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Jacques Lalevée - One of the best experts on this subject based on the ideXlab platform.
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Photopolymerization processes of thick films and in shadow areas: a review for the access to composites
Polymer Chemistry, 2017Co-Authors: Patxi Garra, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Celine Dietlin, Jacques LalevéeAbstract:The Photopolymerization processes are currently associated with thin samples for which the light penetration is good enough to activate the photoinitiator or the photoinitiating system for the entre sample's thickness. The Photopolymerization of very thick films and in shadow areas where the light penetration is inhibited (e.g. in filled, pigmented, and dispersed samples) remains a huge challenge (e.g. for the access to composites). In the present paper, an overview of the different strategies for the Photopolymerization of thick samples is reported. First, strategies based on the optimization of the photonic (light intensity, excitation wavelength, etc.) or chemical (efficiency/reactivity/bleaching of the photoinitiating systems, etc.) parameters are presented that result in a full temporal and spatial control. Then, the main strategies based on propagation/diffusion mechanisms of latent species for the curing beyond the irradiated areas are given (partial loss of spatial resolution and access to shadow areas). Also, dual systems (thermal/ photochemical or photochemical/redox) are described. The state of the art for the access to thick samples by Photopolymerization processes as well as some perspectives are provided.
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Organic Electronics: an El Dorado in the quest of new photoCatalysts as photoinitiators of polymerization
Accounts of Chemical Research, 2017Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:Photoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition for light absorption between the chromophores and other species in the formulation are key parameters drastically affecting the Photopolymerization process. To address these issues, photoinitiating systems operating under low intensity visible light irradiation, in the absence of solvents are highly sought after. In this context, the use of photoredox catalysis can be highly advantageous; that is, photoredox catalysts can provide high reactivities with low catalyst loading, permitting access to high performance photoinitiating systems. However, to act as efficient photoredox catalysts, specific criteria have to be fulfilled. A strong absorption over the visible range, an ability to easily oxidize or reduce as well as sufficient photochemical stability are basic prerequisites to make these molecules desirable candidates for photoredox catalysis. Considering the similarity of requirements between organic electronics and Photopolymerization, numerous materials initially designed for applications in organic electronics have been revisited in the context of Photopolymerization. Organic electronics is a branch of electronics and materials science focusing on the development of semiconductors devoted to three main research fields; organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells (OSCs). The contribution of organic electronics to the field of electronics is important as it paves the way toward cheaper, lighter, and more energy efficient devices. In the present context of Photopolymerization, materials that were investigated as photocatalysts were indifferently organic semiconductors used for transistors, charge-transport materials, and light-emitting materials used in electroluminescent devices or conjugated polymers and small molecule dyes for solar cells. In this Account, we summarize our latest developments in elaborating on photocatalytic systems based on these new classes of compounds. Through an in-depth understanding of the parameters governing their reactivities and our efforts to incorporate these materials into photoinitiating systems, we provide new knowledge and a valuable insight for future prospects.
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organic electronics an el dorado in the quest of new photocatalysts for polymerization reactions
Accounts of Chemical Research, 2016Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:ConspectusPhotoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition f...
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Naphthalic anhydride derivatives: structural effects on their initiating abilities in radical and/or cationic Photopolymerizations under visible light
Journal of Polymer Science Part A: Polymer Chemistry, 2015Co-Authors: Pu Xiao, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Bernadette Graff, Jacques LalevéeAbstract:Only one naphthalic anhydride derivative has been reported as light sensitive photoinitiator, this prompted us to further explore the possibility to prepare a new family of photoinitiators based on this scaffold. Therefore, eight naphthalic Naphthalic anhydride derivatives (ANH1-ANH8) have been prepared and combined with an iodonium salt (and optionally N-vinylcarbazole) or an amine (and optionally 2,4,6-tris(trichloromethyl)-1,3,5-triazine) to initiate the cationic polymerization of epoxides and the free radical polymerization of acrylates under different irradiation sources, that is, very soft halogen lamp (∼ 12 mW cm−2), laser diode at 405 nm (∼1.5 mW cm−2) or blue LED centered at 455 nm (80 mW cm−2). The ANH6 based photoinitiating systems are particularly efficient for the cationic and the radical Photopolymerizations, and even better than that of the well-known camphorquinone based systems. The photochemical mechanisms associated with the chemical structure/Photopolymerization efficiency relationships are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin-trapping techniques.
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Visible light sensitive photoinitiating systems: Recent progress in cationic and radical Photopolymerization reactions under soft conditions
Progress in Polymer Science, 2014Co-Authors: Pu Xiao, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jing Zhang, Mohamad Ali Tehfe, Fabrice Morlet-savary, Bernadette Graff, Jacques LalevéeAbstract:Although there have been many reports on photoinitiating systems adapted to visible lights for radical Photopolymerization, the challenge for the design and development of photoinitiating systems for cationic Photopolymerization or concomitant radical/cationic Photopolymerization (for interpenetrating polymer network IPN synthesis) with visible lights still remains open. Particularly, the recent development of cheap and easily accessible LEDs operating upon soft visible light irradiations has opened new fields for polymer synthesis. Since 2011, many novel photoinitiating systems based on organic and organometallic compounds with excellent visible light absorption have emerged and exhibited outstanding photoinitiating abilities especially for cationic Photopolymerization. In this review, recent progress (mainly from 2011 to early 2014) in applications of photoinitiators and sensitive photoinitiating systems under visible lights are reported. In addition, their relative efficiencies in the Photopolymerization of different monomers are exemplified and discussed.
