Soluble copoly(pyridine ether imide)s derived from 6FDA, 1,4-bis(4-amino-2-trifluromethylphenoxy)benzene, and 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine

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A series of new fluorinated copoly(pyridine ether imide)s were prepared by thermal imidization of polyamide acid derived from 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (BATB), 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine (TFMPBPP), and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) with various mole ratios of BATB and TFMPBPP ranged from 80/20 to 20/80. All copolyimides were amorphous and had excellent solubility in organic solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylformamide (DMF) at room temperature and displayed good thermal properties with glass transition temperature ( Tg) of 272°C–338°C, 5% weight loss temperature of 520°C–540°C, and the residue of 44–56% at 750°C in nitrogen. Meanwhile, the Tg of the copolymers increased with an increase in the TFMPBPP component. Tough and flexible copolyimide films also exhibited outstanding mechanical properties with tensile strengths of 107.2–153.2 MPa, tensile moduli of 1.4–1.8 GPa, and elongations at break of 13.2–19.6%, low dielectric constants of 2.76–2.92 (1 MHz), and water uptake 0.32–0.62% as well as high optical transparency with the UV cutoff wavelength in the 371–386 nm range and the wavelength of 80% transparency in the range 459–498 nm.