Synthesis and properties of alternating copolyamide-imides based on 2,6-bis(4-aminophenoxy)naphthalene and comparison with its related isomeric polymers

A series of novel polyamide-imides III containing 2,6-bis(phenoxy)naphthale ne units were synthesized by 2,6-bis(4-aminophenoxy)naphthalene and various bis(trimellitimide)s in N-methyl-2-pyrrolidone (NMP) using triphenyl phosp hite and pyridine as condensing agents through direct polycondensation. The polymers were obtained in quantitative yield with inherent viscosities up to 1.53 dL/g. Most of the polymers showed good solubility in NMP, N,N-dimet hylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide and could be so lution-cast into transparent, flexible, and tough films. The films had tens ile strengths of 84-111 MPa, elongations at break of 8-33%, and initial mod uli of 2.2-2.8 GPa. Wide-angle X-ray diffraction revealed that most polymer s III were amorphous. The glass-transition temperatures of some of the poly mers could be determined by differential scanning calorimetry traces, recor ded at 247-290 degreesC. The polyamide-imides exhibited excellent thermal s tabilities and had 10% weight loss at temperatures in the range of 501-575 degreesC under nitrogen atmosphere. They left more than 57% residue even at 800 degreesC in nitrogen. A comparative study of some corresponding polyam ide-imides is also presented. (C) 2001 John Wiley & Sons, Inc.