Trimellitic anhydride was reacted with 4,4'diaminodiphenyl ether in a mixture of acetic acid and pyridine (3 : 2) at room temperature and was refluxed at 90-100degreesC, and NN'-(4,4'-diphenylether) bistrimellitimide (3) was obtained in a quantitative yield. 3 was converted into N,N'-(4,4'-diphenylether) bistrimellitimide diacid chloride (4) by a reaction with thionyl chloride. Then, six new poly(amide imide)s were synthesized under microwave irradiation with a domestic microwave oven through the polycondensation reactions of 4 with six different derivatives of 5,5-disubstituted hydantoin in the presence of a small amount of a polar organic medium such as 0-cresol. The polycondensation proceeded rapidly and was completed within 7-10 min, producing a series of new poly(amide imide)s in high yields with inherent viscosities of 0.27-0.66 dL/g. The resulting poly(amide imide)s were characterized by elemental analysis, viscosity measurements, differential scanning calorimetry, thermogravimetric analysis, derivative thermogravimetry, solubility testing, and Fourier transform infrared spectroscopy. All the polymers were soluble at room temperature in polar solvents such as NN-dimethylacetamide, NN-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, and N-methyl-2-pyrrolidone. (C) 2004 Wiley Periodicals, Inc.