Resistive Sensors for Organic Vapors Based on Nanostructured and Chemically Modified Polyanilines

Resistive sensors for organic vapors were made using polyaniline (PANI) and functionalized PANI as thin films or deposits of PANI nanofibers. PANI thin films were synthesized by in situ chemical polymerization onto flat polyethylene films. PANI nanofibers were produced by interfacial polymerization. Both polymeric materials were chemically modified through aromatic electrophilic substitution or nucleophili addition and used as active materials in resistive sensors. The analysis of the resistance-time sensor profiles suggested that chemical modification affects strongly the sensor response. Moreover, the magnitude, the sign, and the rate of the sensor response showed differences for active materials with the same chemical structure and different morphologies. It is demonstrated that using only one conducting polymer but creating material diversity by chemical functionalization or morphological changes different sensors responses for the same volatiles can be obtained. This behavior allows a simple way to produce sensors arrays which can be used in electronic noses.