August 2024
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34 Reads
European Polymer Journal
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August 2024
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34 Reads
European Polymer Journal
July 2024
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127 Reads
In this work, six benzothioxanthene‐based oxime esters were employed as photoinitiators for photopolymerization under visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating systems with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene‐based oxime esters were systematically tested under excitation with low‐intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, parallel to the polymerization tests done under artificial light, the different benzothioxanthene‐based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures.
July 2024
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62 Reads
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1 Citation
European Polymer Journal
June 2024
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76 Reads
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1 Citation
Angewandte Chemie
In this work, six benzothioxanthene‐based oxime esters were employed as photoinitiators for photopolymerization with visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating system with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene‐based oxime esters were systematically tested under excitation with low‐intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, to the polymerization tests done under artificial light, different benzothioxanthene‐based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures.
February 2024
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67 Reads
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5 Citations
Industrial & Engineering Chemistry Research
January 2024
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17 Reads
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1 Citation
Polymer Chemistry
Currently, there are only a few industrial and academic works focused on photopolymerization conducted under natural light.
January 2024
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39 Reads
Polymer Chemistry
In this work, a series of sixteen asymmetrically substituted bis-oxime esters CCCBOEs bearing different substituents on the oxime ester sides were designed as Type I photoinitiators for photopolymerization experiments done...
August 2021
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343 Reads
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23 Citations
Photochem
In this work, eleven heteroleptic copper complexes were designed and studied as photoinitiators of polymerization in three-component photoinitiating systems in combination with an iodonium salt and an amine. Notably, ten of them exhibited panchromatic behavior and could be used for long wavelengths. Ferrocene-free copper complexes were capable of efficiently initiating both the radical and cationic polymerizations and exhibited similar performances to that of the benchmark G1 system. Formation of acrylate/epoxy IPNs was also successfully performed even upon irradiation at 455 nm or at 530 nm. Interestingly, all copper complexes containing the 1,1′-bis(diphenylphosphino)ferrocene ligand were not photoluminescent, evidencing that ferrocene could efficiently quench the photoluminescence properties of copper complexes. Besides, these ferrocene-based complexes were capable of efficiently initiating free radical polymerization processes. The ferrocene moiety introduced in the different copper complexes affected neither their panchromatic behaviors nor their abilities to initiate free radical polymerizations.
June 2021
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85 Reads
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11 Citations
In the development of 3D printing fuels, there is a need for new photoinitiating systems working under mild conditions and/or leading to polymers with new and/or enhanced properties. In this context, we introduce herein N‐heterocyclic carbene–borane complexes as reagents for a new type of photo‐click reaction, the borane–(meth)acrylate click reaction. Remarkably, the higher bond number of boranes relative to thiols induced an increase of the network density associated with faster polymerization kinetics. Solid‐state NMR evidenced the strong participation of the boron centers on the network properties, while DMA and AFM showed that the materials exhibit improved mechanical properties, as well as reduced solvent swelling.
May 2021
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98 Reads
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2 Citations
Angewandte Chemie
N-Heterocyclic carbene–borane complexes can lead to a photochemically triggered borane–acrylate click reaction, a new type of photo-click reaction. Because boranes have three substituents they can participate to cross-linking, unlike thiols in thiol–(meth)acrylate reactions. This generates materials with improved mechanical properties. Abstract In the development of 3D printing fuels, there is a need for new photoinitiating systems working under mild conditions and/or leading to polymers with new and/or enhanced properties. In this context, we introduce herein N-heterocyclic carbene–borane complexes as reagents for a new type of photo-click reaction, the borane–(meth)acrylate click reaction. Remarkably, the higher bond number of boranes relative to thiols induced an increase of the network density associated with faster polymerization kinetics. Solid-state NMR evidenced the strong participation of the boron centers on the network properties, while DMA and AFM showed that the materials exhibit improved mechanical properties, as well as reduced solvent swelling.
... [1,2] According to the free radical photopolymerization (FRP) mechanism, free radical photoinitiators can be classified as Type I (photocleavage) and as Type II (hydrogen abstraction) initiators. [3][4][5][6][7][8] Benefiting from the ongoing efforts for developing visible light photoinitiating systems, numerous photoinitiating systems of innovative compositions have been developed in recent years, consisting of a photoinitiator absorbing light and optionally additives enabling to generate the initiating species. In these systems, a single electron transfer (SET) event can be observed between photoinitiators and additives (electron donor vs. electron acceptor), and active species can be generated during this process to initiate photopolymerization. [9][10][11] In this field, the most popular approach consists in using an electron-rich photosensitizer that will promote in the excited state a photoinduced electron transfer towards an electron-deficient onium salt (most of the time an iodonium salt), that will be reduced, generating an instable structure that will immediately decompose and generate the desired initiating radicals. ...
