Influence of the toxic vapors on the gas sensitivity and structure of poly(o-toluidine)

Abstract

In the present work, we investigated the influence of the toxic vapors (ammonia, chloroform, tetrahydrofuran, dimethylformamide, nitrobenzene, toluene) on the specific resistance, optical absorption, and structure of conducting polymer poly-o-toluidine (PoT) obtained by oxidative polymerization of o-toluidine in toluene sulfonic acid (TSA) solution. This polymer has a high level of crystallinity and is thermal stable to 473 K (200 0C). The action of organic solvent vapors causes an increase in PoT-TSA resistance by 1.3-1.4 times, while after the action of ammonia, the resistivity increases almost 500 times. The activation energy of charge transfer Ea also increases from 0.21 to 0.71 eV under the action of ammonia due to the deprotonation of the polymer and its transformation to the resistive base form. When the organic solvents are used, the observed phenomena have a different direction (resistance increase or decrease) due to the peculiarities of polymer-solvent molecular interaction. This phenomenon may be used for selective detection of solvents.