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37 results on '"Graff, Bernadette"'

11. Low‐Migration Compounds with Amine Functionality as Coinitiators of Radical Polymerization.

Author

Chen, Hong, Schmitt, Michael, Graff, Bernadette, Morlet‐Savary, Fabrice, Hahn, Christoph, Kelch, Hauke, Maletz, Reinhard, Willner, Alexander, and Lalevée, Jacques

Subjects
ELECTRON paramagnetic resonance, AROMATIC amines, MOLECULAR orbitals, DENTAL materials, FREE radicals
Abstract

The utilization of two‐component systems comprising camphorquinone (CQ) and aromatic amines has become prevalent in the photopolymerization. However, there are still concerns about the safety of this CQ/amine system, mainly because of the toxicity associated with the leaching of aromatic amines. In light of these concerns, this study aims to develop novel coinitiator combinations featuring CQ and amines which cannot be leached out of materials, enabling free radical polymerization of representative dentalmethacrylate resins under blue light irradiation. This approach involves the initial design and analysis of hydrogen donors with low C─H bond dissociation energy through molecular modeling. Subsequently, copolymerizable methacrylate functional groups are incorporated via chemical modification, allowing it to act as both coinitiator and copolymerization monomer to achieve low migrationand leachability properties. This work presents, for the first time, the synthesis of the innovative coinitiator and compares its performance with the benchmark CQ/ethyl‐4‐dimethylaminobenzoate (EDB)‐based photoinitiation system (PIS). The results demonstrate the effectiveness of the newly proposed PIS. Finally, an in‐depth investigation is conducted into the reaction mechanism associated with this PIS through molecular orbital calculations and electron spin resonance studies. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Photoinitiation Mechanisms of Novel Phenothiazine‐Based Oxime and Oxime Esters Acting as Visible Light Sensitive Type I and Multicomponent Photoinitiators

Author

Noon, Adel, primary, Hammoud, Fatima, additional, Graff, Bernadette, additional, Hamieh, Tayssir, additional, Toufaily, Joumana, additional, Morlet‐Savary, Fabrice, additional, Schmitt, Michael, additional, Bui, Thanh‐Tuan, additional, Rico, Alexandre, additional, Goubard, Fabrice, additional, Péralta, Sébastien, additional, Dumur, Frédéric, additional, and Lalevée, Jacques, additional

Published
2023
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16. Bio-based captodative ligands for redox polymerization of Elium® thermoplastic composites under mild conditions.

Author

Giacoletto, Nicolas, Le Dot, Marie, Cherif, Hizia, Morlet-Savary, Fabrice, Graff, Bernadette, Monnier, Valérie, Gigmes, Didier, Dumur, Frédéric, Olleik, Hamza, Maresca, Marc, Gerard, Pierre, Nechab, Malek, and Lalevée, Jacques

Subjects
THERMOPLASTIC composites, LIGAND exchange reactions, REDOX polymers, POLYMERIZATION, LIGANDS (Chemistry), OXIDATION-reduction reaction, REDUCTION potential
Abstract

Thermoplastic polymers obtained from resins such as Elium® combine desirable properties, including recyclability/reusability and excellent thermomechanical performances, at a relatively affordable cost. Nevertheless, their polymerization often requires a high amount of energy and/or involves hazardous chemical compounds. To address this last point, a series of bio-based captodative ligands was designed and synthesized in order to replace controversial phosphine oxides commonly used in low-energy initiating systems but suffering from toxicity issues. By using these captodative ligands, the curing time required for the polymerization of Elium® could be reduced from more than one hour to a mere 10 minutes. To gain a deeper insight into the redox mechanism involved during the polymerization process, the redox properties of a series of manganese(III) complexes containing different captodative ligands have been investigated employing cyclic voltammetry. It has been demonstrated that ligand exchange reactions induced by using the captodative (or push–pull) ligands possessing both electron-donating and electron-withdrawing groups had a significant impact on the reduction potential of the manganese(III) complexes. The reduction potential significantly changed depending on the type of heteroatom atom (X = O, S) and substituent included in the scaffold of the captodative ligands. [ABSTRACT FROM AUTHOR]

