Polycondensation stoichiometry control

Abstract

A method of making a polyetherimide including: setting a target range for the anhydride-amine stoichiometry in a reaction mixture; combining a solvent, a diamine, a bis(ether anhydride), and an optional end capping agent to form the reaction mixture wherein the reaction mixture has a polyamic acid content; analyzing the amine and anhydride end group content of the reaction mixture using near infrared vibrational spectroscopy; calculating the anhydride-amine stoichiometry; comparing the calculated anhydride-amine stoichiometry to the target stoichiometry, and, when necessary, adjusting the concentration of bis(ether anhydride) or diamine based on the comparison of the calculated anhydride-amine stoichiometry to the target stoichiometry.

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