A new fluorinated diamine, 2,2 -thio-bis-[4-methyl(2-trifluoromethyl)4-aminophenoxy) phenyl ether] (DA), was successfully synthesized by refluxing dibenzosulfide (DH) and 2-chloro-5-benzotrifluoride 2-chloro-5-nitrobenzotrifluoride in the presence of potassium carbonate, followed by catalytic reduction with zinc/ammonium chloride. Then, a series of organic-soluble polyamides (PAa-PAg) bearing flexible ether and sulfide links, and a electron-withdrawing trifluoromethyl group were synthesized from diamine (DA) with various aromatic diacids (a-g) via direct polycondensation with triphenyl phosphate and pyridine. The polyamides were obtained in quantitative yields and possessed inherent viscosities in the range of 0.35-0.86 dl/g. All the polymers were noncrystalline, showed outstanding solubility and could be easily dissolved in amide-type polar aprotic solvents (e.g., N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and N,N-dimethylformamide) and even dissolved in less polar solvents (e.g., pyridine and tetrahydrofuran). They were in useful levels of thermal stability: 10% weight loss in nitrogen atmosphere was in the range of 375-480 • C, depending on the structure of the polymer main chain. The polymers showed glass transition temperatures between 160 and 210 • C. © Koninklijke Brill NV, Leiden, 2009