Highly organosoluble and transparent polyamides containing cyclohexane and trifluoromethyl moieties: Synthesis and characterization

New aromatic diamine with cyclohexane moiety substituted with trifluoromethyl group in the side chain, 4,4'-(cyclohexane-1,4-diylbis(oxy))bis(3-(trifluoromethyl)aniline) (2), was successfully synthesized through the Williamson reaction of 1,4-cyclohexanediol and 2-chloro-5-nitrobenzotrifluoride, to yield the intermediate dinitro compound 1, followed by catalytic reduction with hydrazine and Pd/C to afford the diamine 2. This diamine monomer leads to a series of organic-soluble polyamides (4a-d) when reacted with different commercially available aromatic diacids (a-d) via a direct polycondensation with triphenyl phosphite and pyridine. The resulting polymers had inherent viscosities ranging from 0.89 to 1.29 dl/g. All the polymers showed outstanding solubility and could be easily dissolved in amide-type polar aprotic solvents and even dissolved in less polar solvents. All the polymers formed transparent, strong, and flexible films with tensile strengths of 54-68 MPa, Young's moduli of 1.6-1.9 GPa, and elongations at break of 13.3-15.5%. These polyamide films have low dielectric constants of 2.15-2.88 at 1 MHz and low water absorptions of 1.96-2.84%. Wide-angle X-ray diffraction measurements revealed that these polyamides were amorphous in nature.