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

17 January 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


A visible light absorbing, anthraquinone derivative 1-tosyloxy-2-methoxy-9,10-anthraquinone (QT) mediates both cationic and radical polymerizations depending on the intensity of visible light used. A previous study showed that this initiator generates para-toluenesulfonic acid through a stepwise, two-photon excitation mechanism. Thus, under high intensity irradiation, QT generates acid in sufficient quantities to catalyze the cationic ring opening polymerization of lactones. However, under low intensity (lamp) conditions, the two-photon process is negligible, and QT photooxidizes DMSO, generating methyl radicals which initiate the RAFT polymerization of acrylates. This dual capability was utilized to switch between radical and cationic polymerizations to synthesize a copolymer using a one-pot procedure.


triplet state
ring-opening polymerization
RAFT polymerization

Supplementary materials

Supporting Information for: Lamp vs. Laser: A Photoinitiator that Promotes Radical Polymerization at Low Visible Light Intensities and Cationic Polymerization at High Intensities
Synthetic Procedures Photopolymerization Procedures UV/Vis Spectra GPC Traces NMR Spectra


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