Preparation of nanofibrous polyaniline films and their application as ammonia gas sensor

Silicon substrates were surface modified using an amino-silane ((CH3O)3-Si-(CH2)3NH(CH2)2-NH2) self-assembled monolayer (SAM). The amino groups (NH2) of the amino-silane SAM were employed as artificial seeds for self-organization of polyaniline during chemical polymerization of polyaniline. The polyaniline films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Scanning electron microscopy showed formation of crystalline nanofibrous structure with nanofibers roughly perpendicular to the substrate surface. Chemiresistor sensors formed using these films as a sensitive layer showed sensitivity to very low concentration (0.5 ppm) of ammonia and better response and recovery times in comparison to earlier reports.