Synthesis and properties of organosoluble polynaphthalimides based on 1,4,5,8-naphthalene tetracarboxylic dianhydride, 3,3-bis[4-(4- aminophenoxy)phenyl]phthalide, and various aromatic diamines

Two series of polynaphthalimides (PNIs), II and III, were prepared from 1,4,5,8-naphthalene tetracarboxylic dianhydride with the usual aromatic diamines (Ia–Ih) or Ia, which was used as a soluble modifying agent, and Ib–Ih via a one-stage process with high-temperature condensation. Series II and III had inherent viscosities of 0.57–1.34 and 1.15–1.63 dL/g, respectively. IIa and most of the III series were soluble in 1-methy-2-pyrrolidone and m-cresol at 5–10 wt % and afforded transparent and tough films by m-cresol solvent casting with a tensile strength in the range of 75–99 MPa. The glass-transition temperature and softening temperature of these PNIs were in the ranges of 360–404 and 188–241 °C, respectively, and the 10% weight loss temperatures were above 495 °C, with more than a 44% char yield at 800 °C in nitrogen. These PNI films had dielectric constants of 4.14–6.46 (1 MHz), with moisture absorption in the range of 0.87–1.91 wt %. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 940–948, 2006