Optoelectronic Functional Polymer Synthesis And Characterization

Four series of conjugated polymers with a thiophene, carbazole, triphenyIamine or phenothiazine moiety in the main chain were designed based on the theory of band gap engineering, and the polymers were synthesized through Wittig, Knovenagel and McMurry condensation reactions respectively, among which 15 polymers was not reported before. The synthesized polymers were characterized by using ~1H-NMR, IR, UV-vis and FL spectroscopies as well as GPC and TGThe influence of different functional group in the main chain on the thermal stability and photophysical properties was investigated. It was found that the introduction of cyano group decreased the thermal stability of polymers PBP, PNP, PQP, which were the most thermally instable ones in the corresponding series of conjugated polymers with a carbazole, triphenylene or phenothiazine moiety. Such a phenomenon was resulted from the formation of a quinoid structure with a longer conjugated length from p-phenylene in polymers PBP, PNP, PQP. The formation of a quinoid structure from m-phenylene was incapable, which made the thermal stability of polymers PBM, PNM, PQM largely increased. On the other hand, the introduction of a cyano group introduced to polymers PBM, PNM, PQM resulted in an enhancement of the intermolecular power. Additionally, polymers PBM and PQM were the most thermally stable ones in conjugated polymers with a carbazole or phenothiazine moiety.From the UV-vis spectra of the dilute solution in THF, the absorption maxima of the polymers with p-phenylene in the polymer main chain were higher than those of the polymers with m-phenylene. The fluorescence and electroluminescence emission maxima followed the same trend as the absorption maxima in THF. In addition, the band gap of the polymers with p-phenylene was less than that of the polymers with m-phenylene. When the geometrical scale of the repeating unit was large enough, the photophysical properties of conjugated polymers was more largely affected in o-phenylene than m-phenylene. The absorption maxima in polymers with thiophene group were larger than those with phenylene group, also the fluorescence and...