Fluorinated copolyimides derived from 4,4'-oxydiphthalic anhydride (ODPA) with 4,4'-oxydianline (ODA) and trifluoromethyl-containing aromatic diamines have been synthesized and characterized. The trifluoromethyl-containing diamines include 2,4-diamino-3'-trifluoromethylazobenzene, 2,4-diamino-1-[(4'-trifluoromethylphenoxy) phenyl] aniline, 3,5-diamino-1-[(4'-trifluoromethylphenoxy) phenyl] benzamide, 3,5-diamino-1-[(3'-trifluoromethyl) phenyl] benzamide, 1,4-bis(4'-aminophenoxy)-2-(3'-trifluoromethylphenyl) benzene, 3,5-diaminobenzenetrifluoride, 4,4'-diamino-4"-(p-trifluoromethyl phenoxy) triphenylamine, and 4-[(4'-trifluoromethylphenoxy) phenyl]-2,6-bis(4"-aminophenyl)pyridine. Strong and flexible copolyimide films, produced by casting the polyamic acid solution followed by thermal imidization, exhibited great thermal stability and high mechanical properties. The polyimides had an ultraviolet-visible absorption cutoff at 330-340 nm and pretilt angles as high as 20degrees for nematic liquid crystals, making them great potential candidates for advanced liquid-crystal display applications.