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4. Controlling photopolymerization reaction in layer‐by‐layer photopolymerization in 3D printing.

Author

Allonas, Xavier, Hammouda, Ben, Métral, Boris, Goldbach, Emile, Schuller, Anne‐Sophie, Ley, Christian, and Croutxé‐Barghorn, C.Céline

Subjects
RAMAN microscopy, THREE-dimensional printing, INFRARED spectroscopy, CONFOCAL microscopy, PHOTOPOLYMERIZATION
Abstract

Today, controlling the photopolymerization process during the 3D printing in vat photopolymerization is a key challenge. In this work, it is shown that using a relatively limited set of parameter, it is possible to estimate key factors involved in such process. On the basis of 16 formulations containing different concentrations of photoinitiator and UV filter, attempt was made to rationalize the photonic parameters used in the 3D printing process, that is, the depth of penetration Dp and the critical energy Ec. It is shown that the experimental Dp values can be correlated with calculated ones from Bouguer–Beer–Lambert law. Real‐time Fourier‐transform infrared spectroscopy (RT‐FTIR) experiments were performed under similar conditions as in 3D printing. The conversion profiles were used to estimate the Ec values. The limits of this approach was discussed as a function of the UV filter concentration. Finally, the RT‐FTIR curves are exploited to predict the in‐depth conversion of the different 3D printed layers and compared to experimental results obtained by confocal Raman microscopy. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Water safety attitudes, risk perception, experiences, and education for households impacted by the 2018 Camp Fire, California

Author

Odimayomi, Tolulope O., Proctor, Caitlin R., Wang, Qi Erica, Sabbaghi, Arman, Peterson, Kimberly S., Yu, David J., Lee, Juneseok, Shah, Amisha D., Ley, Christian J., Noh, Yoorae, Smith, Charlotte D., Webster, Jackson P., Milinkevich, Kristin, Lodewyk, Michael W., Jenks, Julie A., Smith, James F., and Whelton, Andrew J.

Published
2021
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12. Legionella pneumophila occurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic.

Author

Dowdell, Katherine S., Healy, Hannah Greenwald, Joshi, Sayalee, Grimard-Conea, Marianne, Pitell, Sarah, Yang Song, Ley, Christian, Kennedy, Lauren C., Vosloo, Solize, Linxuan Huo, Haig, Sarah-Jane, Hamilton, Kerry A., Nelson, Kara L., Pinto, Ameet, Prévost, Michèle, Proctor, Caitlin R., Raskin, Lutgarde, Whelton, Andrew J., Garner, Emily, and Pieper, Kelsey J.

Published
2023
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15. Legionella pneumophila occurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

Author

Dowdell, Katherine, Greenwald, Hannah, Joshi, Sayalee, Grimard-Conea, Marianne, Pitell, Sarah, Song, Yang, Ley, Christian, Kennedy, Lauren C, Vosloo, Solize, Huo, Linxuan, Haig, Sarah‐Jane, Hamilton, Kerry A., Nelson, Kara L., Pinto, Ameet J., Prévost, Michèle, Proctor, Caitlin R., Raskin, Lutgarde, Whelton, Andrew J., Garner, Emily, Pieper, Kelsey J., Rhoads, William J., Dowdell, Katherine, Greenwald, Hannah, Joshi, Sayalee, Grimard-Conea, Marianne, Pitell, Sarah, Song, Yang, Ley, Christian, Kennedy, Lauren C, Vosloo, Solize, Huo, Linxuan, Haig, Sarah‐Jane, Hamilton, Kerry A., Nelson, Kara L., Pinto, Ameet J., Prévost, Michèle, Proctor, Caitlin R., Raskin, Lutgarde, Whelton, Andrew J., Garner, Emily, Pieper, Kelsey J., and Rhoads, William J.

