Ammonia absorption study of pulsed-plasma polyaniline by quartz crystal microgravimetry and UV/vis spectrometry

The ammonia absorption properties of polyaniline elaborated by the pulsed-plasma technique are studied. These properties depend on the structure of the polymer which is associated not only to plasma parameters such as peak power, ignition and extinction durations, pulse frequency and duty cycle, but also to the type of doping agent. Two methods of analysis are used: the UV/vis spectrometry and the quartz crystal microbalance. The results show that input power is the most influent plasma parameter on the sensitivity of the polyaniline film. Moreover, the oxidative doping is more efficient than the acidic one to create more polarons and then to obtain a more sensitive layer. The gravimetric study shows that the interaction between ammonia molecules and iodine-doped polyaniline corresponds to a multilayer reversible chemisorption.