Published
2023
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17. The Blue‐LED‐Sensitive Naphthoquinone‐Imidazolyl Derivatives as Type II Photoinitiators of Free Radical Photopolymerization

Author

Borjigin, Timur, primary, Schmitt, Michael, additional, Giacoletto, Nicolas, additional, Rico, Alexandre, additional, Bidotti, Hugo, additional, Nechab, Malek, additional, Zhang, Yijun, additional, Graff, Bernadette, additional, Morlet‐Savary, Fabrice, additional, Xiao, Pu, additional, Dumur, Frédéric, additional, and Lalevée, Jacques, additional

Published
2023
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23. Symmetric Iodonium Salts Based on Benzylidene as One-Component Photoinitiators for Applications in 3D Printing

Author

Petko, Filip, primary, Galek, Mariusz, additional, Hola, Emilia, additional, Topa-Skwarczyńska, Monika, additional, Tomal, Wiktoria, additional, Jankowska, Magdalena, additional, Pilch, Maciej, additional, Popielarz, Roman, additional, Graff, Bernadette, additional, Morlet-Savary, Fabrice, additional, Lalevee, Jacques, additional, and Ortyl, Joanna, additional

Published
2022
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24. Investigation of pyrene vs Anthracene-based oxime esters:Role of the excited states on their polymerization initiating abilities

Author

Rahal, Mahmoud, Bidotti, Hugo, Duval, Sylvain, Graff, Bernadette, Hamieh, Tayssir, Toufaily, Joumana, Dumur, Frédéric, Lalevée, Jacques, Université de Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UCCS Équipe Catalyse Supramoléculaire, Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181, Institut de Science des Matériaux de Mulhouse (IS2M), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Lebanese University [Beirut] (LU), Institut de Chimie Radicalaire (ICR), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and Dumur, Frederic

Subjects
[CHIM.POLY] Chemical Sciences/Polymers, Free Radical Photopolymerization, [CHIM.POLY]Chemical Sciences/Polymers, Polymers and Plastics, Anthracene, Pyrene, Organic Chemistry, Materials Chemistry, General Physics and Astronomy, Oxime Ester, Light-Emitting Diodes (LED), 3D printing, Light -Emitting Diodes (LED)
Abstract

International audience; In this work, two series of oxime esters (OXE) based on Pyrene and Anthracene chromophores were synthesized and tested as Type Ⅰ photoinitiators for the Free Radical Photopolymerization (FRP) under visible irradiation at 405 nm using light-emitting diodes (LED) as the irradiation source. Interestingly, the two series of oxime esters only differ by the nature of the substituents connected to the oxime ester functional group. As a result of this modification, the reactivity of the different compounds only depends on the rate of decomposition from their excited states as well as the reactivity of the generated radicals. Remarkably, the 18 Pyrene-based OXEs (Py-OXE) and 17 Anthracene-based OXEs (An-OXE) were never synthesized prior to this work. Pyrene and Anthracene chromophores were selected as benchmark structures reacting mainly from their first excited singlet (S1) and triplet (T1) states, respectively. This will allow to shed some light on the excited states responsible of the cleavage of OXEs. Therefore, originality of this study relies in the difference of the initiation ability between these two families. In fact, the results showed that Py-OXEs (0.5% w) are the most efficient systems compared to An-OXEs, so that higher final conversions and rates of polymerization could be obtained with Py-OXEs. Influence of the OXE structure (both chromophores and leaving groups) is discussed on the basis of different characterization techniques such as: UV-visible absorption spectroscopy, photolysis experiments, real-time Fourier transform infrared spectroscopy (RT-FTIR), stationary fluorescence and time-2 resolved fluorescence. Therefore, a global mechanism is finally provided based on the complementary characterization data. Oxime ester derivatives were also tested under air for the generation of 3D patterns (by Direct Laser Write DLW) using a diode laser at 405 nm.

