TECHNOLOGY FOCUS - POLYMERS - Preferred Unit: Unit (II) is preferably of formula (III). The polyimide further consists of a repeating unit of formula (IV).B'=tetravalent aliphatic group. EXAMPLE - 3.2023 g 2,2'-Bis(trifluoromethyl)benzidine, 1.75 mL tetrahydrofuran (THF), and 3.3 mL pyridine solution were added to a solution obtained by dissolving 3.8023 g 4-nitrobenzene carboxylic acid chloride in 6.26 mL THF under ice bath. A large amount of yellow-white color precipitation was generated. The obtained precipitate was filtered after leaving to stand for 12 hours, washed with THF and ion-exchange, and dried under reduced pressure at 100 degrees C for 12 hours to obtain 5.9216 g 4-nitro-N-(4-(4-((4-nitrobenzene)amido)-2-(trifluoromethyl)phenyl)-3-(trifluoromethyl)phenyl)benzamide with a yield of 95.7%. 9.241 g 4-nitro-N-(4-(4-((4-nitrobenzene)amido)-2-(trifluoromethyl)phenyl)-3-(trifluoromethyl)phenyl)benzamide and 0.9279 g palladium/carbon were dissolved and dispersed in 120 mL ethanol. Hydrogen gas was bubbled at 80 degrees C in the obtained solution and reaction was carried out for 7 hours. The reaction end point was confirmed with thin layer chromatography. Hot-filtration of the reaction mixture was carried out after completion of reaction, and the formed white precipitate was dripped in water. The obtained powder was fractionated after 12-hour stirring, washed with water, and dried under reduced pressure at 100 degrees C for 12 hours, to obtain 7.9811 g crude 4-amino-N-(4-(4-((4-aminobenzene)amido)-2-(trifluoromethyl)phenyl)-3-(trifluoromethyl)phenyl)benzamide with a yield of 95.6%. 0.5012 g Crude product was dissolved in 40 mL ethanol and 10 mL ion-exchange water at 65 degrees C and hot-filtered. 20 mL Ion-exchange water was added to the filtrate and recrystallized to obtain 0.4212 g purified product by cooling. The compound had a melting point of 317 degrees C. 1.6754 g 4-amino-N-(4-(4-((4-aminobenzene)amido)-2-(trifluoromethyl)phenyl)-3-(trifluoromethyl)phenyl)benzamide was dissolved in 5.4784 g N-methylpyrrolidone. 0.6725 g 1S,2S,4R,5R-cyclohexane tetracarboxylic dianhydride was added to the obtained solution and stirred at room temperature for 7 hours. A mixed solvent of 3.0627 g acetic anhydride and 1.1865 g pyridine was slowly dripped at room temperature and stirred for 24 hours. The obtained solution was added to a lot of methanol and product was precipitated. The obtained white precipitate was washed with methanol and vacuum-dried to obtain polyimide powder. A film of thickness 10 microns formed using the polyimide had a glass transition temperature of 370 degrees C, a thermal decomposition temperature of 426 degrees C, a linear thermal expansion coefficient of 24 ppm/K, a light transmittance of 75.9% at 400 nm, an average elongation of 12%, a tensile elasticity modulus of 3.4 GPa, a breaking strength of 0.12 GPa, and a refractive index of 1.5906.