Closed-Loop Recycling and Body-Temperature Triggered Shape Memory of Epoxy Thermoset System Achieved by Thiol-Michael Covalent Adaptable Network

Environmental economics is accelerating the urgency to develop recycling technologies for the ever-growing quantity of discarded thermoset polymers. The covalent adaptable networks (CANs) provide a new strategy for the recycling and functionalization of thermosetting resins. Herein, a carvone-based CANs is developed, in which the orthogonal reactivity of an irreversible thioether and a dynamic thiol-Michael bond enables both thermal curing and thermally driven depolymerization of mechanically robust polymer networks. The dynamic behaviors of the thiol-Michael group are demonstrated and the CANs exhibit 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 °C. Our findings present a high-quality strategy to realize recycling and functionalization of thermoset resin and expand the toolbox for the preparation of smart CANs with thermo-responsive behavior.