Published
2022
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26. Novel Copper Complexes as Visible Light Photoinitiators for the Synthesis of Interpenetrating Polymer Networks (IPNs)

Author

Rahal, Mahmoud, Noirbent, Guillaume, Graff, Bernadette, Toufaily, Joumana, Hamieh, Tayssir, Gigmes, Didier, Dumur, Frédéric, Lalevée, Jacques, Rahal, Mahmoud, Noirbent, Guillaume, Graff, Bernadette, Toufaily, Joumana, Hamieh, Tayssir, Gigmes, Didier, Dumur, Frédéric, and Lalevée, Jacques

Abstract

This work is devoted to the study of two copper complexes (Cu) bearing pyridine ligands, which were synthesized, evaluated and tested as new visible light photoinitiators for the free radical photopolymerization (FRP) of acrylates functional groups in thick and thin samples upon light-emitting diodes (LED) at 405 and 455 nm irradiation. These latter wavelengths are considered to be safe to produce polymer materials. The photoinitiation abilities of these organometallic compounds were evaluated in combination with an iodonium (Iod) salt and/or amine (e.g., N-phenylglycine-NPG). Interestingly, high final conversions and high polymerization rates were obtained for both compounds using two and three-component photoinitiating systems (Cu1 (or Cu2)/Iodonium salt (Iod) (0.1%/1% w/ w) and Cu1 (or Cu2)/Iod/amine (0.1%/1%/1% w/ w/ w)). The new proposed copper complexes were also used for direct laser write experiments involving a laser diode at 405 nm, and for the photocomposite synthesis with glass fibers using a UV-conveyor at 395 nm. To explain the obtained polymerization results, different methods and characterization techniques were used: steady-state photolysis, real-time Fourier transform infrared spectroscopy (RT-FTIR), emission spectroscopy and cyclic voltammetry.

Published
2022

32. Sunlight Induced Polymerization Photoinitiated by Novel Push–Pull Dyes: Indane‐1,3‐Dione, 1H‐Cyclopenta[b]Naphthalene‐1,3(2H)‐Dione and 4‐Dimethoxyphenyl‐1‐Allylidene Derivatives

Author

Sun, Ke, primary, Pigot, Corentin, additional, Zhang, Yijun, additional, Borjigin, Timur, additional, Morlet‐Savary, Fabrice, additional, Graff, Bernadette, additional, Nechab, Malek, additional, Xiao, Pu, additional, Dumur, Frédéric, additional, and Lalevée, Jacques, additional

Published
2022
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35. Effect of the Steric Hindrance and Branched Substituents on Visible Phenylamine Oxime Ester Photoinitiators: Photopolymerization Kinetics Investigation through Photo‐DSC Experiments.

Author

Lee, Zhong‐Han, Huang, Tung‐Liang, Hammoud, Fatima, Chen, Ching‐Chin, Hijazi, Akram, Graff, Bernadette, Lalevée, Jacques, and Chen, Yung‐Chung

Subjects
ELECTRON paramagnetic resonance spectroscopy, STERIC hindrance, ANILINE, OXIMES, PHOTOPOLYMERIZATION, ELECTRON paramagnetic resonance, ESTERS, TRIPHENYLAMINE
Abstract

In this work, free radical photopolymerization (FRP) kinetics for series of different phenylamine oxime ester structures (DMA–P, DEA–P, DMA–M, TP–2P, TP–2M and TP–3M) was investigated. Steric hindrance and branched substituents were prepared to realize the corresponding electronic and photopolymerization effects. The photophysical, electrochemical, thermal properties and radical concentration were investigated by UV‐visible spectroscopy, cyclic voltammetry (CV), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR). Furthermore, the structure–reactivity relationships were also studied in detail through photo‐DSC experiment. We demonstrate that the introduction of alkyl chains and/or numbers of oxime esters affects significantly the photoreactivity. Under the same weight ratio of formulation and irradiated condition, TP–3M containing three oxime esters in its structure and methyl group in the periphery exhibits the highest double‐bond conversion efficiency. TP–3M‐based formulation also shows a wide operation window under different contents and light intensities. Importantly, the photoreactivity of the TP–3M‐based system was found to be better than the commercial photoinitiator (OXE–01) under LED@405 nm at a low concentration. This work could provide some significance to the design of oxime esters with enhanced photoreactivity. [ABSTRACT FROM AUTHOR]

Published
2022
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