Rapid Cross-Linking of Epoxy Thermosets Induced by Solvate Ionic Liquids

The high-volume manufacture of fiber-reinforced composites faces a huge challenge because long resin curing times put a low ceiling on the total output of parts produced per year. To translate the benefits from using epoxy in large-volume production platforms, cure cycle times of less than 1 min must be achieved. In this work, we report solvate ionic liquids (SILs) as simple and efficient rapid curing catalytic additives in epoxy systems. Ultrafast curing was observed at low levels of 1-5% of SIL in epoxy resin, and the cure rate is enhanced up to 26-fold without compromising the mechanical and thermal properties. Further investigations revealed that enhancement in the cure rate is dependent on the type of SILs employed, influenced by the metal center, the ligands around the metal, and the identity of the counter anion. The relative Lewis acidity of each of the active complexes was calculated, and the rapid cure effect was attributed to the activation of the epoxide moietyviathe Lewis acidic nature of the SIL. Making epoxy thermosets rapidly processable enables enormous benefits, finding applications in a whole variety of transformation methods that exist for traditional glass and metals.