Effect of Morphology on the Response of Polyaniline-based Conductometric Gas Sensors: Nanofibers vs. Thin Films

Mixtures of methanol with increasing fractions of formic acid were used to progressively transform the morphology of polyaniline starting from nanofibers to compact conventional films. It was demonstrated that the methanol/formic acid mixture could be used as a viable solvent system for nanostructured polyaniline to achieve sufficient processability while maintaining its microstructure. The effects of morphology on the response of polyaniline-based conductometric sensors to neutral gas molecules were also examined. Although the nanofiber films demonstrated faster responses, they exhibited lower sensitivity than conventional thin films. Creating high surface area nanofibril structures in polyaniline film does not appear to effectively enhance sensor sensitivity due to the relatively open structure inherent to many polymeric materials and the adverse contribution from the interfibrillar contact resistance associated with nanofiber films.

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