Polyaniline blended with polyvinyl alcohol for ammonia sensing

Conducting polyaniline (PAni) was one of the important materials as an ammonia gas sensor. In this work, chemically synthesized and blended polyaniline-polyvinyl alcohol films (PAni-PVA blended film) were prepared for ammonia sensing. Blended PAni-PVA showed a lot of promise in terms of fabrication In addition, conductivity and stability of the blended film were improved by doping PAni and cross-linking PVA with citric acid. FT-IR spectra and SEM micrograph illustrated a good conducting ability and excellent morphology of this film. The conductance of the film increased when exposed to ammonia gas. The conductance of PAni-PVA blended films on an exposure to 90 ppm of ammonia gas was ranging from 19 to 340 nS depending on the amount of citric acid doped. Among those, PAni-PVA blended film with 4% w/v citric acid gave the most excellent ammonia sensing in term of conductance changing and responding time. Film thickness as well as operating temperature and humidity also influenced the sensing of PAni-PVA blended film. The optimized condition was using a 0.15 – 0.20 mm film thickness operating at room temperature (30๐C) and 60%RH. This film The ammonia sensing of this film was reversible. The response and recovery time were 10 and 20 minutes, respectively. The responses of repeated sensing of ammonia gas were reproducible up to 9 cycles. In the presence of 10 to 100 ppm of ammonia gas, the changes of conductivity were well related to the concentration of ammonia gas.