Synthesis and property comparison of isomeric AB-type homo- and copoly(etherimide)s

AB-type homo- and copoly(etherimide)s were prepared by the polymerization of 3- and 4-(3,4-dicarboxyphenyloxy)aniline hydrochlorides (3A and 4A) at 160 °C in dimethylacetamide in the presence of triethylamine and triphenyl phosphite. After the structures of the polymers were characterized, their solubilities, ultraviolet–visible (UV–vis) absorption behaviors, thermal properties, and crystallinities were measured, and these properties are discussed with respect to the structure of the homopolymers and the composition of the copolymers. Poly(etherimide) (PEI) derived from 3A [PEI(3A)] was amorphous and soluble in chloroform on heating, whereas that derived from 4A [PEI(4A)] was crystalline and insoluble in common organic solvents even on heating. In UV–vis absorption spectra, PEI(4A) showed a small bathochromic shift relative to N-phenylphthalimide, but PEI(3A) did not. PEI(3A) revealed a glass-transition temperature (Tg) at 195 °C, but no Tg was detectable for PEI(4A). All the measured physical properties of the copoly(etherimide)s showed a good dependence on their composition between PEI(3A) and PEI(4A).