New soluble aromatic polyamides from non-symmetrical extended diacid containing a phthalazinone moiety

A new monomer diacid, 1,2-dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxylphenoxy)phenyl](2H)phthalazin-1-one (3), was synthesized through the aromatic nucleophilic substitution reaction of a readily available unsymmetrical phthalazinone bisphenol-like (1) with p-chlorobenzonitrile in presence of potassium carbonate in N,N-dimethylacetamide and alkaline hydrolysis. The diacid can be direct polymerized with various aromatic diamines (4a-d) using triphenyl phosphite and pyridine as condensing agents to give a series of new aromatic poly(ether amide)s (5a-d) containing the kink non-coplanar heterocyclic units with inherent viscosities of 1.26-1.53 dl/g. The polymers were readily soluble in a variety of solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidinone (NMP), even in m-cresol and pyridine (Py) and partly soluble in chloroform at room temperature and afforded transparent. flexible and tough films by solution casting. The glass transition temperatures (T-g) were in the range of 291-329degreesC, and the temperatures for 5% weight loss in nitrogen were in the range of 445-520degreesC.