Investigation of the thermal curing chemistry of the phenylethynyl group using a model aryl ether imide

The high temperature curing reactions of oligomers bearing two phenylethynyl groups have previously been utilized to produce attractive new materials, but are not well understood. A model aryl ether imide compound with one such moiety was used to elucidate some of the chemistry occurring during these processes. It was demonstrated that oligomeric molecular weight soluble products were formed by thermal initiation at 375 degrees C under nitrogen during these reactions, along with low molecular weight fragments derived from the model compound. These fragments were demonstrated to contain aliphatic protons in place of the phenylethynyl group and constitute about 5% of the overall material. Reactions of the model compound with deuterated biphenyl indicated that the reactive intermediates formed from the phenylethynyl moiety are able to abstract aromatic deuterium atoms in the presence of aromatic protons. However, these fragments appear to be side products not directly involved with the main curing reactions that occur after most of the carbon-carbon triple bonds have been reacted. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.