In this study, the alicyclic dianhydrides 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) was polymerized with seven kinds of fluorinated aromatic diamines, 2,2 0 -bis(trifluoromethyl)-4,4 0 -diaminobiphenyl (1), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (2), 1,4-bis(4-amino-2-trifluoromethylphenoxy)diphenyl (3), 1,4bis(4-amino-2-trifluoromethylphenoxy) diphenyl ether (4), 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane (5), 4,4 0 -bis(4-amino-2-trifluoromethylphenoxy)diphenyl sulfone (6), and 2,7-bis(4-amino-2trifluoromethylphenoxy)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 lm. 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.
• C for 1 h. The average molecular weights of the products obtained using various rare earth catalysts were in order Nd > La > Sm > Gd, which shows that the light rare earths were more favorable for higher molecular weight products than the heavy ones. According to the polymerization features, a cationic equilibrium reaction mechanism is proposed.
The alicyclic dianhydrides 1,2,3,4-cyclobutanetetracarboxylic dianhydride(CBDA) was polymerized with four kinds of fluorinated aromatic diamine, 2,2’-bis(trifluoromethyl)-4,4’- diaminobiphenyl(TFDB), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene(6FAPB), 1,4-bis(4- amino-2-trifluoromethylphenoxy) diphenyl ether (6FAPE) and 1,4-bis(4-amino-2-trifluoromethyl- phenoxy)diphenyl(6FBAB) respectively, via a two-step polycondensation procedure to prepare four series of fluorinated polyimides(PIs) derived from CBDA. The obtained PIs displayed excellent solubility in aprotic polar solvents, such as NMP, DMAc, DMF and DMSO. These PIs showed good thermal stability with the 10% thermal decomposing temperatures higher than 457 in nitrogen and the glass transition temperatures higher than 267 . In addition, the PI films exhibited good optical transparency in the visible light region(400-700nm) with the transmittance higher than 80% at 450nm, and the PI films showed little absorption at the optocommunication wavelengths of 1.30µm and 1.55µm.
In this paper, we mainly investigated the properties of fluorinated polyimides film materials. Two aromatic dianhydrides, PMDA and ODPA were poly-condensed with four fluorinated diamines to prepare fluorinated polyimides by the two-step thermal imidization process. The properties of these polyimides were characterized by IR, TGA and UV-vis instrument. The organosolublility of these polyimides was tested in various organic solvents, such as NMP, DMF, DMAc. In addition, the effect of monomers’ molecular structure on the optical, soluble and thermal properties of these polyimides was also studied.
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