Céline Dietlin’s research while affiliated with Université de Haute-Alsace and other places

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Publications (115)


Phenothiazine-carbazole-based bis oxime esters (PCBOEs) for visible light polymerization
  • Article

August 2024

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34 Reads

European Polymer Journal

Zheng Liu

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Yijun Zhang

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[...]

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Chemical structures of BTXIOXE‐1 to BTXIOXE‐6.
UV/Visible absorption spectra of BTXIOXEs (concentration: 4×10⁻⁵ M) in dichloromethane (DCM) at room temperature.
Steady‐state photolysis of photoinitiating systems in DCM upon LED@405 nm irradiation (110 mW cm⁻²) at room temperature: (a) BTXIOXE‐0, (b) BTXIOXE‐1, (d) BTXIOXE‐0/Iod, (e) BTXIOXE‐1/Iod, (c) compound consumption of BTXIOXEs, and (f) compound consumption of BTXIOXEs with Iod.
Photopolymerization of PEGDA containing different photoinitiating systems: (a) thick samples containing BTXIOXEs under LED@405 nm, (b) thin samples (laminated) containing BTXIOXEs under LED@405 nm, (c) thick samples containing BTXIOXEs/Iod under LED@405 nm, (d) thin samples containing BTXIOXEs/Iod under LED@405 nm, (e) thick samples containing BTXIOXEs/Iod under LED@450 nm, (f) thin samples (laminated) containing BTXIOXEs/Iod under LED@450 nm, (g) thin samples (laminated) containing BTXIOXE under sunlight, and (h) thin samples (laminated) containing BTXIOXE/Iod under sunlight. The concentration of BTXIOXE and BTXIOXE/Iod were controlled at 2.0×10⁻⁶ mol and 2.0×10⁻⁶/4.0×10⁻⁶ (mol/mol) in 1 g PEGDA, respectively. The LED was switched on at t=10 s during photopolymerization for the RT‐FTIR experiments a to f.
ESR spectrum of different initiating systems containing N‐tert‐butyl‐α‐phenylnitrone (PBN) upon irradiation of LED@405 nm: (a) BTXIOXE‐1/Iod/PBN and (b) BTXIOXE‐2/Iod/PBN.

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High Photoinitiating Efficiency of Benzothioxanthene‐Based Oxime Esters in Photopolymerization via Photocleavage and/or Single Electron Transfer under Visible Light and Sunlight
  • Article
  • Full-text available

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.

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High Photoinitiating Efficiency of Benzothioxanthene‐Based Oxime Esters in Photopolymerization via Photocleavage and/or Single Electron Transfer under Visible Light and Sunlight

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.





Figure 12. UV-visible absorption spectra of (a) Cu1BF4, (b) Cu1PF6, (c) Cu2BF4, (d) Cu2PF6 and (e) G1 in dichloromethane.
Figure 23. Polymerization profiles (epoxide function conversion vs. irradiation time) of EPOX upon irradiation with a LED at 405 nm, under air, sample thickness = 1.4 mm; the irradiation starts at 10 Figure 23. Polymerization profiles (epoxide function conversion vs. irradiation time) of EPOX upon irradiation with a LED at 405 nm, under air, sample thickness = 1.4 mm; the irradiation starts at 10 s, 50 mW cm −2 . Photoinitiating systems: (curve a) Cu1BF4/Iod/EDB (0.73/2.0/2.0 w/w/w%), (curve b) Cu5BF4/Iod/EDB (0.63/2.0/2.0 w/w/w%), and (curve c) Iod/EDB (2.0/2.0 w/w%).
Scheme 2. Synthetic routes to Cu1-Cu6.BF4, Cu1-Cu5.PF6. Synthesis of Cu1BF4 (Figure 1). A mixture of [Cu(CH 3 CN) 4 ]BF 4 (310 mg, 1 mmol) and Xantphos (578 mg, 1 mmol, M = 578.62 g/mol) was dissolved in dichloromethane (200 mL). The solution was allowed to stir at room temperature for 1h and a solution of 2,9-diphenyl-1,10-phenanthroline (332 mg, 1 mmol, M = 332.41 g/mol) in DCM (20 mL) was added in one portion. The resulting solution was stirred overnight. The solution was concentrated under reduced pressure so that its volume could be reduced to ca. 5 mL. Diethyl ether was added into the resulting solution, affording red crystals of the complex (934 mg, 88% yield). 1 H-NMR (400 MHz, CDCl 3 ) δ(ppm): 1.67 (s, 3H), 2.19 (s, 3H), 6.54 (s, 6H), 6.51-6.60 (m, 6H), 6.70-6.96 (m, 10H), 7.02-7.12 (m, 6H), 7.38 (dd, 4H, J = 17.6, 7.2 Hz), 7.59 (d, 2H, J = 7.5 Hz), 8.10-8.30 (m, 4H), 8.55 (d, 4H, J = 7.5 Hz); 13 C-NMR (101 MHz, CDCl 3 ) δ(ppm): 26.23, 32.86, 122.28, 122.83, 124.45, 124.83, 125.10, 125.35, 126.39, 126.60, 126.67, 126.74, 126.81, 127.36, 127.61, 127.86, 128.22, 129.31, 130.88, 130.98, 131.09, 135.34, 150.99, 151.92; 19 F-NMR (CDCl 3 ) δ: −153.9; 31 P-NMR (CDCl 3 ) δ: −14.43; HRMS (ESI MS) m/z: theor: 1060.2567 found: 1060.2565 (M + detected).
Maximum absorption wavelengths (λmax), extinction coefficients at λmax and at the nominal emission wavelength of the LED (405 nm) for Cu3BF4, Cu3PF6, Cu4BF4 and Cu4PF6 in acetonitrile and for Cu5BF4, Cu5PF6, and Cu6 in dichloromethane.
Panchromatic Copper Complexes for Visible Light Photopolymerization

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.


Development of a Borane–(Meth)acrylate Photo‐Click Reaction

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.


Development of a Borane–(Meth)acrylate Photo‐Click Reaction

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.


Citations (74)


... [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. ...

Reference:

High Photoinitiating Efficiency of Benzothioxanthene‐Based Oxime Esters in Photopolymerization via Photocleavage and/or Single Electron Transfer under Visible Light and Sunlight
Naphthoquinone-Based Oxime Esters for Free Radical Photopolymerization under Sunlight or a Blue Light-Emitting Diode
  • Citing Article
  • 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). ...

Panchromatic Copper Complexes for Visible Light Photopolymerization

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. ...

Development of a Borane–(Meth)acrylate Photo‐Click Reaction

... [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). ...

Concomitant initiation of radical and cationic polymerisations using new copper complexes as photoinitiators: Synthesis and characterisation of acrylate/epoxy interpenetrated polymer networks
  • Citing Article
  • 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]. ...

Donor-acceptor-donor structured thioxanthone derivatives as visible photoinitiators
  • Citing Article
  • 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]. ...

Photoinitiator-Catalyst Systems Based on Meta-Terphenyl Derivatives as Photosensitisers of Iodonium and Thianthrenium Salts for Visible Photopolymerization in 3D Printing Processes

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. ...

Thermal Initiators as Additives for Photopolymerization of Methacrylates upon Blue Light

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. ...

New Phosphine Oxides as High Performance Near- UV Type I Photoinitiators of Radical Polymerization

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. ...

In-silico rational design by molecular modeling of new ketones as photoinitiators in three-component photoinitiating systems: application on 3D printing
  • Citing Article
  • 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]. ...

Polymeric Iodonium Salts to Trigger Free Radical Photopolymerization

Macromolecular Rapid Communications