Synthesis and properties of novel soluble and high Tg poly(ether imide)s from diamine containing 4,5-diazafluorene and trifluoromethyl units

The synthesis and properties of soluble, high T-g and transparent aromatic polyimides containing 4,5-diazafluorene and trifluoromethyl units in the polymer backbone on the basis of a novel diamine monomer, 9,9-di[4-(4-amino-2-trifluoromethyl phenoxy)phenylene]-4,5-diazafluorene, are described. Incorporation of 4,5-diazafluorene and trifluoromethyl groups into rigid polyimides improves their solubility and transparency without decreasing their physical properties. All of the thermal imidization polyimides are soluble at room temperature in aprotic and protic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, pyridine and m-cresol and can be solution cast into transparent, flexible and tough films. These films have a UV-visible absorption cutoff wavelength at 386-407nm and light transparencies of 73%-84% at a wavelength of 550nm. In addition, the polymers exhibit high thermal stability with a glass transition temperature (T-g) of 305 to 362 degrees C and 5% weight loss at temperatures ranging from 525 to 543 degrees C in nitrogen and from 521 to 538 degrees C in air. The polyimide films possess tensile strengths in the range 79-113MPa, a tensile modulus of 1.75-2.10GPa and elongations at break of 7%-16%. (c) 2014 Society of Chemical Industry