Rapid, visible light-controlled cationic polymerization of vinyl ethers for 3D printing of chemically reprocessable networks under ambient conditions

Abstract

Light-mediated 3D printing techniques have gained significant interest due to the inherent advantages of light as external stimuli, including spatiotemporal control and easy access. As 3D printing processes require rapid polymerization, free radical or cationic polymerization methods are used. However, these polymerization reactions are limited to the production of materials with properties that cannot be chemically altered post-printing. In this work, a rapid, open-to-air photo-controlled cationic reversible addition-fragmentation chain-transfer polymerization of vinyl ethers is demonstrated in the presence of a three-component photoinitiating system comprising a photosensitizer, electron donor, and acceptor as co-initiators under the irradiation with blue light. The polymerization mechanism shows rapid kinetics and controlled, living polymerization characteristics. Trithiocarbonate chain ends of poly(isobutyl vinyl ethers) are reactivated to produce block copolymers with cyclohexyl vinyl ethers. The rapid kinetics and water tolerance of the reported system enable the 3D printing of polymeric solids under ambient (e.g., room temperature and open to air) conditions, followed by the effective reactivation of trithiocarbonate chain ends to post-synthetically modify the object with an acrylate-based fluorescent monomer via a controlled radical polymerization strategy.