Spectroscopic investigation of oxidation of p-toluene sulfonic acid doped polypyrrole

Oxidative degradation of electrochemically synthesized p-toluene sulfonic a cid doped polypyrrole, PTS-PPY was studied by the application of evolved ga s analysis using IR spectroscopy and direct insertion probe pyrolysis mass spectrometry techniques. It has been observed that PPY films prepared in aq ueous media contained high concentration of oxygenated species even if the synthesis potential was kept low. The extent of overoxidation associated to ketone formation increased by increasing the applied potential and thermal ageing. The decrease in conductivity is attributed to the replacement of d opant, as a result of nucleophlic attack on the polycationic chain, by hydr oxide and/or O-2. Pyrolysis analyses also indicated that chemically prepare d samples were oxygenated in air more readily and yielded mainly C=O groups . Presence of hydroxide groups for these samples may be associated with the adsorption of H2O in air or H2O present during synthesis as an impurity. T he direct insertion probe pyrolysis mass spectrometry technique was shown t o be a very powerful technique for not only determining the thermal decompo sition products but a investigating the interaction of dopant and oxygenate d species with the polymer matrix. (C) 2001 Elsevier Science B.V. All right s reserved.