Polymer, Vol.46, No.15, 5797-5807, 2005
Colorless polyimides from 2,3,3',4'-biphenyltetracarboxylic dianhydride (alpha-BPDA) and various aromatic bis(ether amine)s bearing pendent trifluoromethyl groups
A series of organosoluble and light-colored polyimides (III) was prepared from 2,3,3',4-biphenyltetracarboxylic dianhydride (alpha-BPDA) with various fluorinated aromatic bis(ether amine)s via two-step method with thermal or chemical imidization of poly(amic acid)s yielded polyimides. The III series had inherent viscosity of 0.74-1.01 dl/g and showed excellent solubility in a variety of organic solvents. They were soluble in the amide polar solvent, ether-type solvent, and chlorinated solvent. These polyimide films also showed a high optical transparency and less color intensity, with an ultraviolet-visible absorption edge of 369-382 nm and low b* values (a yellowness index) of 5.0-11.7. Glass-transition temperature of the III series was recorded at 244-319 degrees C and higher than the isomeric polyimides V series. Compared with the nonfluorinated polyimides IV, the III series showed lighter-colored and lower dielectric constants and moisture absorptions. The good tensile properties and excellent thermal properties of the III series were also observed. (c) 2005 Elsevier Ltd. All rights reserved.
Keywords:2,3,3 ',4 '-biphenyltetracarboxylic dianhydride;fluorine-containing polyimide;bis(ether amine)