Bio-inspired 4D printed regenerative thermosets enabled by synergistic dynamic reactions

Regeneration involves the process by which organisms (e.g. sponges) restore or replace lost or amputated body parts. Inspired by this concept, we report a strategy to realize the regeneration of 4D printed thermosetting photopolymers via synergistic coupling of reversible addition fragmentation chain transfer (RAFT) mediated polymer network and catalyst-free transesterification based dynamic crosslinks. The introduction of RAFT agent can precisely regulate the polymer network and generate the light responsive living polymer chains. The dynamic crosslinks allow the chemically cross-linked polymer network cleavage into polymer chains under external stimuli. Thus, the 4D printed regenerative thermosets based on digital light processing (DLP) technology can be reverted into living macromolecular chains, which can be regenerated by DLP 3D printing, giving them a second life like sponges. Moreover, the mechanical and functional properties of regenerative materials can be regulated on demand, promoting the circular lift cycle of 4D printed polymeric materials.