Raman spectroscopy. The various electrical sensing behaviors of both types of sensors were systematically investigated by a flow measuring system including mass flow controller (MFC) and bubbling bottle. The incorporation of PVA into the polymer film caused a higher sensitivity than that of pure PPy sensor, while the response and recovery time and long-term stability were worse. The effect of thickness of sensing film was also investigated, and it was found that the thinner film showed higher sensitivity, which indicated that the resistance involved in sensing behavior comes from bulk resistance of sensor rather than surface resistance.