NOVEL CONJUGATED POLYMER CONTAINING AROMATIC RING AND SELENIUM IN BACKBONE - ADDITION POLYMERIZATION OF 1,4-BENZENEDISELENOL TO 1,4-DIETHYNYLBENZENE

A novel addition polymerization of 1,4-benzenediselenol (BDSe) to 1,4-diethynylbenzene (DEB) was carried out by UV-irradiation in toluene at 60-degrees-C under nitrogen atmosphere. The polymerization proceeded at such a fast rate as to give 60-70% yield for 6 min. A pale-yellowish polymer (M(n)BAR, = 20000-30000) precipitated with the progress of the polymerization. In the presence of BPO, the polymerization also proceeded rapidly to give the polymer (M(n)BAR = 18000) in 50% yield for 4 min. The polymer (CH = CH-circled hexagon-CH = CH-Se-circled hexagon-Se)n was insoluble in conventional organic solvents. In the IR spectrum of the polymer, the characteristic absorption bands of cis- and trans-vinylene groups appeared at 1340 and 940 cm-1, respectively. The microstructures of polymers were evaluated as the cis content was 90% and the trans one was 10%, based on the model adducts of benzeneselenol and ethynylbenzene. The cis --> trans isomerization occurred with UV-irradiation: the cis vinylene group of the polymer decreased from 90 to 40% for 18 h. The electrical conductivity of the polymer was in the order of 10(-13) S/cm without dopant, but increased up to 10(-5) S/cm on I2 doping. DSC and TG thermograms of the polymer indicated its decomposition point as 465-degrees-C under nitrogen atmosphere.