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-PE6) is insoluble in common solvents, whereas the copolymer poly(2-methoxy-5-((2-methoxy-phenyl)-5-hexyloxyphenyloxy-1,3,4-oxadiazole))-(2-methoxy-5-(2'-ethylhexy- loxy))-1,4-phenylenevinylene) (CO-PE6) is soluble in common solvents such as chloroform, THF, and p-xylene. The molecular structure of CO-PE6 was confirmed by FTIR, H-1-NMR, UV-vis spectroscopy, and polarized light microscopy. CO-PE, 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-PE6/Al is at 555 nm. The turn-on voltage of LEDs based on CO-PE6 and MEH-PPV is 6.5 and 8.5 V, respectively. The electron mobility of CO-PE6 is higher than that of MEH-PPV based on the results of current-voltage and electrochemical behavior of both MEH-PPV and CO-PE6. (C) 2003 Wiley Periodicals, Inc. J Appl Polyrn Sci 91: 396-403, 2004.