Synthesis and characterization of novel polyamides derived from 1,4-bis((4-amino-2-(trifluoromethyl)phenoxy)methyl)cyclohexane and aromatic dicarboxylic acids

Abstract

A new aromatic diamine with a trifluoromethyl pendent group, 1,4-bis((4-amino-2-(trifluoromethyl)phenoxy)methyl)cyclohexane, was successfully synthesized in two steps from 1,4-cyclohexanedimethanol and 2-chloro-5-nitrobenzotrifluoride as starting materials. And the newly obtained diamine with various aromatic dicarboxylic acids, including isophthalic acid (IPA), 2,2-bis(4-carboxy-phenyl)hexafluoropropane (6FA) and 4,4′-oxydibenzoic acid (OBA), were polymerized, respectively via the usual Yamazaki reaction to prepare a series of fluorinated polyamides. The resulting polymers had inherent viscosities ranging from 1.85 to 2.36 dL/g. All the polymers showed outstanding solubility and could be easily dissolved in amide-type polar aprotic solvents [e.g., N-methyl-2-pyrrolidone (NMP), DMAc, and DMF] and even dissolved in less polar solvents (e.g., pyridine, and tetrahydrofuran). These polymers could also be easily be cast into transparent, tough and flexible films with tensile strengths of 76.5–82.3 MPa, Young’s moduli of 1.64–1.85 GPa, and elongations at break of 10–12%. In addition, these polyamides films exhibited low dielectric constants of 2.37–2.53 at 100 MHz, low water absorptions in the range of 1.54–2.13%, and high transparency with an ultraviolet–visible absorption cut-off wavelength in the 326–333 nm range. Furthermore these polyamides still retained good thermal stability. These combined outstanding features make these obtained polyamides competitive for advanced microelectronic applications.