Keto‐coumarin scaffold for photoinitiators for 3D printing and photocomposites

Abstract

The purposes of this paper are moving toward (a) the development of a new series of photoinitiators (PIs) which are based on the keto-coumarin (KC) core, (b) the introduction of light-emitting diodes (LEDs) as inexpensive and safe sources of irradiation, (c) the study of the photochemical mechanisms through which the new PIs react using different techniques such as Fourier transform infrared, UV-visible or fluorescence spectroscopy, and so on, (d) the use of such compounds (presenting good reactivity and excellent photopolymerization initiating abilities) for two specific and high added value applications: 3D printing (@405 nm) and preparation of thick glass fiber photocomposites with excellent depth of cure, and finally (e) the comparison of the performance of these KC derivatives versus other synthesized coumarin derivatives. In this study, six well-designed KC derivatives (KC-C, KC-D, KC-E, KC-F, KC-G, and KC-H) are examined as high-performance visible-light PIs for the cationic polymerization of epoxides as well as the free-radical polymerization of acrylates upon irradiation with LED@405 nm. Excellent polymerization rates are obtained using two different approaches: a photooxidation process in combination with an iodonium (Iod) salt and a photoreduction process when associated with an amine (N-phenylglycine or ethyl 4-(dimethylamino)benzoate). High final reactive conversions were obtained. A full picture of the involved photochemical mechanisms is provided. K E Y W O R D S keto-coumarin, light-emitting diode, photocomposite, photoinitiator, photopolymerization, 3D printing resin

In Silico Design of Nitrocoumarins as Near-UV Photoinitiators: Toward Interesting Opportunities in Composites and 3D Printing Technologies

“…Moreover, the ability of coumarin derivatives to act as photosensitizers or photoinitiators has been deeply studied and influence of the substitution pattern was notably investigated. Parallel to coumarins, other derivatives such as keto-coumarins were also studied [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Recently, new coumarins have also been examined by us for 3D printing applications, photocomposites synthesis but also for the preparation of hydrogels (widely used in biomedical applications), highlighting the use of watersoluble photoinitiators [28].…”

Allyloxy ketones as efficient photoinitiators with high migration stability in free radical polymerization and 3D printing

“…The step width between the photocuring resin and the non-curing resin was about 50 μm, which is in accordance with the spot size of the laser beam, thus exemplifying an excellent spatial resolution. 41,42 The laser write results of TA set a good example for the effective free radical polymerization of acrylates initiated with the ketones-based threecomponent photoinitiating systems. Figure 10.…”

Recent advances on push–pull organic dyes as visible light photoinitiators of polymerization

“…Concomitant to the development of visible light photoinitiating systems, cheap, compact and lightweight irradiation setups have been developed such as the Light-emitting Diodes (LEDs) or the Laser diodes making the traditional irradiation systems obsolete. Over the years and in order their absorption spectra to perfectly fit with the emission spectra of the different visible light sources, a wide range of structures have been examined as visible light photoinitiators such as acridones 1, [18,19] acridine-1,8-dione 2, [20,21] benzophenones 3, [22][23][24][25] camphorquinones 4, [26,27] carbazoles 5, [28][29][30][31][32][33] chalcones 6, [34,35] chromones 7, [36][37][38] coumarins 8, [39][40][41][42][43] copper complexes 9, [44][45][46][47][48][49][50][51][52][53][54] cyclohexanones 10, [55][56][57] dihydroanthraquinone 11, [58] 2,3-diphenylquinoxaline derivatives 12, [59] diketopyrrolopyrrole 13, [60]…”