A novel formation process of polyaniline micro-/nanofiber network on solid substrates

By a chemical oxidative polymerization of aniline on solid substrates treated with Au nanoparticles (Au-NPs) deposition and 4-aminothiophenol (ATP) modification, polyaniline (PANI) fibers were obtained in micro-/nanosize with two-dimensional network structures. The observation by laser scanning microscopy (LSM) indicated that the formation of PANI fibrous network occurred during the drying process rather than the polymerization. It was suggested the ATP modification on Au-NPs deposited substrate resulted in an inhomogeneous grafting of solution-formed PANI on the solid substrates, which self-aggregated to the fibrous network structure with the evaporation of water due to interchain interactions. The influence of polymerization conditions on the formation of fibrous network and the conducting property of the prepared film were discussed. Results from the gas sensing of the as-prepared PANI sensor upon exposure to NH₃ confirmed that the sensitivity and responding rapidity was improved greatly by the PANI 2D fibrous network structure. Especially, a rapid response in resistance change on NH₃ with low concentration indicated that the developed method in this work can be used to fabricate highly sensitive PANI gas sensors.