ELECTROCHEMICAL ACTIVITY OF POLY(N-VINYLCARBAZOLE) FILMS IN ACETONITRILE SOLUTION AND IN ACETONITRILE PLUS WATER MIXTURES - CORRELATION BETWEEN SPECTROELECTROCHEMICAL AND EPR RESULTS

The redox behaviour of poly( N-vinylcarbazole) (PVCz) films deposited potentiostatically on platinum wire has been studied by means of rever sed current pulse chronopotentiometry, spectrophotometry and EPR spect roscopy. The galvanoslatic method was used to determine the surface co ncentration of the redox centres in PVCz and the formal degree of oxid ation of the polymer at various polarisation potentials in acetonitril e solution of supporting electrolyte. The EPR spectra correlated with UV-visible absorption spectra of the oxidised polymer suggest that pol arons are the majority charge carriers responsible for conductivity of PVCz. Decrease of polaron concentration in acetonitrile + water mixtu res recorded under open circuit condition was interpreted in terms of internal configuration of the polymer backbone. The partial trapping o f the polarons in the polymer matrix was also proved by means of EPR a t high water content (90%) in the acetonitrile solution.