Frédéric Dumur - One of the best experts on this subject based on the ideXlab platform.
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Recent Advances and Challenges in the Design of Organic Photoacid and Photobase Generators for Polymerizations
Angewandte Chemie International Edition, 2019Co-Authors: Nicolas Zivic, Frédéric Dumur, Didier Gigmes, Paula K. Kuroishi, Andrew P. Dove, Haritz SardonAbstract:Photopolymerization, or the use of light to trigger polymerization, is one of the most exciting technologies for advanced manufacturing of polymers. One of the key components in the Photopolymerization processes is the photoactive compound that absorbs the light, generating the active species that promotes the polymerization and largely determines the final properties of the material. The field of Photopolymerization has been dominated by photoradical generators to mediate radical reactions. In the last decade, to expand the number of polymers that can be prepared by Photopolymerization, intensive research has been devoted to the synthesis and utilization of photoactive molecules that are able to generate a base or an acid upon irradiation. These organic compounds are known to promote not only the ring-opening polymerization of various heterocyclic monomers such as lactones, carbonates, or epoxides but also to trigger the step-growth synthesis of polyurethanes. This Minireview highlights the recent advances in the development of organic photobase and photoacid generators, with the aim of encouraging the wider application of these photoactive compounds in the Photopolymerization area and to expand the use of these polymers in advanced manufacturing processes.
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Photopolymerization processes of thick films and in shadow areas: a review for the access to composites
Polymer Chemistry, 2017Co-Authors: Patxi Garra, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Celine Dietlin, Jacques LalevéeAbstract:The Photopolymerization processes are currently associated with thin samples for which the light penetration is good enough to activate the photoinitiator or the photoinitiating system for the entre sample's thickness. The Photopolymerization of very thick films and in shadow areas where the light penetration is inhibited (e.g. in filled, pigmented, and dispersed samples) remains a huge challenge (e.g. for the access to composites). In the present paper, an overview of the different strategies for the Photopolymerization of thick samples is reported. First, strategies based on the optimization of the photonic (light intensity, excitation wavelength, etc.) or chemical (efficiency/reactivity/bleaching of the photoinitiating systems, etc.) parameters are presented that result in a full temporal and spatial control. Then, the main strategies based on propagation/diffusion mechanisms of latent species for the curing beyond the irradiated areas are given (partial loss of spatial resolution and access to shadow areas). Also, dual systems (thermal/ photochemical or photochemical/redox) are described. The state of the art for the access to thick samples by Photopolymerization processes as well as some perspectives are provided.
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Organic Electronics: an El Dorado in the quest of new photoCatalysts as photoinitiators of polymerization
Accounts of Chemical Research, 2017Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:Photoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition for light absorption between the chromophores and other species in the formulation are key parameters drastically affecting the Photopolymerization process. To address these issues, photoinitiating systems operating under low intensity visible light irradiation, in the absence of solvents are highly sought after. In this context, the use of photoredox catalysis can be highly advantageous; that is, photoredox catalysts can provide high reactivities with low catalyst loading, permitting access to high performance photoinitiating systems. However, to act as efficient photoredox catalysts, specific criteria have to be fulfilled. A strong absorption over the visible range, an ability to easily oxidize or reduce as well as sufficient photochemical stability are basic prerequisites to make these molecules desirable candidates for photoredox catalysis. Considering the similarity of requirements between organic electronics and Photopolymerization, numerous materials initially designed for applications in organic electronics have been revisited in the context of Photopolymerization. Organic electronics is a branch of electronics and materials science focusing on the development of semiconductors devoted to three main research fields; organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells (OSCs). The contribution of organic electronics to the field of electronics is important as it paves the way toward cheaper, lighter, and more energy efficient devices. In the present context of Photopolymerization, materials that were investigated as photocatalysts were indifferently organic semiconductors used for transistors, charge-transport materials, and light-emitting materials used in electroluminescent devices or conjugated polymers and small molecule dyes for solar cells. In this Account, we summarize our latest developments in elaborating on photocatalytic systems based on these new classes of compounds. Through an in-depth understanding of the parameters governing their reactivities and our efforts to incorporate these materials into photoinitiating systems, we provide new knowledge and a valuable insight for future prospects.
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organic electronics an el dorado in the quest of new photocatalysts for polymerization reactions
Accounts of Chemical Research, 2016Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:ConspectusPhotoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition f...
