Process for making polyetherimides

A process for making polyetherimide, which comprises:

• (a) reacting an aromatic bis(ether anhydride) of the formula ##STR9## with an organic diamine of the formula
• H.sub.2 N-R-NH.sub.2
• in an inert solvent under polyetherimide-forming conditions, which include a reaction temperature of from about 40.degree. C. to about 200.degree. C., to form a prepolymer-solvent mixture;
• (b) forming a thin film of the prepolymer-solvent mixture under solvent-volatilizing conditions, which includes a temperature of from about 200.degree. C. to about 450.degree. C., to effect substantially complete removal of solvent and water of reaction from said mixture to form a prepolymer;
• and
• (c) heating the prepolymer to a temperature above the glass transition temperature of the final polyetherimide product and less than about 450.degree. C. to form the polyetherimide;
• wherein, Z is a member selected from the class consisting of (A) divalent organic radicals having the following formulas ##STR10## and (B) divalent organic radicals of the general formula ##STR11## wherein X is a member selected from the group consisting of divalent radicals of the formulas ##STR12## where y is an integer from 1 to about 5;
• and R is a divalent organic radical selected from the group consisting of aromatic hydrocarbon radicals having from 6 to about 20 carbon atoms and halogenated derivatives thereof, alkylene radicals having from 2 to about 20 carbon atoms, cycloalkylene radicals having from 3 to about 20 carbon atoms, from C.sub.2 to about C.sub.8 alkylene terminated polydiorganosiloxane, and divalent radicals of the general formula ##STR13## where Q is a member selected from the class consisting of ##STR14## and x is an integer from 1 to about 5.