A series of fluorinated poly(amide imide)s were prepared from 1,4-bis(2'-trifluoromethyl-4'-trimellitimidophenoxy)benzene and various aromatic diamines [3,3',5,5'-tetramethyl-4,4'-diaminediphenylmethane, alpha,alpha-bis(4-amino-3,5-dimethyl phenyl)-3'-trifluoromethylphenylmethane, 1,4-bis(4-amino-2'-trifluoromethylphenoxy)benzene, 4-(3'-trifluoromethylphenyl)-2,6-bis(3'-aminophenyl)pyridine, and 1,1-bis(4'-aminophenyl)-1-(3'-trifluoromethylphenyl)-2,2,2-trifluoroethane]. The fluorinated poly(amide imide)s, prepared by a one-step polycondensation procedure, had good solubility both in strong aprotic solvents, such as N-methyl-2-pyrrolidinone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and cyclopentanone, and in common organic solvents, such as tetrahydrofuran and m-cresol. Strong and flexible polymer films with tensile strengths of 84-99 MPa and ultimate elongation values of 6-9% were prepared by the casting of polymer solutions onto glass substrates, followed by thermal baking. The poly(amide imide) films exhibited high thermal stability, with glass-transition temperatures of 257-266 degreesC and initial thermal decomposition temperatures of greater than 540 degreesC. The polymer films also had good dielectric properties, with dielectric constants of 3.26-3.52 and dissipation factors of 3.0-7.7 X 10(-3), and acceptable electrical insulating properties. The balance of excellent solubility and thermal stability associated with good mechanical and electrical properties made the poly(amide imide)s potential candidates for practical applications in the microelectronics industry and other related fields. (C) 2003 Wiley Periodicals, Inc.