Scalings of fluorine-containing polyimides in cyclopentanone

Abstract

Eight 2,29-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-4,49- diamino-3,39-dimethylbiphenyl (6FDA-OTOL) fractions and seven 2,29-bis(4-(3,4-dicar- boxyphenoxy) phenyl) propane dianhydride-4,49-diamino-3,39-dimethylbiphenyl (BISADA-OTOL) fractions in cyclopentanone at 30 °C were characterized by a combi- nation of viscometry and static and dynamic laser light scattering (LLS). In static LLS, the angular dependence of the absolute scattered intensity led to the weight-average molar mass (Mw), the z-average root mean square radius of gyration, and the second virial coefficient. In dynamic LLS, the Laplace inversion of each measured intensity- intensity time correlation function resulted in a corresponding translational diffusion coefficient distribution (G(D)). The scalings of ^D& (cm 2 /s) 5 8.13 3 10 25 Mw 20.47 and (h) (dL/g) 5 2.36 3 10 23 Mw 0.54 for 6FDA-OTOL and ^D& (cm 2 /s) 5 3.02 3 10 24 Mw 20.60 and (h) (dL/g) 5 2.32 3 10 23 Mw 0.53 for BISADA-OTOL were established. With these scalings, we successfully converted each G(D) value into a corresponding molar mass distribution. At 30 °C, cyclopentanone is a good solvent for BISADA-OTOL but a poor solvent for 6FDA-OTOL; this can be attributed to an ether linkage in BISADA-OTOL. Therefore, BISADA-OTOL has a more extended chain conformation than 6FDA-OTOL in cyclopentanone. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2077-2080,