Altmann Hagen J, Frey Wolfgang, Buchmeiser Michael R
Institute of Polymer Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany.
Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany.
Macromol Rapid Commun. 2020 Oct;41(20):e2000338. doi: 10.1002/marc.202000338. Epub 2020 Sep 9.
1,3-Dicyclcohexyl-6,9-dimethyl-1,3,6,9-tetraazaspiro[4.4]non-7-ene-2,4-dione, a spirocyclic parabanic acid derivative of N,N-dimethylimidazole, is used as thermally latent, protected N-heterocyclic carbene (NHC) in polymerizing anhydride-cured epoxide resins, and azepan-2-one, respectively. The protected carbene is synthesized from 1,3-dimethylimidazolium-2-carboxylate in the presence of two equivalents of cyclohexyl isocyanate. In the synthesis of epoxide resin thermosets, this class of latent NHC allows the production of fast and fully cured materials with high crosslinking content. Fast and complete conversion is found in the anionic ring opening polymerization (AROP) of azepan-2-one (ε-caprolactam, CLA) with and without additional activators.