Abstract

In spring 2020, numerous buildings were closed or operated at reduced occupancies to slow the spread of COVID-19. An unintended consequence of these social distancing measures was a reduction in water demand in many buildings. Concerns arose that contaminants associated with water stagnation, such as Legionella pneumophila, could become prevalent. To investigate the potential public health risk associated with L. pneumophila, samples from 26 reduced-occupancy buildings in 11 cities in the United States, Canada, and Switzerland were analyzed for L. pneumophila using liquid culture (Legiolert, n = 258) and DNA-based methods (qPCR/ddPCR, n = 138). L. pneumophila culture-positivity was largely associated with five buildings, each of which had specific design or operational deficiencies commonly associated with L. pneumophila occurrence. Samples from buildings with free chlorine residual disinfection had higher culture-positivity (37%) than samples from buildings with chloramine (1%). Additionally, 78% of culture-positive samples occurred when the disinfectant residual was ≤0.1 mg L−1 Cl2 and only three free chlorine samples were culture-positive when the disinfectant residual was >0.2 mg L−1 as Cl2. Although overall sample positivity using culture- and DNA-based methods was equivalent (34% vs. 35%), there was disagreement between the methods in 13% of samples (n = 18 of 138). Few buildings reported any water management activities, and L. pneumophila concentrations in flushed samples were occasionally greater than in first-draw samples. This study provides insight into how building plumbing characteristics and water management practices contribute to L. pneumophila occurrence during low water use periods and can inform targeted prevention and mitigation efforts.

Published
2023

21. UV Inactivation of Common Pathogens and Surrogates Under 222 nm Irradiation from KrCl* Excimer Lamps.

Author

Ma, Ben, Bright, Kelly, Ikner, Luisa, Ley, Christian, Seyedi, Saba, Gerba, Charles P., Sobsey, Mark D., Piper, Patrick, and Linden, Karl G.

Subjects
ULTRAVIOLET lamps, LAMPS, BACTERIAL inactivation, WATER disinfection, PATHOGENIC microorganisms, ULTRAVIOLET radiation
Abstract

Germicidal ultraviolet (UV) devices have been widely used for pathogen disinfection in water, air, and on food and surfaces. Emerging UV technologies, like the krypton chloride (KrCl*) excimer emitting at 222 nm, are rapidly gaining popularity due to their minimal adverse effects on skin and eyes compared with conventional UV lamps emitting at 254 nm, opening opportunities for UV disinfection in occupied public spaces. In this study, inactivation of seven bacteria and five viruses, including waterborne, foodborne and respiratory pathogens, was determined in a thin‐film aqueous solution using a filtered KrCl* excimer emitting primarily at 222 nm. Our results show that the KrCl* excimer can effectively inactivate all tested bacteria and viruses, with most microorganisms achieving more than 4‐log (99.99%) reduction with a UV dose of 10 mJ cm−2. Compared with conventional UV lamps, the KrCl* excimer lamp exhibited better disinfection performance for viruses but was slightly less effective for bacteria. The relationships between UV sensitivities at 222 and 254 nm for bacteria and viruses were evaluated using regression analysis, resulting in factors that could be used to estimate the KrCl* excimer disinfection performance from well‐documented UV kinetics using conventional 254 nm UV lamps. This study provides fundamental information for pathogen disinfection when employing KrCl* excimers. [ABSTRACT FROM AUTHOR]

Published
2023
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22. Optimization of a Safranine O three-component photoinitiating system for use in holographic recording

Author

Ibrahim, Ahmad, El Fouhaili, Bandar, Yong, Aurelie Chan, Ley, Christian, Allonas, Xavier, and Carre, Christiane

Subjects
Photopolymers -- Chemical properties -- Research, Coloring matter -- Chemical properties -- Research, Chemistry
Abstract

