| Abstract: | A new aromatic asymmetrical ether diamine, 5‐(4‐aminophenoxy)‐1‐naphthylamine, was synthesized through the nucleophilic displacement of 4‐chloronitrobenzene with the potassium phenolate of 5‐amino‐1‐naphthol in dimethylformamide, followed by hydrazine palladium‐catalyzed reduction. A series of novel aromatic polyimides containing asymmetrical diaryl ether segments were prepared from the diamine with various aromatic dianhydrides via a conventional two‐step thermal or chemical imidization method. The poly(amic acid) precursors had inherent viscosities of 1.21–1.99 dL/g, and all of them could be cast and thermally converted into transparent, flexible, and tough polyimide films. The polyimides derived from less stiff dianhydrides generally displayed higher solubility. The glass‐transition temperatures of these polyimides were recorded between 307 and 336 °C by differential scanning calorimetry, and the softening temperatures of the polymer films were 299–344 °C according to thermomechanical analysis. The polyimides showed insignificant decomposition before 520 °C in air or nitrogen. For a comparative study, two series of analogous polyimides based on symmetrical diamines such as 1,5‐diaminonaphthalene and 1,5‐bis(4‐aminophenoxy)naphthalene were also prepared and characterized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 331–341, 2005 |
