Synthesis and optical properties of poly(2,7-(9,9-dihexylfluorene)-3,3′(4,4′-dialkoxybiphenyl))

Five new polymers were synthesized by Suzuki coupling reaction using 9,9-dihexylfluorene-2,7-diboronic acid and 3,3′-dibromo-4,4′-dialkoxybiphenyl as the starting materials. The synthesized alternating copolymers were characterized using gel permeation chromatography, 1H and 13C NMR, FT-IR, optical absorption and emission spectroscopic techniques. The thermal behavior of these polymers was analyzed using thermal gravimetric analysis and temperature modulated differential scanning calorimetric studies. The thermal studies show all the polymers were stable up to 300 °C and the glass transition temperature depends on the alkyl chain length. All the polymers have absorption around 330 nm in solution as well as in film, whereas the polymers have emission around 390 nm in both solution and film. Absorption and emission properties of the synthesized materials are not significantly different in solution, but are dramatically different as thin films at different annealing temperatures.