The coupling between a holographic resin, combining multiple monomers and additives, with photoinitiating systems (PIS) is not straightforward. In this paper, a classic PIS based on Safranine O ([SFH.sup.+]) as dye, an amine (ethyl-4-(dimethylamino) benzoate) as electron donor, and a triazine derivative (2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine) as electron acceptor for holographic recording was studied using time-resolved spectroscopic experiments. By taking into account the viscosity of the matrix, a method to evaluate the overall quantum yield of radicals released is proposed and the contribution of singlet and triplet excited states of [SFH.sup.+] in the formation of radicals is evaluated. Then the corresponding photopolymerization efficiencies of the PIS, studied by real-time FTIR, are compared with holographic recording experiments: this system allows the formation of a hologram with high diffraction efficiency (0.9) in 3 s of irradiation time. It is shown that besides holographic resin formulation, the photochemistry of PIS also impacts the hologram formation. Key words: photoinitiating system, laser spectroscopy, photopolymerization, holographic recording. Il n'est pas facile d'effectuer le couplage entre une resine holographique, combinant plusieurs monomeres et additifs, et des systemes de photoamorcage. Dans le present article, nous avons etudie un systeme de photoamorcage a base de Safranine O ([SFH.sup.+]) comme colorant, une amine (ethyl-4-(dimethylamino)benzoate) comme electrodonneur et un derive de triazine (2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine) comme electroaccepteur pour effectuer l'enregistrement holographique au moyen d'experiences spectroscopiques a resolution temporelle. En tenant compte de la viscosite de la matrice, nous avons propose une methode d'evaluation du rendement quantique global des radicaux formes et evalue la contribution des etats excites singulet et triplet de la [SFH.sup.+] dans la formation des radicaux. Par la suite, nous avons compare les efficiences de photopolymerisation du systeme de photoamorcage, etudiees par FTIR en temps reel, aux experiences d'enregistrement holographique correspondantes. Les resultats montrent que le systeme permet la formation d'hologrammes avec une efficience de diffraction elevee (0,9) en une periode d'irradiation de trois secondes. En plus de l'effet de la formulation des resines holographiques, nous montrons que la photochimie des systemes de photoamorcage a aussi un effet sur la formation des hologrammes. [Traduit par la Redaction] Mots-cles : systeme de photoamorcage, spectroscopie laser, photopolymerisation, enregistrement holographique., Introduction Photopolymerization technologies have emerged as an attractive curing process over the past decade because they offer a wide variety of advantages and benefits. Most notably, photopolymerization affords spatial and [...]

Published
2015
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23. Legionella pneumophila occurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

Author

Dowdell, Katherine S., primary, Greenwald, Hannah D., additional, Joshi, Sayalee, additional, Grimard-Conea, Marianne, additional, Pitell, Sarah, additional, Song, Yang, additional, Ley, Christian, additional, Kennedy, Lauren C., additional, Vosloo, Solize, additional, Huo, Linxuan, additional, Haig, Sarah-Jane, additional, Hamilton, Kerry A., additional, Nelson, Kara L., additional, Pinto, Ameet, additional, Prévost, Michele, additional, Proctor, Caitlin R., additional, Raskin, Lutgarde M., additional, Whelton, Andrew J., additional, Garner, Emily, additional, Pieper, Kelsey J., additional, and Rhoads, William J., additional

Published
2022
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28. Global Service-Learning: A Systematic Review of Principles and Practices

Author

Hawes, Jason K., primary, Johnson, Rebecca, additional, Payne, Lindsey, additional, Ley, Christian, additional, Grady, Caitlin A., additional, Domenech, Jennifer, additional, Evich, Carly D., additional, Kanach, Andrew, additional, Koeppen, Allison, additional, Roe, Kirsten, additional, Caprio, Audrey, additional, Puente Castro, Jessica, additional, LeMaster, Paige, additional, and Blatchley, Ernest R., additional

Published
2021
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31. Legionella pneumophilaoccurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemicElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3ew00278k

Author

Dowdell, Katherine S., Healy, Hannah Greenwald, Joshi, Sayalee, Grimard-Conea, Marianne, Pitell, Sarah, Song, Yang, Ley, Christian, Kennedy, Lauren C., Vosloo, Solize, Huo, Linxuan, Haig, Sarah-Jane, Hamilton, Kerry A., Nelson, Kara L., Pinto, Ameet, Prévost, Michèle, Proctor, Caitlin R., Raskin, Lutgarde, Whelton, Andrew J., Garner, Emily, Pieper, Kelsey J., and Rhoads, William J.

