On the electrochemical polymerization of poly(p-phenylene vinylene) and poly(o-phenylene vinylene)

This paper describes the electrochemical synthesis of poly(p-phenylene vinylene) and poly(o-phenylene vinylene), via potentiostatic cathodic reduction of α,α,α′,α′-tetrabromo-p-xylene and α,α,α′,α′-tetrabromo-o-xylene. The polymerization yield obtained from the electrochemical quartz crystal microbalance were 88 and 25% for poly(p-phenylene vinylene) and poly(o-phenylene vinylene), respectively. The films were characterized by infrared spectroscopy. The polymer has been identified by the vibrational features characteristic of the trans-vinylene units (3024 and 965 cm−1 for the p-PPV and 2991 and 1002 cm−1 for the o-PPV). A quinoid structure has been identified, indicating that the polymer is partially doped, probably the Br2, formed during the polymerization process. The insoluble phase was identified as p-PPV and o-PPV oligomers by the characteristic bands of the vinylene group. The p-PPV presents oligomers with molar mass corresponding to oligomers of seven monomeric units, while the o-PPV presents shorter chains, probably containing three to four units, as determined by gel permeation chromatography.