Highly Efficient Near-Infrared Photoinduced Electron/Energy Transfer-Reversible Addition-Fragmentation Chain Transfer Polymerization via the Energy Transfer Upconversion Mechanism

has been of particular interest owing to the deep penetration into opaque materials, giving rise to great potential for biomedical applications and solar photochemistry. Photoinduced electron/ energy transfer-reversible addition-fragmentation chain transfer poral control over the controlled radical polymerization process. Herein, we greatly extended the NIR region up to 980 nm by introducing rationally designed upconversion nanocrystals with low toxicity and resistance to photobleaching into PET-RAFT polymerization. Well-defined polymers with predictable molecular weight and narrow dispersity were prepared within a few hours by 980 nm NIR light-regulated PET-RAFT polymerization via the energy transfer upconversion mechanism. The livingness feature of this photopolymerization was confirmed by polymerization kinetics, chain extension experiments, and multiple controlled on-off light switching cycles. Furthermore, the polymerizations could be successfully performed using different monomers, in the presence of several visible light-proof barriers (i.e., pork/chicken skin) and even under aerobic conditions, demonstrating the multifold advantages of our approach.

Automated summary

In this study, the NIR region was extended up to 980 nm by introducing upconversion nanocrystals into PET-RAFT polymerization. Well-defined polymers with predictable molecular weight and narrow dispersity were prepared within a few hours by NIR light-regulated PET-RAFT polymerization. This photopolymerization showed livingness feature and could be performed under different conditions, demonstrating its multiple advantages.