Poly [2,7-(9,9-dihexylfluorene)-alt-pyridine] with donor-acceptor architectures: A new series of blue-light-emitting alternating copolymers

A novel series of well-defined alternating poly[2,7-(9,9-dihexylfluorenyl)alt-pyridinyl] (PDHFP) with donor-acceptor repeat units were synthesized using palladium (0)-catalyzed Suzuki cross-coupling reactions in good to high yields. In this series of alternating polymers, 2, 7-(9,9-dihexylfluorenyl) was used as the light emitting unit, and the electron deficient pyridinyl unit was employed to provide improved electron transportation. These polymers were characterized by H-1-NMR and C-13-NMR, gel permeation chromatography (GPC), thermal analyses, and UV-vis and fluorescence spectroscopy. The glass transition temperature of copolymers in nitrogen ranged from 110 to 148degreesC, and the copolymers showed high thermal stabilities with high decomposition temperatures in the range of 350 to 390degreesC in air. The difference in linkage position of pyridinyl unit in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film phases. Meta-linkage (3,5- and 2,6-linkage) of pyridinyl units in the polymer backbone is more favorable to polymer for pure blue emission and prevention of aggregation of polymer chain than para-linkage (2,5-linkage) of the pyridinyl units. (C) 2004 Wiley Periodicals, Inc.