Morphology, Structure, and Gas Sensing Performance of Conductive Polymers and Polymer/Carbon Black Composites Used for Volatile Compounds Detection

In this paper, we present fabrication, characterization, and sensing performance of four sensor elements, including two conducting polymers (polypyrrole and polyaniline), and two polymer/carbon black (CB) composites consisting ethyl cellulose (EC) and poly(caprolactone) (PCL). The identifications of four different vapors (methanol, ethanol, acetone, and ammonia) by these four sensors have been successfully demonstrated by using the principal component analysis. The sensing mechanisms of the examined sensors were investigated and a discussion on the similarity of gas sensor responses and the creep behavior has also been given. It was found that the response/recovery behavior of gas sensors can be presented by the Kelvin-Voigt rheological model. The effect of CB content on polymer/carbon sensor performance was investigated in the range of 15-20 wt. %. The increase of CB wt. %, led to increase the sensor response. The morphology of the produced EC/CB and PCL/CB composite sensors has been characterized by scanning electron microscopy and atomic force microscopy. Polyaniline indicated the highest response to ammonia due to effect of p-phenylene resonance on deprotonation process. The PCL/CB sensor response was more pronounced as compared with EC/CB, due to its higher porous structure.