The influence of multiple ortho-substituted phenylenes on the nature of poly(ether imide)s

The new ortho-aminophenyl diamine 1,2-bis(2′-aminophenoxy)benzene has been synthesized and polymerized with 1,2-bis(3′,4′dicarboxyphenoxy)benzene dianhydride to yield a poly(ether imide) with four ortho-catenated phenylenes per structural repeat unit. The polymer has been characterized by gel permeation chromatography and MALDI-TOF mass spectrometry and shown to contain a large proportion of oligomers. The oligomers have been found to be primarily macrocyclic oligomers with two to 10 repeat units. The results are contrasted with the high-molecular-weight polyimides formed from corresponding para-aminophenoxy diamines. It is concluded that either the ortho-aminophenoxy moiety or the large sequence of ortho-catenated phenylene rings gives a high propensity for ring closure and macrocycle formation in competition with propagation.