Photoinduced Free Radical Promoted Cationic RAFT Polymerization toward Living 3D Printing

Three-dimensional (3D) printing utilizing controlled polymerization systems is emerging as a powerful approach to fabricate living objects, which can be further modified with various functionalities. Here, we report photoinduced free radical-promoted cationic reversible addition-fragmentation chain transfer (RAFT) polymerization under broad wavelengths from ultraviolet (UV) to near-infrared (NIR) light. A commercially available iron catalyst, cyclopentadienyl iron dicarbonyl dimer (Fe-2(Cp)(2)(CO)(4)), was used as the photocatalyst, and several diphenyliodonium salts were examined as oxidants. Various poly(vinyl ether)s with controlled molecular weights and a narrow dispersity (1.06-1.32) were prepared through this method. Relatively high chain-end fidelity can be observed and has been demonstrated by successful chain-extension experiments. In addition, benefiting from the penetrating ability of NIR light, 3D objects with different thicknesses were achieved by employing stereolithography-based 3D printing techniques. Furthermore, the postfunctionalization of these 3D printed objects with fluorescent monomers provides a facile method to build 3D objects with complex functionality and potential applications in anticounterfeiting materials.

Automated summary

A photoinduced polymerization technique is reported in this study, which can achieve controlled molecular weights and narrow dispersity of polymers at different wavelengths, and can also be used for producing 3D printed objects of varying thicknesses utilizing stereolithography.