scholarly journals Monocomponent Photoinitiators based on Benzophenone-Carbazole Structure for LED Photoinitiating Systems and Application on 3D Printing

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1394 ◽  
Author(s):  
Shaohui Liu ◽  
Hong Chen ◽  
Yijun Zhang ◽  
Ke Sun ◽  
Yangyang Xu ◽  
...  
Keyword(s):  
Free Radical ◽  
3D Printing ◽  
Rational Design ◽  
Photophysical Properties ◽  
Synergetic Effect ◽  
Type Ii ◽  
Visible Absorption ◽  
Free Radical Photopolymerization ◽  
Iodonium Salt ◽  
Resonance Spin

In this article, different substituents (benzoyl, acetyl, styryl) are introduced onto the carbazole scaffold to obtain 8 novel carbazole derivatives. Interestingly, a benzoyl substituent, connected to a carbazole group, could form a benzophenone moiety, which composes a monocomponent Type II benzophenone-carbazole photoinitiator (PI). The synergetic effect of the benzophenone moiety and the amine in the carbazole moiety is expected to produce high performance photoinitiating systems (PISs) for the free radical photopolymerization (FRP). For different substituents, clear effects on the light absorption properties are demonstrated using UV-Visible absorption spectroscopy. Benzophenone-carbazole PIs can initiate the FRP of acrylates alone (monocomponent Type II photoinitiator behavior). In addition, fast polymerization rates and high function conversions of acrylate are observed when an amine and/or an iodonium salt are added in systems. Benzophenone-carbazole PIs have good efficiencies in cationic photopolymerization (CP) upon LED @ 365 nm irradiation in the presence of iodonium salt. In contrast, other PIs without synergetic effect demonstrate unsatisfied photopolymerization profiles in the same conditions. The best PIS identified for the free radical photopolymerization were used in three-dimensional (3D) printing. Steady state photolysis and fluorescence quenching experiments were carried out to investigate the reactivity and the photochemistry and photophysical properties of PIs. The free radicals, generated from the studied PISs, are detected by the electron spin resonance - spin trapping technique. The proposed chemical mechanisms are provided and the structure/reactivity/efficiency relationships are also discussed. All the results showed that the benzophenone-carbazole PIs have a good application potential, and this work provides a rational design route for PI molecules. Remarkably, BPC2-BPC4, C6, C8 were never synthetized before; therefore, 5 of the 8 compounds are completely new.

scholarly journals 3-Carboxylic Acid and Formyl-Derived Coumarins as Photoinitiators in Photo-Oxidation or Photo-Reduction Processes for Photopolymerization upon Visible Light: Photocomposite Synthesis and 3D Printing Applications

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1753
Author(s):  
Mahmoud Rahal ◽  
Bernadette Graff ◽  
Joumana Toufaily ◽  
Tayssir Hamieh ◽  
Guillaume Noirbent ◽  
...  
Keyword(s):  
3D Printing ◽  
Visible Light ◽  
High Performance ◽  
High Rate ◽  
Visible Absorption ◽  
Free Radical Photopolymerization ◽  
Rate Of Polymerization ◽  
Direct Laser ◽  
Iodonium Salt ◽  
Very High

In this paper, nine organic compounds based on the coumarin scaffold and different substituents were synthesized and used as high-performance photoinitiators for free radical photopolymerization (FRP) of meth(acrylate) functions under visible light irradiation using LED at 405 nm. In fact, these compounds showed a very high initiation capacity and very good polymerization profiles (both high rate of polymerization (Rp) and final conversion (FC)) using two and three-component photoinitiating systems based on coum/iodonium salt (0.1%/1% w/w) and coum/iodonium salt/amine (0.1%/1%/1% w/w/w), respectively. To demonstrate the efficiency of the initiation of photopolymerization, several techniques were used to study the photophysical and photochemical properties of coumarins, such as: UV-visible absorption spectroscopy, steady-state photolysis, real-time FTIR, and cyclic voltammetry. On the other hand, these compounds were also tested in direct laser write experiments (3D printing). The synthesis of photocomposites based on glass fiber or carbon fiber using an LED conveyor at 385 nm (0.7 W/cm2) was also examined.

