Design of photoinitiating systems based on the chalcone-anthracene scaffold for LED cationic photopolymerization and application in 3D printing

Abstract

In this study, light-emitting diodes (LEDs) used as secure, low-cost and possessing long emission wavelengths irradiation sources were applied in photopolymerization. Seven novel anthracene derivatives (noted A1-A7) have been proposed and evaluated in photosensitive systems for LED photopolymerization. Three final function conversions of epoxy using some anthracene/iodonium salt systems were even higher than the well-established dibutoxyanthracene (DBA)/iodonium salt benchmark system. In addition, due to the good light absorption properties, the cationic photopolymerization also was carried out in the presence of the chalconeanthracene/iodonium salt systems under LED@470 nm or laser diode@447 nm irradiation (not possible to do with the reference DBA systems). Remarkably, these derivatives were also able to sensitize sulfonium salts. The photochemical reactivity of anthracenes was investigated through steady state photolysis and fluorescence quenching experiments. Furthermore, the proposed interaction mechanisms of chalcone-anthracene derivatives and additives (iodonium salt and amine) were discussed using the free energy changes of electron transfer reactions. Interestingly, the cationic photopolymerization of A5/iodonium salt system was applied in 3D printing and the 3D patterns showed a good spatial resolution.

Recent advances on chalcone-based photoinitiators of polymerization

“…Recently, a series of anthracene-based chalcones was proposed as visible light photoinitiators valuable in 3D printing applications (See Figure 17). [80] By use of a polyaromatic donor in these structures, a significant enhancement of the light absorption properties at 405 nm could be obtained for the different chalcones compared to 9,10dibutoxyanthracene in which the push-pull effect does not exist (See Table 4 and Figure 18). Among the most interesting finding of this work, cis/trans photoisomerization of chalcones was determined as strongly affecting the photoinitiating ability.…”

“…3D patterns obtained upon polymerization of EPOX at 405 nm using the twocomponent C51/Iod (0.5%/1%, w/w) system. Reprinted from[80] Copyright (2020), with permission from Elsevier In 2021, several of the aforementioned structures were revisited in a same study, by slightly modifying the substitution pattern [237]. Thus, the methoxy group of C49 and C46 was replaced by an ethoxy group in C56 and C57, unaffecting the optical properties compared to those determined in the previous work.…”

“…UV-visible absorption spectra of chalcones C47-C53 and the reference dye DBA in acetonitrile. Reprinted from[80] Copyright (2020), with permission from Elsevier Interestingly, almost absorption of DBA being too low at this wavelength to efficiently initiate a polymerization process. Markedly, the best EPOX conversions were obtained with chalcone C50 and C51, the monomer conversions peaking at 33 and 36% respectively.…”

Photopolymerization of Zeolite Filler‐Based Composites for Potential 3D Printing Application and Gas Adsorption Applications

“…[13][14][15][16] Therefore, photopolymerization is one of the most common polymerization methods applied in 3D printing industry. [17][18][19][20] Pure polymer products obtained by 3D printers are only often used for conceptual prototypes, due to their inherent lack of appropriated mechanical properties and functionality. [13,21] To improve the mechanical properties and enhance functionalities of 3D printed objects, different types of filler are selected to polymers to form different kinds of composite materials, such as fibers [22,23] , particles [24][25][26] and nanomaterials [27,28] .There are also many researchers developing UV-curable particle-free ceramic compositions for stereolithography-based 3D printing technologies, which is a potential alternative to the common particle-based compositions.…”

High-Performance UV-Vis Light Induces Radical Photopolymerization Using Novel 2-Aminobenzothiazole-Based Photosensitizers

“…The increasing popularity of photopolymerization is related to numerous unique techniques, the interest towards photochemically initiated polymerization is constantly gaining importance [5]. The increasing popularity of photopolymerization is related to numerous unique advantages, such as low economic costs [6,7], high efficiency [8,9], the possibility of spatial and temporal control over the process [10,11] and a fast-curing rate [12]. These techniques are referred to as eco-friendly because of the possibility of using solvent-free polymerizable compositions with zero or a very low index of volatile organic compounds (VOCs), which are one of the major sources of environmental pollution.…”