Optically high transparency and light color of organosoluble polyamides containing trifluoromethyl and kink diphenylmethylene linkage

New polyamides were prepared directly from a diamine, bis[4-(2-trifluoromethyl 4-aminophenoxy)phenyl] diphenylmethane, containing an electron-withdrawing trifluoromethyl group and a kink diphenylmethylene linkage with various aromatic dicarboxylic acids having inherent viscosities ranging from 0.66 to 0.83 dL g(-1). All the polyamides 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, cyclohexanone, and tetrahydrofuran). The dielectric constants of the polyamide films were 3.37-3.87 (100 KHz) and decreased with an increase in the frequency, which ranged from 1 Hz to 100 KHz. A low coefficient of thermal expansion for the polyamides was observed in the range of 54-78 ppm/degrees C (by thermomechanical analysis). These polyamides showed excellent thermal stability, and the 10% weight loss temperatures were in the range of 484-507 degrees C in an atmosphere of nitrogen. The polymers had an initial modulus of 1.8-2.2 GPa. The polyamides with kink and electron-withdrawing trifluoromethyl units afforded light-color polymer films with high transmittance in the visible region (400-700 nm), and their cutoff wavelength was lower than 362 nm. (c) 2005 Wiley Periodicals, Inc.