Organosoluble and light-colored fluorinated semialicyclic polyimide derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride

摘要

In this study, the alicyclic dianhydrides 1,2,3,4- cyclobutanetetracarboxylic dianhydride (CBDA) was polymerized with seven kinds of fluorinated aromatic diamines, 2,2′-bis(trifluoromethyl)-4,4′- diaminobiphenyl (1), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (2), 1,4-bis(4-amino-2-trifluoromethylphenoxy)diphenyl (3), 1,4-bis(4-amino-2- trifluoromethylphenoxy) diphenyl ether (4), 2,2-bis[4-(4-amino-2- trifluoromethylphenoxy)phenyl]hexafluoropropane (5), 4,4′-bis(4-amino-2- trifluoromethylphenoxy)diphenyl sulfone (6), and 2,7-bis(4-amino-2- trifluoromethylphenoxy)naphthalene (7), via a two-step polycondensation procedure to prepare seven kinds of fluorinated semialicyclic polyimides (PI) PI-1 ～ PI-7. The structures of these polyimides were confirmed by infrared spectroscopy (IR). Solubility of the polyimides was tested in various organic solvents and their thermal properties were investigated by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Ultraviolet-visible spectra (UV-vis) and near infrared absorption spectra (NIR) were obtained to evaluate the optical properties of these polyimides. The obtained polyimides PI-1 ～ PI-7 displayed excellent solubility in a variety of organic solvents; they were readily soluble in amide-type polar solvent. These polyimide films exhibited good optical transparency in the visible light region (400-700 nm) with the transmittance higher than 80% at 450 nm, and these polyimide films showed little absorption at the optocommunication wavelengths of 1.30 and 1.55 μm. These polyimides showed good thermal stability with the 10% thermal decomposing temperatures higher than 443°C in nitrogen and the glass transition temperatures higher than 265°C. In addition, the effect of the structure of fluorinated diamines on the properties of polyimide films was also compared.