In situ external reflection Fourier transform infrared spectroscopic study on the structure of the conducting polymer poly(paraphenylene)

Abstract

In situ external reflection FTIR measurements have been performed during cyclic voltammetric polymerization of poly(paraphenylene)(PPP) films. The films were made either in 0.05 or 0.2 mol dm^–3 biphenyl solutions using acetonitrile as the solvent and tetrabutylammonium tetrafluoroborate (TBABF₄) as the electrolyte salt. Changes in the IR spectrum of different PPP films were studied when the synthesis was achieved by using different concentrations of the starting material and different cycling potential ranges for polymerization. When the concentration of biphenyl was 0.2 mol dm^–3 and the end potential of the cyclic scan was 1.6 V versus an Ag/AgCl/KCl (3 mol dm^–3) reference electrode, a high level of mono-substituted units in the polymer material was present. Films obtained by using 0.05 mol dm^–3 biphenyl solution and the end potential 1.8 V for the cyclic scan resulted in a PPP film consisting of long and crosslinked chains. Differences between the first and subsequent cyclic potential scans could be observed.