The microstructures of a series of copolyimide films were characterized with different experimental methods such as density measurements, X-ray diffraction, ultraviolet-visible spectrophotometry, positron annihilation spectroscopy, and dynamic mechanical analysis. The experimental data were linked to the chemical structures of the polymers and especially the alicyclic and fluorinated monomers. Some analysis responses were directly dependent on the fluorine atoms and, therefore, did not provide clear information about the microstructures. The chain organization in the amorphous films appeared to be significantly dependent on the effect of the casting solvent. The influence diamine but was strongly attenuated with a fluorinated diamine. (C) 2003 Wiley Periodicals, Inc.