Sensing of Higher Alcohols and Selective Sensing of Iso-Amyl Alcohol by Poly (o-Phenylenediamine) Nanofiber

Nanofiber of semiconducting poly(o-phenylen-ediamine) (PoPD) with free =NH functional groups synthesized in dimethyl sulfoxide by reverse salting-out process was employed as chemiresistive sensor for the successful sensing of aliphatic alcohols vapor. The resistivity of PoPD nanofiber in its self-charge separated form was decreased upon exposure of various alcohol vapor, viz., methanol, ethanol, propanol, isopropanol, n-butanol, t-butanol, 1-pentanol, and hexanol with air mixture at room temperature (30±2 °C) and room humidity (65±5%). The film of PoPD nanofiber was responded strongly towards the methanol and ethanol vapor irrespective of their concentration above 50 ppm with air flow due to having strong interaction with such small molecules. However, the vapor of higher alcohols at room temperature could also be detected considering their differences in the % responses at varying concentrations. Interestingly, the film of PoPD nanofiber could be used for selective sensing of iso-amyl alcohol vapor, as the resistivity was increased in presence of vapor of iso-amyl alcohol with air. The sensing mechanism was established on the basis of the different interactions of PoPD nanofiber with the aliphatic alcohols analyzed from the spectroscopic characterizations.