Design of ketone derivatives as highly efficient photoinitiators for free radical and cationic photopolymerizations and application in 3D printing of composites

Abstract

Herein, thirteen ketone derivatives composed of different cyclohexanone cores and peripheral moieties are designed, among which 10 ketones have never been synthesized before. These ketones are proposed as high‐performance photoinitiators for both free radical polymerizations and cationic polymerizations under soft conditions (visible LED@405 nm irradiation at room temperature). In combination with an amine and an iodonium salt (Iod), these ketones could be used in three−component photoinitiating systems to initiate the free radical polymerization of acrylates with distinct final conversions, among which the ketone−1/amine/Iod combination proved to be the most efficient one. Besides, the ketone−1/Iod two−component system also showed a remarkable photoinitiation ability for the cationic polymerization of epoxides. The photochemical sensitivity of ketone−1 in the presence of an amine and an iodonium salt was systematically investigated by steady state photolysis and excited state fluorescence quenching characterizations, respectively. Interestingly, macroscopic 3D patterns with excellent spatial resolution could be generated using the ketone−1/amine/Iod photoinitiating system for the free radical polymerization of acrylates. This high performance is also found useful to overcome the light penetration issue for the access to filled samples (silica) and the preparation of composites.

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

“…Following this initial work, another series of 13 bis-chalcones based on 6 different central cyclohexanones was examined in similar conditions to those used for the previous series (see Figure 9) [113]. From a synthetic viewpoint, all of these chalcones were obtained via a Claisen-Schmidt condensation, in a one-step reaction using aq.…”

“…The extractability and migratability of photoinitiators is a major issue that can drastically affect future uses of polymers. In this context, in order to reduce the extractability of dyes, polymerizable groups can be introduced, as exemplified with C32-C36; for comparison, C14 [113], previously studied, was used as a non-crosslinkable chalcone (see Figure 16) [110]. The comparison between the crosslinkable chalcone C36 and its non-crosslinkable version C14 revealed the remarkable migration stability of C36 compared to C14.…”

Novel chalcone derivatives with large conjugation structures as photosensitizers for versatile photopolymerization

“…Photopolymerization is one of the most promising methods for synthesizing polymer materials because of its low energy consumption, nonsolvent compositions, and high efficiency 1–5 . Photopolymerization is widely applied in various fields, such as microelectronics, 6 UV‐cured coatings, 7 3D microfabrication, 8–10 nanotechnology, 11,12 and biomedical applications 13 .…”

“…Photopolymerization is one of the most promising methods for synthesizing polymer materials because of its low energy consumption, nonsolvent compositions, and high efficiency. [1][2][3][4][5] Photopolymerization is widely applied in various fields, such as microelectronics, 6 UV-cured coatings, 7 3D microfabrication, [8][9][10] nanotechnology, 11,12 and biomedical applications. 13 Efficient photoinitiators (PIs) or photoinitiation systems (PISs) play an essential role in photopolymerization as they induce the rapid conversion of monomers into polymers by absorbing the appropriate wavelengths of light and generating reactive species, such as free radicals, 14 cations, 15,16 or anions.…”