February 2024
Industrial & Engineering Chemistry Research
... [238][239][240][241][242][243][244][245][246][247][248] A similar easiness of chemical modifications can also be mentioned for carbazole [152,206,207,[249][250][251][252][253][254][255][256][257][258][259] and triphenylamine [260,261], but also for other popular scaffolds for the design of photoinitiators such as naphthalimide, [97,227,228,[262][263][264][265][266][267][268][269][270][271][272][273][274][275][276][277] benzophenone, [278][279][280][281][282][283][284][285] acridine-1,8-dione, [286][287][288] pyrene, [289][290][291][292][293][294][295][296][297] thioxanthones, [298][299][300][301] iridium complexes, [302][303][304][305][306][307][308][309] or copper complexes. [310][311][312][313][314][315][316][317][318][319][320][321][322][323][324][325][326][327] In these different cases, interesting structure/performance relationship could be established. Due to the presence of phenothiazine, a broader absorption spectrum could be determined for C63, the absorption extending up to 560 nm contrarily to 500 nm for C61 and C62 (See Figure 63). ...
August 2021
Photochem
... Notably, transfer of more than one hydrogen atom from the same Lewis base-borane molecule has also been reported. [36] On the other hand, replacing the hydrogen atoms of Lewis base-borane by deuterium atoms makes it a deuterium atom donor instead. [37] In 2022, our group reported a sequential dechlorinative coupling of activated trichloromethyl groups to construct all-carbon quaternary centers using different Lewis-base boryl radicals as promoters. ...
June 2021
... [238][239][240][241][242][243][244][245][246][247][248] A similar easiness of chemical modifications can also be mentioned for carbazole [152,206,207,[249][250][251][252][253][254][255][256][257][258][259] and triphenylamine [260,261], but also for other popular scaffolds for the design of photoinitiators such as naphthalimide, [97,227,228,[262][263][264][265][266][267][268][269][270][271][272][273][274][275][276][277] benzophenone, [278][279][280][281][282][283][284][285] acridine-1,8-dione, [286][287][288] pyrene, [289][290][291][292][293][294][295][296][297] thioxanthones, [298][299][300][301] iridium complexes, [302][303][304][305][306][307][308][309] or copper complexes. [310][311][312][313][314][315][316][317][318][319][320][321][322][323][324][325][326][327] In these different cases, interesting structure/performance relationship could be established. Due to the presence of phenothiazine, a broader absorption spectrum could be determined for C63, the absorption extending up to 560 nm contrarily to 500 nm for C61 and C62 (See Figure 63). ...
April 2021
European Polymer Journal
... In this work, we synthesized a solution mask molecule (E)-1-cyclohexyl-3-(1H-pyrrol-2-yl)prop-2-en-1-one(E-CPP), which indicates a broader absorption region and a larger molar extinction coefficient(ε) to mask the BAPO/ITX [32][33][34][35] initiation system, so that the photocurable materials containing E-CPP and BAPO/ITX can be stored in sunlight for more than 7 days. Under the high-intensity irradiation of LED@405 nm, E-CPP was first converted into Z-CPP, and then gradually bleached [36][37][38][39][40][41][42]. ...
November 2020
Polymer Chemistry
... Appropriate design of the photosensitiser makes it possible to provide the desired donor properties of amines while limiting their ability to be protonated. An example of such a design is the developed terphenyl core [76,77]. Due to the arrangement of electronacceptor groups in the vicinity of the amine group, a photosensitiser capable of efficiently photoinitiating cationic polymerisation in a photoinitiating system with iodonium salt was obtained [78]. ...
June 2020
Polymer Chemistry
... Given that blue light falls within the visible spectrum, it presents the advantages of controllability of the emission range and energy consumption when LEDs are used as the light sources, and a better light penetration can be obtained compared to UV light. [39,40] Opting for OXEs for the FRP of TMPTA under blue light holds merit, especially when compared to the commercially available diphenyl(2,4,6trimethylbenzoyl)phosphine oxide (TPO) which lacks of absorption at 455 nm. [15] However, to date, there is currently only one report concerning the FRP of TMPTA using OXEs under blue light. ...
May 2020
Coatings
... [15,16] Similar strategies involving other electron-donating acyl groups have been employed to enhance the absorption wavelength of both MAPOs and BAPOs. [17][18][19][20][21][22][23][24][25] Interestingly, Cowley and co-workers reported the synthesis of the first cyclo-bis(acyl)phosphine oxide (CBAPO) in 1987, 2phenyl-isophosphindole-1,3-dione oxide (C, Figure 1b), which represents a novel subtype of BAPOs. [26] However, investigations into CBAPO derivatives has thus far been primarily focused on their application as optoelectronic functional materials. ...
April 2020
Molecules
... That is why this technique is widely used and constantly modernized [4][5][6][7][8]. Nowadays, its most popular applications are medicine, including dentistry, coating, and 3D/4D printing [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Due to low energy consumption, a lack of solvents, and a high rate at ambient temperatures, photopolymerization is considered an ecological method compared to other techniques. ...
February 2020
Polymer Chemistry
... Pojman "rediscovered" frontal polymerization with methacrylic acid in 1991 [3]. Frontal processes can be supported by a variety of polymerization mechanisms, such as ring-opening metathesis polymerization [4][5][6], free-radical polymerization [7][8][9], and cationic/anionic polymerization [10][11][12][13]. The rate at which the polymer front propagates, and the maximum front temperature are affected by parameters such as the selection of monomer, initiator/catalyst, and additives [14,15]. ...
February 2020
Macromolecular Rapid Communications