Two-step cathodic synthesis of poly(para-phenylenevinylene)

The electrochemical behavior of a film, which consists of intermediate products of the alpha,alpha,alpha',alpha'-tetrabromo-para-xylol (TBX) reduction and is deposited on a glassy-carbon electrode from 5 x 10(-2) M TBX solutions, is studied in 0.1 M Bu4NBF4 solution in DMFA by cycling the potential from 0 to -1.4V with respect to an aqueous saturated calomel electrode. When the potential is cycled from 0 to -2.1 V in a cell filled with the supporting electrolyte, the film, which is assumed to have the (-BrHC-C6H4-CHBr-)(n) composition, can be reduced to form poly(para-phenylenevilylene) (PPV). This film exhibits redox activity in the cathodic range in solutions of Bu4NBF4 in DMFA and in both cathodic and anodic ranges in solutions of Bu4NBF4 in AN. It is observed for the first time that, if the cathodic limit of the potential cycling range is extended to -2.5 V, the cathodic doping of PPV at potentials below -2 V disappears and a new reversible redox process takes place at more negative potentials.