Synthesis and characterization of polyamides and poly(amide–imide)s derived from 2,2-bis(4-aminophenoxy) benzonitrile

A series of polyamides and poly(amide–imide)s were prepared by the direct poly-condensation of 2,2-bis(4-aminophenoxy) benzonitrile [4-APBN] with aromatic dicarboxylic acids and bis(carboxyphthalimide)s in N-methyl-2-pyrrolidone [NMP] with triphenyl phosphite and pyridine as condensing agents. The synthesis of 4-APBN involves a nucleophilic displacement reaction in dipolar aprotic solvent with the alkali metal salt of p-aminophenol and an activated aromatic dichloro compound. Bis(carboxyphthalimide)s were prepared by condensation of 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylether, 4,4′-diaminodiphenylmethane, 3,3′-diaminobenzophenone, and trimellitic anhydride at a 1:2 molar ratio. The inherent viscosities of the resulting polymers were found to be in the range of 0.31–0.93 dl/g and glass transition temperatures between 235 and 298 °C. All polymers were soluble in aprotic polar solvents such as dimethylsulfoxide and NMP. The results of thermogravimetry revealed that all the polymers showed no significant weight loss before 400 °C. Wide-angle X-ray diffractograms revealed that all polymers were found to be amorphous except for the polyamide derived from isophthalic acid and polyamide–imides derived from diaminodiphenylether and diaminobenzophenone based bis(carboxyphthalimide)s.