Synthesis and characterization of conjugated triblock copolymers

A series of conjugated triblock copolymers containing hole-transporting polycarbazole segments, electron-transporting polyoxadiazole segments, and bluelight-emitting polyfluorene segments were prepared with a two-step palladiumcatalyzed Suzuki polycondensation (SPC). First dibromo-terminated polymer precursors (polyfluorenes and polyoxadiazoles) were synthesized as the central building blocks. Then, the dibromo-terminated polymer precursors were further polymerized with AB-type monomers [2-bromo-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9-octylearl)azole, 3-bromo-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9octylcarbazole, and 2-bromo-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-dioctylfluorenel to achieve the target triblock copolymers under SPC conditions. The formation of the triblock copolymers was confirmed by gel permeation chromatography and NMR spectroscopy The triblock copolymers exhibited good thermal stability. An investigation of the photophysical properties indicated that efficient, photoinduced through-bond energy transfer occurred in such triblock copolymer systems. (C) 2007 Wiley Periodicals, Inc.