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Article Dans Une Revue Chem Année : 2020

Visible-Light-Initiated Free-Radical Polymerization by Homomolecular Triplet-Triplet Annihilation

Résumé

Polymerization reactions initiated by ultraviolet light are ubiquitous in scores of industrial applications but would markedly benefit from visible-light activation to overcome stability, energy consumption, light penetration, and sample geometry limitations The current work lever-ages visible-light-driven homomolecular triplet-triplet annihilation (TTA) in zinc(II) meso-tetraphenylporphyrin (ZnTPP) to initiate facile free-radical polymerization in trimethylolpropane triacrylate (TMPTA) and methyl acrylate (MA) monomers through ultrafast electron transfer quenching. Selective Q-band (S-1) excitation of ZnTPP in the green or yellow sensitizes TTA occurring between two (ZnTPP)-Zn-3* energized chromophores, ultimately generating the highly reducing S-2 excited state on one ZnTPP molecule (E-red = 2.13 V versus saturated calomel electrode, SCE). Subsequently, this S-2 state engages in electron transfer with TMPTA or MA, thereby initiating the radical polymerization process. Bimolecular electron transfer was confirmed through optically gated fluorescence upconversion. FT-IR and EPR spin-trapping experiments verified visible-light-initiated polymerization leading to the formation of well-defined macro- and microscopic objects.

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Chimie
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Dates et versions

hal-03035995 , version 1 (20-04-2021)

Identifiants

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Nancy Awwad, Anh Thy Bui, Evgeny O. Danilov, Felix N. Castellano. Visible-Light-Initiated Free-Radical Polymerization by Homomolecular Triplet-Triplet Annihilation. Chem, 2020, 6 (11), pp.3071-3085. ⟨10.1016/j.chempr.2020.08.019⟩. ⟨hal-03035995⟩
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