Fabrication of polypyrrole–phenylalanine nano-films with NH₃ gas sensitivity

Polypyrrole (PPy) films complexed with phenylalanine were successfully synthesized via one-step emulsion polymerization. By incorporating phenylalanine into the conductive PPy backbone, highly functionalized PPy films have been produced and found to respond to ammonia gas. The chemical sensors based on the PPy–phenylalanine nanoparticle films displayed enhanced reproducible and reversible responses upon exposure to NH₃ gas. Their response was strongly dependent on the amount of the phenylalanine. The PPy–phenylalanine films were characterized by UV, IR, and XPS spectroscopy and compared to the PPy films. The gas detection and reversible response mechanism are discussed on the basis of these analysis results.