Photoinitiation Mechanism and Ability of Monoamino‐Substituted Anthraquinone Derivatives as Cationic Photoinitiators of Polymerization under LEDs

Abstract

The design and development of photoinitiating systems applicable to UV or even visible light delivered from light‐emitting diodes (LEDs) has been attracting increasing attention due to their great potential applications in various fields. Compared to the strategy of synthesizing novel compounds, the exploration of existing chemicals with interesting photochemical/photophysical properties for their usage as photoinitiators is more appealing and easily commercialized. Nevertheless, a number of compounds such as monoamino‐substituted anthraquinone derivatives, which are intensively investigated for their photophysical and photochemical properties, have seldom been studied for their roles as photoinitiators under LED irradiation. Herein, three monoamino‐substituted anthraquinone derivatives, that is, 1‐aminoanthraquinone, 1‐(methylamino)anthraquinone and 1‐(benzamido)anthraquinone, are studied for their potential as photoinitiators. The photoinitiation mechanism of these monoamino‐substituted anthraquinone derivatives, when combined with iodonium salt, is first clarified using computational quantum chemistry, fluorescence, steady‐state photolysis, and electron spin resonance spin‐trapping techniques. Then, their photoinitiation ability for the cationic photopolymerization of epoxide and divinyl ether monomers is also investigated.

Novel D–π-A and A–π-D–π-A three-component photoinitiating systems based on carbazole/triphenylamino based chalcones and application in 3D and 4D printing

“…An efficient photoinitiator (PI) plays an essential role in the photopolymerization process, which induces the rapid conversion of liquid monomers into highly crosslinked solid polymers by absorbing the appropriate wavelengths of light and generate reactive species (e.g. cations, free radicals, anions…) [11][12][13]. Nevertheless, the majority of the commercially available photoinitiators remains UV light sensitive.…”

Substituent Effects on Photoinitiation Ability of Monoaminoanthraquinone‐Based Photoinitiating Systems for Free Radical Photopolymerization under LEDs

“…These compounds were recently investigated as photoinitiators for the cationic polymerization of epoxide and divinyl ether monomers under UV, blue, or green LEDs. [ 12 ] In the present work, their suitability for free radical photopolymerization of various (meth)acrylate monomers is investigated.…”

“…These processes exhibit similar thermodynamic favourabilities to those that have been studied previously and have been shown both theoretically and experimentally to undergo fast electron transfer. [ 12 ]…”

“…The fluorescence emissions of AAQ, MAAQ, and BAAQ (associated with their excited singlet states) have been reported previously. [ 12 ] As shown in Figure , the fluorescence of BAAQ was quenched with the addition of TEAOH…”

Penta‐Hydroxy Flavones‐Based Photoinitiating Systems for Free Radical, Cationic, and Thiol‐Ene Polymerization upon Exposure to Mild Blue LEDs

“…[37] The phenomenon was also observed for other flavone and anthraquinone derivatives substituted with diverse groups at varied positions which resulted in various light absorption properties. [9,14,29,31,34,38] Scheme 1. Chemical structures of the investigated photoinitiators (morin and quercetin), additives (NPG, EDB, and Iod), and monomers (Bis-GMA, TEGDMA, TMPTA, DVE-3, Trione, and TriThiol).…”