AbstractThe polymerization of 4‐chloroformylphthalic anhydride with 4,4′‐diaminodiphenyl ether was investigated under a variety of reaction conditions. Both interfacial and solution techniques were used, with the latter method yielding the highest molecular weight polymer. Synthesis of high molecular weight polyamide‐imides requires the use of pure monomers, exclusion of moisture, and proper stoichiometry. Molecular weight control can be achieved by the addition of either aniline or phthalic anhydride. Heating of the resin solution for 1 hr at temperatures ≥ 50°C results in a large decrease in inherent viscosity as well as in the polymer properties. Tertiary amines such as triethylamine, when added to the precursor solution, markedly influence the viscosity of
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