Synthesis and properties ofortho-linked aromatic polyimides based on 1,2-bis(4-aminophenoxy)-4-tert-butylbenzene

A bis(ether amine) containing the ortho-substituted phenylene unit and pendant tert-butyl group, 1,2-bis(4-aminophenoxy)-4-tert-butylbenzene, was synthesized and used as a monomer to prepare polyimides with six commercial dianhydrides via a conventional two-stage procedure. The intermediate poly(amic acid)s had inherent viscosities of 0.78–1.44 dL/g, and most of them could be thermally converted into transparent, flexible, and tough polyimide films. The inherent viscosities of the resulting polyimides were in the range of 0.46–0.87 dL/g. All polyimides were noncrystalline, and most of them showed excellent solubility in polar organic solvents. The glass-transition temperatures of these polyimides were in the range of 222–259 °C in differential scanning calorimetry and 212–282 °C in thermomechanicl analysis. These polyimides showed no appreciable decomposition up to 500 °C in thermogravimetric analysis in air or nitrogen. A comparative study of the properties with the corresponding polyimides without pendant tert-butyl groups derived from 1,2-bis(4-aminophenoxy)benzene is also presented.