Tuning the Molecular Sensitivity of Conductive Polymer Resistive Sensors by Chemical Functionalization

Abstract

Polyaniline thin films are chemically functionalized by nucleophilic addition of thiols beareing different functional groups: carboxylic, amine, -dodecyl and sulfonic. The modification is tested using FTIR and XPS spectroscopy. Then, the films are used as resistive sensors for different volatile organic compounds in a static measuring system. The sensitivity of conducting polymers to alcohols and heptane is strongly affected by the chemical functionalization of the materials. Polyaniline show an increasing signal when the chain length of different alcohols is increased. The incorporation of hydrophilic groups on the PANI chains seems to maintain the trend. On the other hand, the polymer modified with a long alkyl chain (PANI-DOT) show negative response for methanol and the signal increases up to propanol to decrease for longer chains. PANI-DOT show the largest signal for heptane of all polymers tested. Therefore, the functional group attached to the conductive polymer chain can be used to tune the molecular sensitivity of the resistive sensor