LAUSR

Abstract Epoxy resins based on commonly used epoxy compounds, various anhydrides and CO2-protected N-heterocyclic carbenes (NHCs), which combine the favorable properties of fast curing at low reaction temperatures, pot life in the range of hours to days and full homogeneity in the form of low-viscosity liquids, are presented. These characteristics are achieved by careful tuning of the components. 1,3-Dimethylimidazolium-2-carboxylate (5u-Me-CO2) as a thermally latent organocatalyst offers facile one-step preparation and robustness towards atmospheric conditions as well as the high reactivity required once the polymerization is “switched on” by heating. A systematic screening of several epoxy compounds and 14 different anhydrides is conducted to identify the monomers that are suited best for rapid monomer consumption and thus for low curing temperatures. From these experiments, more than 15 different systems were found where a homogeneous liquid can be formed in the absence of further additives (no solvent or reactive thinner). Several of these one-component mixtures were investigated more detailed by in-situ DSC and rheology measurements. In general, the combination of aliphatic epoxides and low-melting or liquid anhydrides delivers the fastest polymerization under the mildest conditions, while maintaining a very low initial viscosity (