UNDOPED POLYPARAPHENYLENE FILMS OBTAINED BY ELECTRO-REDUCTION OF DIBROMOBIPHENYL - INVESTIGATIONS OF NUCLEATION AND GROWTH ONTO INDIUM TIN OXIDE ELECTRODES

The nucleation and growth of poly(para-phenylene) (PPP) films obtained by the electroreduction of dibromobiphenyl in the presence of a Ni(O) catalyst on indium tin oxide (ITO) electrodes has been studied using chronoamperometry and scanning electron microscopy (SEM). Though PPP nucleates as an insulating polymer within the potential range useful to perform the synthesis, both electrochemical data and SEM observations confirmed that formation of the film occurs by progressive nucleation and two-dimensional growth of polymer onto the ITO electrode. At longer times, when the whole surface is coated, the electrode becomes passivated and SEM observations show that the fibrillar morphology of PPP thickens, thus giving a more compact material which does not permit further diffusion to the electrode interface.