Recent advances on squaraine-based photoinitiators of polymerization

Abstract

The development of photoinitiating systems activable in the visible and the nearinfrared region is an active research field. Compared to the traditional UV photopolymerization for which the light penetration into the photocurable resin remains limited, a significant enhancement of this latter can be obtained in the visible and the near infrared range so that the scope of applications of photopolymerization can be revolutionized. Among dyes whose absorption can be facilely tuned, squaraines can be cited as relevant examples. Depending on the peripheral groups introduced on both sides of the central fourmembered squaric ring, absorptions ranging from 400 to 1000 nm can be obtained. In this review, an overview of the recent development concerning the squaraines-based photoinitiating systems is provided. To evidence the interest of these new photoinitiating systems, comparisons with reference systems will be established.

Recent advances on coumarin-based photoinitiators of polymerization

“…Over the years, a wide range of structures have thus been examined for this purpose and naphthalimides, [23][24][25][26][27][28][29][30][31][32][33][34][35] squaraines, [36][37][38][39] iron complexes, [40][41][42][43][44][45][46] thioxanthones, [47][48][49][50][51][52][53][54][55][56] 2,3-diphenylquinoxaline derivatives, [57,58] iridium complexes, [59][60][61][62][63][64][65] perylenes, [66][67][68] chalcones, [69][70][71][72]…”

Recent progress in the development of highly active dyeing photoinitiators based on 1,3-bis(p-substituted phenylamino)squaraines for radical polymerization of acrylates

“…This is primarily related to beneficial spectral properties and good biological activity. 86 The squarylium dyes play a key role in photodynamic therapy (PDT). 87 Unfortunately, for many years an upward trend in the incidence of various types of cancer has been observed around the world.…”

Recent Advances in bis-Chalcone-Based Photoinitiators of Polymerization: From Mechanistic Investigations to Applications

“…This specificity is notably used advantageously with photopolymerizable glues and dental adhesives. Considering that visible light photopolymerization can be activated between 400 and 800 nm, numerous dyes absorbing in the visible range have been proposed, as exemplified with acridine-1,8-diones [36][37][38], carbazoles [39][40][41][42][43][44], pyrenes [45][46][47][48][49][50], iridium complexes, [51][52][53][54][55][56][57][58][59], copper complexes [60][61][62][63][64][65][66][67][68][69][70], squaraines [71][72][73], camphorquinones [74,75], perylenes [76][77][78], iodonium salts [79][80][81], benzophenones [82]...…”