"Polymer to polymer" recycling and body-temperature triggered shape memory of a carvone-based epoxy thermoset system achieved using a thiol-Michael covalent adaptable network

Environmental economics is intensifying the necessity for the advancement of recycling technologies to address the increasing volume of discarded thermoset polymers. Covalent adaptable networks (CANs) provide a new strategy for the recycling and functionalization of thermosetting resins. Herein, a carvone-based CAN is developed, in which thermally driven depolymerization of mechanically robust polymer networks is achieved by dynamic thiol-Michael bonds. The original cross-linking network can be retained through simple drying and hot-pressing steps without purifying degradation products. The reversibility of the thiol-Michael group is demonstrated and the CAN exhibits shape memory behaviors triggered by human body temperature. We propose a micro-robotic injection model with good mechanical strength and fast response speed for complex 1D to 3D shape morphing in aqueous media at 37 degrees C. Our findings present a high-quality strategy to realize recycling and functionalization of bio-based thermoset resins and expand the toolbox for the preparation of bio-based CANs with thermo-responsive behavior. Closed-loop chemical recycling and body temperature-triggered shape memory of an epoxy thermoset system were achieved by using reversible thiol-Michael chemistry.