Abstract

In spring 2020, numerous buildings were closed or operated at reduced occupancies to slow the spread of COVID-19. An unintended consequence of these social distancing measures was a reduction in water demand in many buildings. Concerns arose that contaminants associated with water stagnation, such as Legionella pneumophila, could become prevalent. To investigate the potential public health risk associated with L. pneumophila, samples from 26 reduced-occupancy buildings in 11 cities in the United States, Canada, and Switzerland were analyzed for L. pneumophilausing liquid culture (Legiolert, n= 258) and DNA-based methods (qPCR/ddPCR, n= 138). L. pneumophilaculture-positivity was largely associated with five buildings, each of which had specific design or operational deficiencies commonly associated with L. pneumophilaoccurrence. Samples from buildings with free chlorine residual disinfection had higher culture-positivity (37%) than samples from buildings with chloramine (1%). Additionally, 78% of culture-positive samples occurred when the disinfectant residual was ≤0.1 mg L−1Cl2and only three free chlorine samples were culture-positive when the disinfectant residual was >0.2 mg L−1as Cl2. Although overall sample positivity using culture- and DNA-based methods was equivalent (34% vs.35%), there was disagreement between the methods in 13% of samples (n= 18 of 138). Few buildings reported any water management activities, and L. pneumophilaconcentrations in flushed samples were occasionally greater than in first-draw samples. This study provides insight into how building plumbing characteristics and water management practices contribute to L. pneumophilaoccurrence during low water use periods and can inform targeted prevention and mitigation efforts.

Published
2023
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33. Photoreactions of 3-diazo-3H-benzofuran-2-one, dimerization and hydrolysis of its primary photoproduct, a quinonoid cumulenone: a study by time-resolved optical and infrared spectroscopy

Author

Chiang, Yvonne;, Gaplovsky, Marin, Kresge, A. Jerry, Leung, King Hung, Ley, Christian;, Mac, Marek, Persy, Gabriele, Phillips, David L., Popik, Vladimir V., Rodig, Christoph, Wirz, Jakob, and Zhu, Yu

Subjects
Raman spectroscopy -- Usage, Carbonyl compounds -- Research, Carbonyl compounds -- Chemical properties, Chemistry
Abstract

Identification of cumulenone as the sole primary product of 3-diazo-3H-benzofuran-2-one in solution, its reaction kinetics in aqueous acid and in aprotic solvents is reported. DFT calculations suggest that protonation of 6-(oxoethenylidene)-2, 4-cyclohexadien-1-one on the beta-carbon is accompanied by cyclization to the protonated carbene 2H+.

Published
2003

34. Impacts of Municipal Water–Rainwater Source Transitions on Microbial and Chemical Water Quality Dynamics at the Tap

Author

Ley, Christian J., primary, Proctor, Caitlin R., additional, Jordan, Kathryn, additional, Ra, Kyungyeon, additional, Noh, Yoorae, additional, Odimayomi, Tolulope, additional, Julien, Ryan, additional, Kropp, Ian, additional, Mitchell, Jade, additional, Nejadhashemi, A. Pouyan, additional, Whelton, Andrew J., additional, and Aw, Tiong Gim, additional

Published
2020
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36. Drinking water microbiology in a water-efficient building: stagnation, seasonality, and physicochemical effects on opportunistic pathogen and total bacteria proliferation

Author

Ley, Christian J., primary, Proctor, Caitlin R., additional, Singh, Gulshan, additional, Ra, Kyungyeon, additional, Noh, Yoorae, additional, Odimayomi, Tolulope, additional, Salehi, Maryam, additional, Julien, Ryan, additional, Mitchell, Jade, additional, Nejadhashemi, A. Pouyan, additional, Whelton, Andrew J., additional, and Aw, Tiong Gim, additional

Published
2020
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39. Short-term Organic Carbon Release and Chlorine Disinfectant Decay for Cross-linked Polyethylene (PEX) Plumbing Pipes

Author

Tariq, Miriam, Ley, Christian J., Salehi, Maryam, and Whelton, Andrew J

Subjects
polyethylene, Civil and Environmental Engineering, plastic, Sustainability, education, polycyclic compounds, plumbing, water quality, PEX, Environmental Sciences
Abstract

