iridium iii

radical polymerization

light irradiation

imaging-guided photothermal

photopolymerization

free radical

conjugated microporous

conjugated polymer

Nature Communications

Efficient photopolymerization activated by nonharmful near-infrared (NIR) light is important for various biological applications. Here we propose a NIR light free-radical photoinitiator (PI) fabricated by incorporating oxime-ester coumarin functionality on the surface of upconversion nanoparticles (UCNPs). The coumarin groups of PI absorb the light emitted from the UCNP core, whereas the oxime ester groups undergo cleavage to form radicals. Upon irradiation at 980 nm, the mobile radicals, formed in a manner similar to that of dandelion seed release, initiate both free-radical and thiol-ene photopolymerizations. The superior efficiency of dandelion-like PIs assisted photopolymerizations can be attributed to the reduction of energy loss and increased local PI concentration due to Forster resonance energy transfer process and confinement effect, respectively. Moreover, the proposed PI system can initiate polymerization under low-power NIR laser and reduces the thermal side effects. The possibility of its potential use in deep curing applications was also demonstrated. Photo-induced polymerizations are being utilized to design and fabricate macromolecular structures with spatial and temporal control. Here the authors use a near-infrared light free-radical photoinitiator consisting of oxime-ester coumarin functionalities on the surface of upconversion nanoparticles for free-radical and thiol-ene photopolymerizations.

Highly efficient dandelion-like near-infrared light photoinitiator for free radical and thiol-ene photopolymerizations