Synthesis and properties of hyperbranched polymers containing heteroaromatic

The hyperbranched polymers containing heteroaromatic were synthesized by polycyclotrimerizations of 3,5-bis-(4-ethynyl-phenyl)-4-phenyl-4H-1,2,4- triazole, and 2,5-bis-(4-ethynyl-phenyl)-1,3,4-oxadiazole with 1-octyne catalyzed by CpCo(CO)₂-h υ in toluene. The structures and properties of the polymers were characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. The synthesized polymers are completely soluble in common solvents as toluene, THF, chloroform, and dichloromethane. These polymers possess good thermal stability. They graphitize in high yields (up to 75%) when pyrolyzed at 800°C. Upon photoexcitation, the polymers emit a strong deep blue light of ∼400 nm with high quantum yields (up to 80%). The LUMO values of the polymers are close to that of aromatic poly(1,3,4-oxadiazoles), revealing that these polymers exhibit good electron transport property, being a good candidate of electron transport materials in organic light-emitting diodes.