The use of cross-linked polyethylene (PEX) plumbing pipes has grown in popularity for residential applications. However, PEX pipes can leach organic materials into water that can enable biofilm growth, cause off-tastes and -odors, and may react with disinfectants to form disinfection by-products (DBP). Varied manufacturing processes that are applied to create PEX pipes add to the complexity of understanding organic materials released. In this study, organic carbon release from three PEX pipe brands was monitored for up to five days using a series of stagnation periods. Seven stagnation periods of 1, 2, 4, 8, 24, 72, and 120 hours were conducted at 50 degrees Celsius with varying initial chlorine concentrations for a type A (PEX-a), type B (PEX-b), and type C (PEX-c) brand. Pipes were exposed to chlorinated tap water synthesized in the lab. Water exposed to these pipes was analyzed to determine total organic carbon (TOC), assimilable organic carbon (AOC), total chlorine, and free chlorine concentrations. Results show that all pipe brands had different chlorine decay rates and TOC concentrations. Chlorine residual decayed the slowest and fastest for PEX-A pipes and PEX-C pipes, respectively. Chlorine completely decayed in most pipes by 24 hours when the initial chlorine concentration was 2.0 mg/L. PEX-B leached the most amount of contaminants, with a TOC concentration that far exceeded 2.0 mg/L within 24 hours. AOC concentrations tended to increase over time for all pipes. Future work should include additional brands, aged PEX pipes, different flow conditions, temperatures, and longer stagnation periods.

Published
2018

45. High Performance Photoinitiating Systems for Free Radical Polymerization: Application to Holographic Grating Recording

Author

Ley, Christian, Carré, Christiane, Ibrahim, Ahmad, Allonas, Xavier, Laboratoire de Photochimie et d'Ingénierie Macromoléculaires (LPIM), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-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)-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), Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), Society of Photopolymer Science and Technology, New PIS, Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-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)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)

Subjects
Photochemistry, Holographic recording material, Photocyclic in itiating system, Holography, [CHIM.MATE]Chemical Sciences/Material chemistry, Photopolymer
Abstract

International audience; Photopolymerization reaction can be used in self-developing photopolymerizable resin to recording holographic gratings. In this work, the efficiencies of two and three component photoinitiating system for holographic recording are analyzed in term of photopolymerization and grating diffraction yield kinetics. The selected systems are based on a visible dye, electron donor and electron acceptor. Time resolved and steady state spectroscopic studies of the photoinitiators are presented. This detailed photochemical study outlines the possible existence of photocyclic initiating systems where the dye is regenerated during the photochemical process. To study the impact of photoinitaiting system on the hologram grating formation, diffraction curves are compared to those of monomer to polymer conversion. This work outlines the importance of the photochemistry on fi nal holographic material properties.

Published
2017

46. Optimisation and coupling of high-performance photocyclic initiating systems for efficient holographic materials

Author

Ley, Christian, Carré, Christiane, Ibrahim, Ahmad, Allonas, Xavier, Laboratoire de Photochimie et d'Ingénierie Macromoléculaires (LPIM), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-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)-Centre National de la Recherche Scientifique (CNRS), Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), SPIE, New PIS, Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-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)-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 Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Photoinitiator, Dye, Photochemistry, Holographic recording material, Holography, 3-component photoinitiating systems, Diffraction grating, [CHIM.MATE]Chemical Sciences/Material chemistry, Photopolymerisation, Photopolymer
Abstract

International audience; For fabrication of diffractive optical elements or for holographic data storage, photopolymer materials have turned out to be serious candidates, taking into account their performances such as high spatial resolution, dry processing capability, ease of use, high versatility. From the chemical point of view, several organic materials are able to exhibit refractive index changes resulting from polymerization, crosslinking or depolymerization, such as mixtures of monomers with several reactive functions and oligomers, associated to additives, fillers and to a photoinitiating system (PIS). In this work, the efficiencies of two and three component PIS as holographic recording materials are analyzed in term of photopolymerization kinetics and diffraction yield. The selected systems are based on visible dyes, electron donor and electron acceptor. In order to investigate the influence of the photophysical properties of dye on the holographic recording material performance time resolved and steady state spectroscopic studies of the PIS are presented. This detailed photochemical studies of the PIS outline the possible existence of photocyclic initiating systems (PCIS) where the dye is regenerated during the chemical process. Simultaneously, these visible systems are associated to fluorinated acrylate monomers for the recording of transmission gratings. To get more insight into the hologram formation, gratings' recording curves were compared to those of monomer to polymer conversion obtained by real time Fourier transform infrared spectroscopy. This work outlines the importance of the coupling of the the photochemical reactions and the holographic resin. Moreover the application of the PCIS in holographic recording outlines the importance of the photochemistry on final holographic material properties: here a sensitive material with high diffraction yield is described. Indeed, this work outlines the importance of the coupling between the photochemistry underlying the radicals photogeneration and the holographic resin.

