IN-SITU ATR-FTIR-INVESTIGATIONS AND RAMAN-INVESTIGATIONS ON THE POLYMERIZATION OF 2,2'-THIENYLPYRROLE AND THE REDOX BEHAVIOR OF THIN-FILM POLY(THIENYLPYRROLE) ELECTRODES IN AQUEOUS-ELECTROLYTES

The polymerization of 2,2'-thienylpyrrole and the redox behaviour of t he resulting polymer film electrodes were studied in order to improve the stability and the response time of miniaturized thin film pH-senso rs based on this polymer. The polymerization process was studied in aq ueous solutions of different pH containing NaClO4, LiClO4 and NaBF4. I n electrolytes containing perchlorate ions dense and homogeneous poly( thienylpyrrole) films were produced exhibiting a conductivity ranging between 0.1 and 0.3S.cm(-1). During in situ FTIR-ATR experiments, the detection of oligomeric structures was not possible. The polymerizatio n of the monomer starts in a very narrow potential range quite rapidly and by in situ Raman spectroscopy an intermediate state was detectabl e during potentiostatic polymerization. The poly(thienylpyrrole) films exhibit in perchlorate containing electrolytes in the pH range 1 to 8 a relatively reversible and similar redox behaviour. In contrast to p oly(thienylpyrrole) films produced in non-aqueous electrolytes, the fi lms polymerized in aqueous media show at higher redox cycles (>1000) a reduced stability connected with a reduced degree of reversibility.