CONDUCTIVITY, MAGNETIC-SUSCEPTIBILITY AND NUCLEAR-RELAXATION, AS A FUNCTION OF AGING IN POLYPYRROLE

Stability of conducting polymers is of prime importance for their use in practical applications. In this work we report conductivity, ESR experiments and relaxation time on aged polypyrrole powder, synthesized in water by FeCl3 oxidizing polymerization of pyrrole. Samples are heated to 140 degrees C to accelerate the ageing process. Results give evidence for a linear relationship between RPE linewidth and diffusion coefficient along the chains: due to the decrease of spin mobility as a function of ageing, the ESR linewidth broadening, attributed to strong collisions between polarons against fixed iron paramagnetic center, decreases with time.