Synthesis of new soluble aromatic poly(amide imide)s from unsymmetrical extended diamine containing phthalazinone moiety

The preparation of a new unsymmetrical kink non-coplanar heterocyclic diamine, 1,2-dihydro-2-(4-aminophenyl)-4-[4-(3-phenyl-4-aminophenoxy)phenyl]-(2H)phthalazin-1-one (3), from a readily available unsymmetrical phthalazinone bisphenol-like (1) was described. The diamine can be directly polymerized with various aromatic bis(trimellitimide)s (4a–e) by using triphenyl phosphite and pyridine as condensing agents to give a series of new aromatic poly(amide imides) (5a–e) containing the kink non-coplanar phthalazinone heterocyclic units with inherent viscosities of 0.57–1.06 dL/g. The polymers were readily soluble in a variety of solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidinone, and even in pyridine and m-cresol and could be cast to form flexible and tough films. The glass transition temperatures were in the range of 315–340°C, and the temperatures for 5% weight loss in nitrogen were in the range of 487–512°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1516–1520, 2004