Synthesis and characterization of novel aromatic polyimides from bis(4-amino-2-biphenyl)ether and aromatic tetracarboxylic dianhydrides

A new phenylated diamine, bis(4-amino-2-biphenyl)ether, was synthesized in five steps starting from 3-chloro-4-fluoronitrobenzene. New aromatic polyimides having phenyl groups at the 2- and T-positions of the diphenyl ether moiety were prepared from this diamine and various tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polymerization in NMP and subsequent thermal cyclic dehydration. The polyimides were characterized by differential scanning calorimetry (DSC), thermogravimetry, and dynamic mechanical analysis (DMA). Typical polyimides showed excellent thermal stability, and had glass transition temperature (T-g) above 250 degrees C. As for the series of polyimides prepared from tetracarboxylic anhydrides having linear phenylene moiety, the introduction of phenyl group at the 2- and T-positions of phenyl ether improved thermal and thermo-mechanical properties as well as the solubility of polymers.