Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

Abstract

Metal complexes are used in numerous chemical and photochemical processes in organic chemistry. Metal complexes have not been excluded from the interest of polymerists to convert liquid resins into solid materials. If iridium complexes have demonstrated their remarkable photochemical reactivity in polymerization, their high costs and their attested toxicities have rapidly discarded these complexes for further developments. Conversely, copper complexes are a blooming field of research in (photo) polymerization due to their low cost, easy syntheses, long-living excited state lifetimes, and their remarkable chemical and photochemical stabilities. Copper complexes can also be synthesized in solution and by mechanochemistry, paving the way towards the synthesis of photoinitiators by Green synthetic approaches. In this review, an overview of the different copper complexes reported to date is presented. Copper complexes are versatile candidates for polymerization, as these complexes are now widely used not only in photopolymerization, but also in redox and photoassisted redox polymerization processes.

Efficacy Modeling of New Multi-Functional Benzophenone-Based System for Free-Radical/Cationic Hybrid Photopolymerization Using 405 nm LED

“…Above equations indicate that conversions for FRP and CP are given by the interaction of (T,R,S) and M, and R' and M, respectively. We note that the co-additive, For comprehensive modeling we will use the so-called quasi-steady state assumption [15,18]. The life time of the singlet and triplet states of photosensitizer, the triplet state (T), and the radicals (R, S' and S), since they either decay or react with cellular matrix immediately after they are created.…”

“…Organic dyes used as visible light photosensitizers of polymerization have been extensively studied [12,13], in which high extinction coefficients and their long-living excited states, enabling the photosensitizers to react efficiently with various additives in the photocurable resins. For cost effective with long-living excited states, copper complexes have been used as a new polymerization approach enabling the formation of acetylacetonate radicals by redox reaction with a phosphine and to initiate the free radical polymerization (FRP) of acrylates or the free radical promoted cationic polymerization (CP) of epoxides [14][15][16][17]. Recently, Coumarin as dual function of photoinitiators in photo-oxidation or photo-reduction in visible light were reported [18][19][20].…”

Lawsone Derivatives as Efficient Photopolymerizable Initiators for Free-Radical, Cationic Photopolymerizations, and Thiol—Ene Reactions

“…In particular, relevant reviews [ 3 , 4 , 6 ] have described the recent progress photoinitiating strategies envisaged to perform polymerization under light irradiation. Notably, new photocatalytic systems based on three-component photoinitiating systems [ 7 , 8 ] have been put to the forefront without considering environmental issues.…”

Efficacy Analysis of In Situ Synthesis of Nanogold via Copper/Iodonium/Amine/Gold System Under a Visible Light

“…Organic dyes used as visible light photosensitizers of polymerization have been extensively studied [12,13], in which high extinction coefficients and their long-living excited states, enabling the photosensitizers to react efficiently with various additives in the photocurable resins. For cost effective with long-living excited states, copper complexes have been used as a new polymerization approach enabling the formation of acetylacetonate radicals by redox reaction with a phosphine and to initiate the free radical polymerization (FRP) of acrylates or the free radical promoted cationic polymerization (CP) of epoxides [14][15][16][17]. Recently, Coumarin as dual function of photoinitiators in photo-oxidation or photo-reduction in visible light were reported [18][19][20].…”