Recyclable RAFT-3D Printing

Abstract

Recyclable 3D printing systems are urgently needed to address sustainability challenges in polymer manufacturing. Herein, we report a closed-loop 3D printing strategy based on reversible addition-fragmentation chain transfer (RAFT) step-growth polymerization, in which dynamic trithiocarbonate linkages are embedded into the polymer network. The resulting network is recyclable via RAFT interchange under 405nm irradiation in the presence of excess RAFT agents, regenerating oligomers bearing reactive chain-end groups. These intermediates can be directly re-crosslinked by adding stoichiometric vinyl monomers, thereby reconstructing the original polymer structure. Moreover, upcycled materials can be easily obtained by varying the vinyl monomer concentration. Digital light processing (DLP)-based 3D printing of these resins yields robust objects with tunable mechanical properties (Young's modulus from 0.78 to 835 MPa). Post-printing functionalization and erasure via RAFT interchange further demonstrate the dynamic and "living" features of this system. This catalyst-free, modular approach eliminates the need for specialized dynamic covalent monomers, offering a practical and sustainable platform for recyclable RAFT-based 3D printing.