Scalings of fluorine-containing polyimides in cyclopentanone

Eight 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-4,4'-diam ino-3,3'-dimethylbiphenyl (6FDA-OTOL) fractions and seven 2,2'-bis[4-(3,4-d icarboxyphenoxy) phenyl] propane dianhydride-4,4'-diamino-3,3'-dimethylbiph enyl (BISADA-OTOL) fractions in cyclopentanone at 30 degrees C were charact erized by a combination of viscometry and static and dynamic laser light sc attering (LLS). In static LLS, the angular dependence of the absolute scatt ered intensity led to the weight-average molar mass (M-w), the z-average ro ot mean square radius of gyration, and the second virial coefficient. In dy namic LLS, the Laplace inversion of each measured intensity-intensity time correlation function resulted in a corresponding translational diffusion co efficient distribution [G(D)]. The scalings of [D] (cm(2)/s) = 8.13 x 10(-5 ) M-w(-0.47) and [eta] (dL/g) = 2.36 x 10(-3) M-w(0.54) for 6FDA-OTOL and [ D] (cm(2)/s) = 3.02 x 10(-4) M-w(-0.60) and [eta] (dL/g) = 2.32 x 10(-3) M- w(0.53) for BISADA-OTOL were established. With these scalings, we successfu lly converted each G(D) value into a corresponding molar mass distribution. At 30 degrees C, cyclopentanone is a good solvent for BISADA-OTOL but a po or solvent for 6FDA-OTOL; this can be attributed to an ether linkage in BIS ADA-OTOL. Therefore, BISADA-OTOL has a more extended chain conformation tha n 6FDA-OTOL in cyclopentanone. (C) 2000 John Wiley & Sons, Inc.