Synthesis and properties of new pyridine-bridged poly(ether-imide)s based on 4-(4-trifluoromethylphenyl)-2,6-bis[4-(4-aminophenoxy)phenyl]pyridine

A novel pyridine-containing aromatic diamine monomer, 4-(4-trifluoromethylphenyl)-2,6-bis[4-(4-aminophenoxy)phenyl]pyridine (FAPP), was synthesized via the modified Chichibabin pyridine synthesis of 4-(4-nitrophenoxy)-acetophenone with 4-trifluoromethyl-benzaldehyde, followed by a catalytic reduction. A series of fluorinated pyridine-bridged aromatic poly(ether-imide)s were prepared from the resulting diamine monomer with various aromatic dianhydrides via a conventional two-step process. The resulting polyimides exhibited good solubility in aprotic amide solvents and m-cresol, such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol, etc., which possessed the inherent viscosities of 0.76–0.91 dL/g. Strong and flexible poly(ether-imide) films were obtained, which showed excellent thermal properties with the glass transition temperatures of 268–353 °C, the temperature at 5% weight loss of 547–595 °C, and the residue at 700 °C of 65–74% in nitrogen, good mechanical properties with the tensile strengths of 87.6–104.2 MPa and elongations at breakage of 8.9–12.6%, and good optical transparency with the cut-off wavelengths of 357–380 nm, as well as low dielectric constants in the range of 2.49–3.04 at 1 MHz and low water uptake 0.43–0.69%. Furthermore, the resulted polyimides derived from FAPP were compared with non-fluorinated analogous polyimides and fluorinated analogous polyimides with trifluoromethyl groups in different positions, and the effects of substituents were also investigated and discussed.

A series of fluorinated pyridine-bridged aromatic poly(ether-imide)s were prepared from a novel pyridine-containing aromatic diamine monomer and the resulting polyimides exhibited good solubility in organic solvents, excellent thermal properties, and good mechanical properties, as well as low dielectric constants and good optical transparency. The effects of fluorine substituents were discussed.Figure optionsDownload as PowerPoint slide