PET-RAFT facilitated 3D printable resins with multifunctional RAFT agents

The application of reversible addition-fragmentation chain-transfer (RAFT) agents in stereolithographic 3D printing has been seldom reported due to their tendency to reduce polymerization rates. In this work, multi-arm RAFT agents (1, 2, 3, 4 arms) were used in model photoresins that were 3D printed using a PET-RAFT polymerization system. These resins were efficiently 3D printed under ultra-low intensity green-light (?max = 530 nm, 0.32 mW cm-2) with a commercial DLP 3D printer. Optimization of printing conditions indicated that the storage moduli and glass transition temperature of 3D printed parts were increased, then plateaued with increasing curing time. Notably, a relatively low ratio of monofunctional RAFT agent was found to concurrently enhance storage modulus and fracture toughness in comparison with unmodified systems. In addition, changing the concentration and functionality of RAFT agents provided control over material mechanical properties in a broad span. With comprehensive knowledge of these properties, these photoresins should allow the expansion of advanced materials for 3D printing.