scholarly journals Free Radical Photopolymerization and 3D Printing Using Newly Developed Dyes: Indane-1,3-Dione and 1H-Cyclopentanaphthalene-1,3-Dione Derivatives as Photoinitiators in Three-Component Systems

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 463 ◽  
Author(s):  
Ke Sun ◽  
Corentin Pigot ◽  
Hong Chen ◽  
Malek Nechab ◽  
Didier Gigmes ◽  
...  
Keyword(s):  
Free Radical ◽  
3D Printing ◽  
High Performance ◽  
Chemical Mechanisms ◽  
Esr Spin Trapping ◽  
Free Radical Photopolymerization ◽  
Spin Resonance ◽  
Component Systems ◽  
Iodonium Salt ◽  
First Time

The design of photoinitiating systems with excellent photochemical reactivities at 405nm LED is one of the obstacles to efficiently promote free radical polymerization in mild conditions (e.g., low light intensity, under air). Here, our actual search for new multicomponent photoinitiating systems at 405nm LED prompts us to develop new dyes based on push–pull structures. In the present paper, we chose two series of new dyes which possess indane-1,3-dione and 1H-cyclopenta naphthalene-1,3-dione groups as the electron-withdrawing groups, since they have the great potential to behave as sensitive and remarkable photoinitiators in vat photopolymerization/3D printing. When incorporated with a tertiary amine (ethyl dimethylaminobenzoate EDB, used as electron/hydrogen donor) and an iodonium salt (used as electron acceptor) as the three-component photoinitiating systems (PISs), and among a series of 21 dyes, 10 of them could efficiently promote the free radical photopolymerization of acrylates. Interestingly, steady state photolysis experiments revealed different behaviors of the dyes. Fluorescence experiments and free energy change calculations for redox processes were also carried out to investigate the relevant chemical mechanisms. Additionally, the formation of radicals from the investigated PISs was clearly observed by electron spin resonance (ESR) spin-trapping experiments. Finally, stereoscopic 3D patterns were successfully fabricated by the laser writing technique. In this work, the use of push–pull dyes based on the naphthalene scaffold as photoinitiators of polymerization is reported for the first time in a systematic study aiming at investigating the structure–performance relationship for irradiation carried out at 405 nm. By carefully selecting the electron donors used in the two series of push–pull dyes, novel and high-performance photoinitiating systems operating at 405 nm are thus proposed.

scholarly journals Triazine-Based Type-II Photoinitiating System for Free Radical Photopolymerization: Mechanism, Efficiency, and Modeling

2017 ◽  
Vol 218 (18) ◽  
pp. 1600597 ◽  
Author(s):  
Julien Christmann ◽  
Xavier Allonas ◽  
Christian Ley ◽  
Ahmad Ibrahim ◽  
Céline Croutxé-Barghorn
Keyword(s):  
Free Radical ◽  
Type Ii ◽  
Free Radical Photopolymerization

scholarly journals Lawsone Derivatives as Efficient Photopolymerizable Initiators for Free-Radical, Cationic Photopolymerizations, and Thiol—Ene Reactions

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2015
Author(s):  
Christine Elian ◽  
Vlasta Brezová ◽  
Pauline Sautrot-Ba ◽  
Martin Breza ◽  
Davy-Louis Versace
Keyword(s):  
Free Radical ◽  
Paramagnetic Resonance ◽  
Ene Reactions ◽  
Ene Reaction ◽  
Free Radical Photopolymerization ◽  
Abstraction Reaction ◽  
Epoxy Monomer ◽  
Iodonium Salt ◽  
Epr Spin Trapping ◽  
Electron Paramagnetic

