Photoinduced 3D Printing via Hybrid RAFT/Cationic Polymerization

The integration of mechanical adaptability and functional versatility in 3D-printed materials remains a central challenge in additive manufacturing. Here, we introduce a photoinduced 3D printing strategy that couples reversible addition–fragmentation chain transfer (RAFT) polymerization with cationic ring-opening polymerization (CROP) in a single resin. Using a dual-functional monomer, 3,4-epoxycyclohexylmethyl acrylate (ECMA), and a bis(4-tert-butylphenyl)iodonium hexafluorophosphate/2-isopropylthioxanthone (Iod/ITX) photoinitiating system, orthogonal polymerizations are triggered under 405 nm light to generate dual-cross-linking networks. The resulting materials exhibit unprecedented mechanical tunability, with Young’s moduli spanning from 8.4 MPa to 2.26 GPa, by varying monomer ratios, RAFT agent content, and postcuring conditions. RAFT-mediated chain ends enable postprinting welding and surface functionalization, while spatial control of radical versus cationic curing yields objects with coexisting soft and rigid domains. This hybrid platform establishes a versatile design principle for mechanically adaptive and multifunctional 3D-printed materials with broad potential in soft robotics, biomimetics, and responsive devices.