Energy-efficient conversion of amine-cured epoxy resins into functional chemicals based on swelling-induced nanopores

The rapid growth of discarded or landfilled thermosetting plastics has caused serious environmental issue and significant waste of energy. Selective degradation of thermosetting polymers into useful chemicals under mild conditions may provide a sustainable approach to address this challenge. In this study, we developed a green and efficient method to cleave the crosslinks of amine-cured epoxy resin (EP) to produce new functional chemicals. Complete degradation was achieved using 4 mol/L of HNO3 incubated at 60°C for 3 h and it has a higher efficiency than conventional methods. The C-N bonds of EP were selectively cleaved without breaking the skeletal bonds. The swelling-induced nanopores in the EP caused by the microwave processing exposed the crosslinks that resulted in milder degradation conditions. The porous products could be readily separated and recovered. This study demonstrates a feasible approach for the recycling of thermosetting polymers under mild conditions.