Synthesis and properties of aromatic polyamides based on a benzonorbornane bis(ether carboxylic acid)

A set of new aromatic polyamides containing ether and benzonorbornane units were synthesized by the direct phosphorylation polycondensation of 3,6-bis(4-carboxyphenoxy)benzonorbornane with various aromatic diamines. The polymers were produced in high yields and moderate to high inherent viscosities (0.64-1.70 dL/g). The polyamides derived from rigid diamines such as p-phenylenediamine and benzidine were semicrystalline and insoluble in organic solvents. The other polyamides were amorphous and organosoluble and afforded flexible and tough films via solution casting. These films exhibited good mechanical properties, with tensile strengths of 95-101 MPa, elongations at break of 13-25%, and initial moduli of 1.97-2.33 GPa. The amorphous polyamides showed glass-transition temperatures between 176 and 212 degreesC (by differential scanning calorimetry) and softening temperatures between 194 and 213 degreesC (by thermomechanical analysis). Most of the polymers did not show significant weight loss before 450 degreesC in nitrogen or in air. Some properties of these polyamides were also compared with those of homologous counterparts without the pendent norbornane groups. (C) 2002 Wiley Periodicals, Inc.