New poly(amide-imide)s syntheses. VIII. Preparation and properties of poly (amide-imide)s derived from 2,3-bis(4-aminophenoxy)naphthalene, trimellitic anhydride, and various aromatic diamines

The new polymer‐forming diimide‐diacid, 2,3‐bis(4‐trimellitimidophenoxy) naphthalene (I), was readily obtained by the condensation reaction of 2,3‐bis (4‐aminophenoxy) naphthalene with trimellitic anhydride. A series of novel aromatic poly (amide‐imide)s were prepared by the direct polycondensation of diimide‐diacid I with various aromatic diamines using triphenyl phosphite in N‐methyl‐2‐pyrrolidone (NMP)/pyridine solution containing dissolved calcium chloride. The resultant polymers have inherent viscosities in the range of 0.65–1.02 dL/g at 30°C in N, N‐dimethylacetamide. These polymers were readily soluble in various organic solvents and could be cast into transparent, tough, and flexible films. Their casting films showed tensile strength at break up to 86 MPa, elongation to break of 5–9%, and initial moduli up to 2.35 GPa. The wide‐angle X‐ray diffraction revealed that those polymers containing p‐phenylene or p‐oxyphenylene group are partially crystalline, and the other polymers are evidenced as amorphous patterns. These polymers show a glass transition in the range of 213–290°C in their differential scanning calorimetry (DSC) traces. The thermal stability of the polymers was evaluated by thermogravimetry analysis, which showed the 10% weight‐loss temperatures in the range of 508–565°C in nitrogen and 480–529°C in air atmosphere. © 1994 John Wiley & Sons, Inc.