Sunlight Induced Polymerization Photoinitiated by Novel Push–Pull Dyes: Indane‐1,3‐Dione, 1H‐Cyclopenta[b]Naphthalene‐1,3(2H)‐Dione and 4‐Dimethoxyphenyl‐1‐Allylidene Derivatives

Abstract

The free radical polymerization of acrylates photo-initiated by push-pull dye-based photoinitiating systems (PISs) is widely investigated in previous works. As a supplementary investigation on push-pull dyes, here in this article, 25 push-pull structures comprising electron acceptors derived from indane-1,3-dione and 1H-cyclopenta[b]naphthalene-1,3(2H)-dione (series 1) and 4-dimethoxyphenyl-1-allylidene moieties (series 2) and various electron donors are synthesized and examined as innovative structures for photoinitiation. Among the two series of dyes examined in this work and by monitoring the polymerization processes by RT-FTIR measurements, four dyes are determined as exhibiting excellent photoinitiation performances and these dyes are selected to perform further studies concerning the chemical mechanisms occurring inside the three-component PISs, for example, steady state photolysis, fluorescence quenching measurements, and cyclic voltammetry. Markedly, their reactivity is also proved by photoinitiation performance upon sunlight. These results prompt us to develop high performance push-pull dyes as photosensitizers and sunlight can be used as a mild and ecofriendly light source, which can advantageously replace LEDs for the free radical photopolymerization in the future. Finally, the formation of 3D patterns with an excellent gradient of resolution is successfully achieved by the direct laser write (DLW) with/without silica fillers.

Push-pull dyes based on Michler's aldehyde: Design and characterization of the optical and electrochemical properties

“…[3][4][5] Benefiting from their intense absorption bands in the visible range, push-pull dyes thus constitute candidates of choice for applications such as dyes for non-linear optics, [6][7][8] active layers for solar cells, [9][10][11][12][13][14][15] biological labelling [16,17] organic field effect transistors [18][19][20][21][22][23][24] photochroms [25][26][27][28][29] or as visible light photoinitiators of polymerization. [30][31][32][33][34][35][36][37][38][39] With aim at optimizing the synthetic routes of numerous organic compounds, recently, photoredox catalysis making used of pushpull dyes as photosensitizers has emerged as a promising approach which was applied to various chemical transformations. [40][41][42][43] Considering that the intramolecular charge transfer (ICT) band constitutes the key element of push-pull dyes focusing the interest of numerous researchers, intensity and position of this absorption band can be easily modified by applying the following principles.…”

Chemical engineering around the 5,12-dihydroindolo[3,2-a]carbazole scaffold: Fine tuning of the optical properties of visible light photoinitiators of polymerization

“…[82] In the context of visible light photopolymerization which requires dyes to absorb in the visible range, Claisen-Schmidt and Knoevenagel reactions are reactions of choice for the design of push-pull dyes. [42,[83][84][85][86][87] Additionally, these reactions can be carried out in green conditions, an alcohol being used as the solvent and a few drops of amine are sufficient to catalyze the two reactions. To end, push-pull dyes can be easily recovered in pure form by precipitation in alcohols, facilitating the purification process.…”

Recent advances on visible light Triphenylamine-based photoinitiators of polymerization

“…Indeed, if the light penetration is of a few millimeters at 405 nm, this latter can reach 5 cm at 800 nm, enabling the polymerization of thick and filled polymers. With aim at developing highly efficient photoinitiating systems, a wide range of structures have been examined over the years and porphyrins, [21,22] pushpull dyes, [23][24][25][26][27][28][29][30][31][32][33][34][35][36] iodonium salts, [37][38][39][40][41][42][43] carbazoles, [44][45][46][47][48][49][50][51] phenothiazines, [52,53] cyanines, [54][55][56][57][58] zinc complexes, [59] diketopyrrolopyrroles, [60][61][62] iridium complexes, [63][64][65][66][67]…”