An amino-capped aniline trimer (ACAT) in emeraldine base form was reacted with an epoxy resin to produce intercrosslinked networks. The quinoid structure of the ACAT was able to crosslink on curing and, thus, led to a very high glass-transition temperature of the cured resin. The epoxy resin cured with the ACAT showed superior thermal properties over the resins cured with p-phenylenediamine and 4,4'-diamino diphenylamine. These findings were based on differential scanning calorimetry, IR, dynamic mechanical analysis, and thermogravimetric analysis data. (c) 2006 Wiley Periodicals, Inc.