Issue 12, 2022

Bio-based porphyrins pyropheophorbide a and its Zn-complex as visible-light photosensitizers for free-radical photopolymerization

Abstract

A chlorophyll a derivative, namely pyropheophorbide a (Pyro), and the corresponding zinc(II) complex (Zn-Pyro) were used for the first time as visible-light photosensitizers (PS) for free-radical photopolymerization (FRP) when combined with an iodonium salt derivative (Iod) and different amines. The reaction mechanisms involving Pyro and Zn-Pyro coupled with Iod and/or MDEA were deeply investigated using steady-state photolysis, fluorescence experiments, laser-flash photolysis (LFP), and electron-paramagnetic resonance spin trapping (EPR-ST) methods. According to the remarkable absorption properties of Pyro and Zn-Pyro, FRP could occur under blue-light (LED@405 nm and LED@455 nm), and under red-light (LED@625 nm and LED@660 nm) irradiation. Conversions of up to 80% of PEG-diacrylate were obtained using two-component (PS/Iod and PS/amine) or three-component (PS/Iod/amine) photoinitiating systems. Several amines used as co-initiators were compared, and N-methyl-diethanolamine (MDEA) and the bio-based thiol-amine cysteamine (Cys) exhibited very interesting kinetic results. Notably, the performances in FRP obtained with the Zn-Pyro/Iod/Cys system constitute a promising step in the development of a fully bio-based photoinitiating system.

Graphical abstract: Bio-based porphyrins pyropheophorbide a and its Zn-complex as visible-light photosensitizers for free-radical photopolymerization

Supplementary files

Article information

Article type
Paper
Submitted
28 Dec. 2021
Accepted
06 Febr. 2022
First published
07 Febr. 2022

Polym. Chem., 2022,13, 1658-1671

Bio-based porphyrins pyropheophorbide a and its Zn-complex as visible-light photosensitizers for free-radical photopolymerization

L. Breloy, V. Brezová, S. Richeter, S. Clément, J. Malval, S. Abbad Andaloussi and D. Versace, Polym. Chem., 2022, 13, 1658 DOI: 10.1039/D1PY01714D

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