Synthesis and characterization of poly(1,4‐phenylenevinylene) derivatives containing liquid crystalline oxadiazole groups

Two novel poly(1,4‐phenylenevinylene) (PPV) derivatives containing liquid crystalline oxadiazole side chains were prepared by a dehydrochlorination process. The homopolymer poly(2‐methoxy‐5‐((2‐methoxy‐phenyl)‐5‐hexyloxy‐phenyloxy‐1,3,4‐oxadiazole)‐1,4‐phenylenevinylene) (HO–PE 6 ) is insoluble in common solvents, whereas the copolymer poly(2‐methoxy‐5‐((2‐methoxy‐phenyl)‐5‐hexyloxy‐phenyloxy‐1,3,4‐oxadiazole))‐(2‐methoxy‐5‐(2′‐ethylhexyloxy))‐1,4‐phenylenevinylene) (CO–PE 6 ) is soluble in common solvents such as chloroform, THF, and p ‐xylene. The molecular structure of CO–PE 6 was confirmed by FTIR, 1 H‐NMR, UV–vis spectroscopy, and polarized light microscopy. CO–PE 6 showed a maximum emission at 556 nm in chloroform and at 564 nm in solid film, when excited at 450 nm. The maximum electroluminescence emission of the device indium–tin oxide (ITO)CO–PE 6 /Al is at 555 nm. The turn‐on voltage of LEDs based on CO–PE 6 and MEH–PPV is 6.5 and 8.5 V, respectively. The electron mobility of CO–PE 6 is higher than that of MEH–PPV based on the results of current–voltage and electrochemical behavior of both MEH–PPV and CO–PE 6 . © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 396–403, 2004