Synthesis and properties of poly(ether imide)s derived from dihydroxynaphthalenes

Poly(ether imide)s were synthesized from bis(ether anhydride)s derived from 1,5-, 2,3-, 2,6- and 2,7-dihydroxynaphthalenes and various aromatic diamines using a two-stage solution process, normally with chemical imidization. During the synthesis of polymers from the bis(ether anhydride) from 2,3-dihydroxynaphthalene and 4,4'-oxydianiline (4,4'-ODA), by both chemical and thermal imidization, small proportions of a relatively insoluble, infusible, crystalline solid were produced. It is proposed that this product is a cyclic oligomer. Solubilities of the polymers were assessed and, where sufficiently soluble, molecular weights were determined by gel permeation chromatography. Apart from polymers based on 2,3-naphthalene units, the polymers had limited solubilities. Glass-transition temperatures were determined; all were in excess of 220 degrees C, some were in excess of 300 degrees C. Several poly(ether imide)s based on ODA, were found to be thermally stable to 590 degrees C. Polymers based on the bis(ether anhydride) derived from 2,3-dihydroxynaphthalene gave strong solvent-cast films with high moduli extensions to break were modest except for the polymer from the diamine BAPB which extended to 150% prior to fracture.