Two new photopolymerizable vinyl (2-(allyloxy) 1,4-naphthoquinone, HNQA) and epoxy (2-(oxiran-2yl methoxy) 1,4-naphthoquinone, HNQE) photoinitiators derived from lawsone were designed in this paper. These new photoinitiators can be used as one-component photoinitiating systems for the free-radical photopolymerization of acrylate bio-based monomer without the addition of any co-initiators. As highlighted by the electron paramagnetic resonance (EPR) spin-trapping results, the formation of carbon-centered radicals from an intermolecular H abstraction reaction was evidenced and can act as initiating species. Interestingly, the introduction of iodonium salt (Iod) used as a co-initiator has led to (1) the cationic photopolymerization of epoxy monomer with high final conversions and (2) an increase of the rates of free-radical polymerization of the acrylate bio-based monomer; we also demonstrated the concomitant thiol–ene reaction and cationic photopolymerizations of a limonene 1,2 epoxide/thiol blend mixture with the HNQA/Iod photoinitiating system.

scholarly journals Design of keto-coumarin based photoinitiator for Free Radical Photopolymerization: Towards 3D printing and photocomposites applications

2021 ◽  
pp. 110559
Author(s):  
Mahmoud Rahal ◽  
Bernadette Graff ◽  
Joumana Toufaily ◽  
Tayssir Hamieh ◽  
Frédéric Dumur ◽  
...  
Keyword(s):  
Free Radical ◽  
3D Printing ◽  
Free Radical Photopolymerization

scholarly journals New, highly versatile bimolecular photoinitiating systems for free-radical, cationic and thiol–ene photopolymerization processes under low light intensity UV and visible LEDs for 3D printing application

RSC Advances ◽  
2020 ◽  
Vol 10 (13) ◽  
pp. 7509-7522 ◽  
Author(s):  
Emilia Hola ◽  
Monika Topa ◽  
Anna Chachaj-Brekiesz ◽  
Maciej Pilch ◽  
Paweł Fiedor ◽  
...  
Keyword(s):  
Free Radical ◽  
3D Printing ◽  
Light Intensity ◽  
Low Light ◽  
Low Light Intensity ◽  
Iodonium Salt ◽  
Methyl Naphthalene

1-Amino-4-methyl-naphthalene-2-carbonitrile derivatives are proposed for the role of photosensitizers of iodonium salt during the photopolymerization processes upon near UV-A and visible ranges.

scholarly journals Development of New High-Performance Biphenyl and Terphenyl Derivatives as Versatile Photoredox Photoinitiating Systems and Their Applications in 3D Printing Photopolymerization Processes

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 827 ◽  
Author(s):  
Tomal ◽  
Pilch ◽  
Chachaj-Brekiesz ◽  
Ortyl
Keyword(s):  
Free Radical ◽  
High Performance ◽  
Theoretical Calculations ◽  
Polymer Networks ◽  
Electrochemical Analysis ◽  
Type Ii ◽  
Long Wave ◽  
Different Types ◽  
Ft Ir ◽  
Iodonium Salt

Novel 2-amino-4-methyl-6-phenyl-benzene-1,3-dicarbonitrile derivatives were proposed as photosensitizes of iodonium salt for a highly effective bimolecular photoinitiating system upon soft irradiation conditions under long-wave ultraviolet (UV-A) and visible light. Remarkably, these structures are highly versatile, allowing access to photoinitiating systems for the free-radical polymerization of acrylates, the cationic photopolymerization of epoxides, glycidyl, and vinyl ethers, the synthesis of interpenetrated polymer networks (IPNs) and the thiol-ene photopolymerization processes. Excellent polymerization profiles for all of the monomers, along with the high final conversions, were obtained. The initiation mechanisms of these bimolecular systems based on the 2-amino-4-methyl-6-phenyl-benzene-1,3-dicarbonitrile derivatives were investigated using the real-time FT-IR technique, steady-state photolysis, fluorescence experiments, theoretical calculations of molecular orbitals, and electrochemical analysis. Moreover, the 2-amino-4-methyl-6-phenyl-benzene-1,3-dicarbonitrile derivatives were investigated as a type II free-radical photoinitiator with amine. It was confirmed that the 2-amino-4-methyl-6-phenyl-benzene-1,3-dicarbonitrile derivatives, in combination with different types of additives, e.g., amine as co-initiator or in the presence of onium salt, can act as a bimolecular photoinitiating system via the photo-reduction or photo-oxidation pathways, respectively.

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