The poly(urea-imide) copolymers with inherent viscosity of 0.81-1.08 dL/g were synthesized by reacting aryl ether diamine or its polyurea prepolymer with various diisocyanate-terminated polyimide prepolymers. The aryl ether diamine was obtained by first nucleophilic substitution of phenolphthalein with p-chloronitrobenzene in the presence of anhydrous potassium carbonate to form a dinitro aryl ether, and then further hydrogenated to diamine. The polyimide prepolymers were prepared by using 4,4Π-diphenylmethane diisocyanate to react with pyromellitic dianhydride, 3,3Π,4,4Π-benzophenonetetracarboxylic dianhydride, or 3,3Π,4,4Π-sulfonyldiphthalic anhydride by using the direct one-pot method to improve their solubility, but without sacrificing thermal property. These copolymers are amorphous and readily soluble in a wide range of organic solvents such as N-methyl-2-pyrrolidone, dimethylimidazole, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, m-cresol, and sulfolane. All the poly(urea-imides) have glass transition temperatures in the range of 205-240Β°C and show a 10 wt % loss at 326 -352Β°C in nitrogen and 324 -350Β°C in air. The tensile strength, elongation at break, and initial modulus of these copolymer films range from 42 to 79 MPa, 5 to 16%, and 1.23 to 2.02 GPa, respectively.