Impact of the solvent on the performance of polyaniline-based sensors devoted to ammonia detection

Detection of ammonia is crucial for outdoor air quality since it is a precursor in the formation of fine particles. Its detection is essential in several areas including the agricultural sector where the most of ammonia is emitted through animal waste and nitrogen fertilizers.To monitor ammonia in real-time, many sensing methods exist such as optical, acoustic method or solid-state sensing technologies. Among these latter, the chemiresistive devices based on Conductive Polymers (CP) and more specifically on the polyaniline polymer are a promising greener solution, as they do not require a high temperature to properly work, contrary to the current metal oxide sensors. CP displays advantages to be easily customized, to have a good selectivity, good processability as well as good film mechanical properties such as elasticity.Polyaniline-based sensors may be considered as sustainable sensors, as they are manufactured at low ambient temperatures. Furthermore, the low-energy process requires little material quantities because it occurs by inkjet printing of a solvent-based solution containing the dispersed doped polyaniline. Up to now, solvents identified to disperse the insoluble doped polyaniline were m-cresol, n-methyl-2-pyrrolidone (NMP) or dichloroacetic acid. These solvents raise environmental and toxicity issues, due to their cancerogenic, mutagen reprotoxic and corrosive character. To reach a sustainable manufacturing of polyaniline-based sensors, safer solvents must be found.Therefore, the objective of this study is to identify safer solvents to disperse conductive polyaniline, without impacting drastically its sensing performance. More largely, the influence of the solvent on final properties of the material is investigated, in order to identify and understand structure/properties relationships.Indeed, different conventional and greener solvents are selected and their influence is tested on formulation elaborated according to the same protocol and including polyaniline doped with camphorsulfonic acid (CSA). ...