Lamp vs Laser: A Visible Light Photoinitiator That Promotes Radical Polymerization at Low Intensities and Cationic Polymerization at High Intensities

A visible light absorbing anthraquinonederivative 1-tosyloxy-2-methoxy-9,10-anthraquinone(QT) mediates both cationic and radical polymerizationsdepending on the intensity of visible light used. A previous studyshowed that this initiator generates para-toluenesulfonicacid through a stepwise, two-photon excitation mechanism. Thus, underhigh-intensity irradiation, QT generates acid in sufficientquantities to catalyze the cationic ring-opening polymerization oflactones. However, under low-intensity (lamp) conditions, the two-photonprocess is negligible, and QT photooxidizes DMSO, generatingmethyl radicals which initiate the RAFT polymerization of acrylates.This dual capability was utilized to switch between radical and cationicpolymerizations to synthesize a copolymer using a one-pot procedure.

Automated summary

A visible light absorbing anthraquinone derivative, 1-tosyloxy-2-methoxy-9,10-anthraquinone (QT), can mediate both cationic and radical polymerizations depending on the intensity of visible light used. Under high-intensity irradiation, QT generates acid to catalyze the cationic ring-opening polymerization of lactones, while under low-intensity conditions, QT photooxidizes DMSO to generate methyl radicals for the RAFT polymerization of acrylates. This dual capability allows for switching between radical and cationic polymerizations in a one-pot synthesis.