Polyetherimide preparation method including addition of macrocyclic polyetherimide oligomers

Abstract

Macrocyclic polyether oligomers, preferably as mixtures of oligomers of different degrees of polymerization, are incorporated in a direct displacement reaction mixture for the formation of polyetherimides, said reaction mixture comprising at least one alkali metal salt of a dihydroxy-substituted aromatic hydrocarbon and at least one bis(halo- or nitrophthalimide). The macrocyclic oligomers can be isolated from an earlier-prepared linear polyetherimide composition. Their incorporation in the reaction mixture does not increase the proportion of oligomers in the polyetherimide product.

Dependencies are inferred from the claim text.