A novel fluorinated diamine monomer, 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di-tert-butylbenzene (2), was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride and 2,5-di-tert-butylhydroquinone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Fluorinated polyimides (5a-5f) were synthesized from diamine 2 and various aromatic dianhydrides (3a-3f) via thermal or chemical imidization. These polymers had inherent viscosities of 0.77-1.01 dL/g. The 5 series polyimides were soluble in N-methyl-2-pyrrolidone, NN-dimethylacetamide, and N,N-dimethylformamide and were even soluble in dioxane, tetrahydrofuran, and dichloromethane. 5(C) showed cutoff wavelengths between 363 and 404 nm and yellowness index (b*) values of 6.5-40.2. The polyimide films had tensile strengths of 93-114 MPa, elongations to break of 9-12%, and initial moduli of 1.7-2.1 GPa. The glass-transition temperatures were 255-288 degreesC. The temperatures of 10% weight loss were all above 460 degreesC in air or nitrogen atmospheres. In comparison with a nonfluorinated polyimide series based on 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, the 5 series showed better solubility and lower color intensity, dielectric constants, and moisture absorption. (C) 2004 Wiley Periodicals, Inc.