Sensing of ethanol and other alcohol contaminated ethanol by conducting functional poly(o-phenylenediamine)

Abstract

Poly(o-phenylenediamine) with amine (–NH2) functional group substitutions was chemically synthesized from the monomer o-phenylenediamine using ammonium persulfate oxidant in sulphuric acid medium. The synthesized polymer was soluble in organic solvent like dimethyl sulfoxide (DMSO), dimethyl formamide, etc. The sensing layer was fabricated by a simple drop coating method using the polymer solution in DMSO and the layer was doped with sulfuric acid doping using optimized doping conditions. An average resistance of the doped polymer layer was observed as 2–5 MΩ. The doped conducting polymer layer was used as chemiresistor for the successful sensing of ethanol and methanol or isopropanol contamination in ethanol. The response of doped polymer layer was examined under continuous flow of methanol, ethanol, isopropanol, ethanol/methanol, and ethanol/isopropanol with air mixture at room temperature (25 ± 3 °C) and room humidity (65 ± 5%). The sensing mechanism for doped functional poly(o-phenylenediamine) through –NH2 group substitutions was explored with the help of various standard characterizations.