Synthesis and characterization of oxyethylene containing polyamide-imides

Two nonlinear dihydrazides, namely 1,2‐bis(3‐hydrazinocarbonylphenoxy)ethane and bis[2(3‐hydrazinocarbonylphenoxy)ethyl] ether, were synthesized by the acylation reaction of hydrazine hydrate with the corresponding aromatic esters and were characterized by IR, 13C‐NMR, and mass spectroscopy. These dihydrazides were each polycondensed with dianhydrides, benzophenonetetracarboxylic dianhydride (BTDA), and pyromellitic dianhydride (PMDA) to obtain poly(amic acid) with ηinh 0.60–0.85 dL/g in dimethylacetamide solution. These poly(amic acid)s were soluble in polar aprotic solvents like dimethylacetamide (DMAc), dimethyl formamide (DMF) and could be cast into transparent, tough, and flexible films that were cyclodehydrated to obtain amorphous, thermally stable polyamide‐imides. The polymers were characterized by IR spectroscopy, X‐ray diffraction, and thermogravimetric analysis.