Electrochemical synthesis of poly (4,4′-biphenylenevinylene)s (PBPVs)

A series of three 2,2'-substituted 4,4'-dimethylbiphenyls have been prepared either by Grignard or Ullmann reactions and their benzylic bromination with NBS gave the corresponding 4,4'-bis (dibromomethyl)biphenyls. The cathodic reduction of these compounds, at a stirred mercury pool cathode led to the desired poly(4,4'-biphenylenevinylene)s, PBPVs, in good yields and in very smooth conditions. The obtained polymers have been spectroscopically characterized. After doping with iodine vapours, they exhibited electrical conductivities of the same magnitude as those observed for parent PPVs. Thermal analysis data (DSC and TG) are also presented and show their thermal stability both in air or nitrogen atmosphere.