Published
2017

47. Stockage d’informations optiques et photopolymérisation résolue dans l’espace

Author

Carré, Christiane, Ley, Christian, Allonas, Xavier, Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire de Photochimie et d'Ingénierie Macromoléculaires (LPIM), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-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)-Centre National de la Recherche Scientifique (CNRS), Club CMOI - Société Française d'Optique, New PIS, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et Nanosciences Grand-Est (MNGE), and 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)-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)

Subjects
Réseau holographique, Stockage d'informations, Photoamorceur, [CHIM.MATE]Chemical Sciences/Material chemistry, Photopolymérisation
Abstract

National audience; The efficiency of different combinations of dyes, amines as electron donors and electron acceptors for free radical photopolymerization of a mixture of acrylic monomers was studied and optimized, giving rise to efficient holographic gratings.; Différents systèmes photoamorceurs mettant en jeu deux ou trois composants (un colorant et deux co-amorceurs, le premier étant un donneur d’électron et le second un accepteur d’électron) et destinés à la polymérisation d’un mélange d’acrylates sont ici comparés les uns aux autres en tant que support pour le stockage d’informations par holographie. Les 2 ou 3 composants sont un colorant associé à un ou deux co-amorceurs, le premier étant un donneur d’électron et le second un accepteur d’électron.

Published
2017

49. Photochemical Study of a Three‐Component Photocyclic Initiating System for Free Radical Photopolymerization: Implementing a Model for Digital Light Processing 3D Printing.

Author

Metral, Boris, Bischoff, Adrien, Ley, Christian, Ibrahim, Ahmad, and Allonas, Xavier

Subjects
THREE-dimensional printing, FLASH photolysis, PHOTOPOLYMERIZATION, FOURIER transform infrared spectroscopy, PRINTMAKING
Abstract

Vat photopolymerization technologies are promising 3D printing techniques in the field of additive manufacturing, which requires high performance and affordable photoinitiating systems (PIS). In this paper, we introduce a complex PIS based on safranine as photosensitizer and two redox additives. The photocycling mechanism is explored via laser flash photolysis (LFP) and its reactivity is investigated through real‐time Fourier transform infrared spectroscopy (RT‐FTIR). A model which predicts with good accuracy the change in conversion with both time and light intensity is proposed. Cure depth experiments are conducted and the critical energy (Ec) and penetration depth (Dp) are established for the resin used. The relationship between these parameters and the corresponding RT‐FTIR results was highlighted through the role of the conversion at the gel point, allowing optimization of the formulation. Finally, high resolution complex pieces are printed with the resin, whose composition was tailored in accordance with our studies, demonstrating the viability of this PIS in digital light processing (DLP) 3D printing. [ABSTRACT FROM AUTHOR]

Published
2019
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50. Spectro-temporal characterization of the photoactivation mechanism of two new oxidized cryptochrome/photolyase photoreceptors

Author

Brazard, Johanna, Usman, Anwar, Lacobat, Fabien, Ley, Christian, Martin, Monique M., Plaza, Pascal, Mony, Laetitia, Heijde, Marc, Zabulon, Gerald, and Bowler, Chris

Subjects
Flavin adenine dinucleotide -- Chemical properties, Flavin adenine dinucleotide -- Optical properties, Oxidation-reduction reaction -- Analysis, Ultraviolet spectroscopy -- Usage, Chemistry
Abstract

Broadband UV-vis femtosecond absorption spectroscopy is used for studying the photoactivation dynamics of two new flavoproteins (OtCPF1 and OtCPF2) of the cryptochrome photolyase family (CPF), belonging to the green alga Ostreococcus tauri. The transient anisotropy measurements performed on OtCPF2 have displayed good compatibility with the oxidation of the distal tryptophan (W[H.sub.351]) in 340 ps and hence with the overall Brettel-Vos mechanism.

Published
2010

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