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Naphthalic anhydride derivatives: structural effects on their initiating abilities in radical and/or cationic Photopolymerizations under visible light
Journal of Polymer Science Part A: Polymer Chemistry, 2015Co-Authors: Pu Xiao, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Bernadette Graff, Jacques LalevéeAbstract:Only one naphthalic anhydride derivative has been reported as light sensitive photoinitiator, this prompted us to further explore the possibility to prepare a new family of photoinitiators based on this scaffold. Therefore, eight naphthalic Naphthalic anhydride derivatives (ANH1-ANH8) have been prepared and combined with an iodonium salt (and optionally N-vinylcarbazole) or an amine (and optionally 2,4,6-tris(trichloromethyl)-1,3,5-triazine) to initiate the cationic polymerization of epoxides and the free radical polymerization of acrylates under different irradiation sources, that is, very soft halogen lamp (∼ 12 mW cm−2), laser diode at 405 nm (∼1.5 mW cm−2) or blue LED centered at 455 nm (80 mW cm−2). The ANH6 based photoinitiating systems are particularly efficient for the cationic and the radical Photopolymerizations, and even better than that of the well-known camphorquinone based systems. The photochemical mechanisms associated with the chemical structure/Photopolymerization efficiency relationships are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin-trapping techniques.
Didier Gigmes - One of the best experts on this subject based on the ideXlab platform.
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Recent Advances and Challenges in the Design of Organic Photoacid and Photobase Generators for Polymerizations
Angewandte Chemie International Edition, 2019Co-Authors: Nicolas Zivic, Frédéric Dumur, Didier Gigmes, Paula K. Kuroishi, Andrew P. Dove, Haritz SardonAbstract:Photopolymerization, or the use of light to trigger polymerization, is one of the most exciting technologies for advanced manufacturing of polymers. One of the key components in the Photopolymerization processes is the photoactive compound that absorbs the light, generating the active species that promotes the polymerization and largely determines the final properties of the material. The field of Photopolymerization has been dominated by photoradical generators to mediate radical reactions. In the last decade, to expand the number of polymers that can be prepared by Photopolymerization, intensive research has been devoted to the synthesis and utilization of photoactive molecules that are able to generate a base or an acid upon irradiation. These organic compounds are known to promote not only the ring-opening polymerization of various heterocyclic monomers such as lactones, carbonates, or epoxides but also to trigger the step-growth synthesis of polyurethanes. This Minireview highlights the recent advances in the development of organic photobase and photoacid generators, with the aim of encouraging the wider application of these photoactive compounds in the Photopolymerization area and to expand the use of these polymers in advanced manufacturing processes.
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Photopolymerization processes of thick films and in shadow areas: a review for the access to composites
Polymer Chemistry, 2017Co-Authors: Patxi Garra, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Celine Dietlin, Jacques LalevéeAbstract:The Photopolymerization processes are currently associated with thin samples for which the light penetration is good enough to activate the photoinitiator or the photoinitiating system for the entre sample's thickness. The Photopolymerization of very thick films and in shadow areas where the light penetration is inhibited (e.g. in filled, pigmented, and dispersed samples) remains a huge challenge (e.g. for the access to composites). In the present paper, an overview of the different strategies for the Photopolymerization of thick samples is reported. First, strategies based on the optimization of the photonic (light intensity, excitation wavelength, etc.) or chemical (efficiency/reactivity/bleaching of the photoinitiating systems, etc.) parameters are presented that result in a full temporal and spatial control. Then, the main strategies based on propagation/diffusion mechanisms of latent species for the curing beyond the irradiated areas are given (partial loss of spatial resolution and access to shadow areas). Also, dual systems (thermal/ photochemical or photochemical/redox) are described. The state of the art for the access to thick samples by Photopolymerization processes as well as some perspectives are provided.
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Organic Electronics: an El Dorado in the quest of new photoCatalysts as photoinitiators of polymerization
Accounts of Chemical Research, 2017Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:Photoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition for light absorption between the chromophores and other species in the formulation are key parameters drastically affecting the Photopolymerization process. To address these issues, photoinitiating systems operating under low intensity visible light irradiation, in the absence of solvents are highly sought after. In this context, the use of photoredox catalysis can be highly advantageous; that is, photoredox catalysts can provide high reactivities with low catalyst loading, permitting access to high performance photoinitiating systems. However, to act as efficient photoredox catalysts, specific criteria have to be fulfilled. A strong absorption over the visible range, an ability to easily oxidize or reduce as well as sufficient photochemical stability are basic prerequisites to make these molecules desirable candidates for photoredox catalysis. Considering the similarity of requirements between organic electronics and Photopolymerization, numerous materials initially designed for applications in organic electronics have been revisited in the context of Photopolymerization. Organic electronics is a branch of electronics and materials science focusing on the development of semiconductors devoted to three main research fields; organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells (OSCs). The contribution of organic electronics to the field of electronics is important as it paves the way toward cheaper, lighter, and more energy efficient devices. In the present context of Photopolymerization, materials that were investigated as photocatalysts were indifferently organic semiconductors used for transistors, charge-transport materials, and light-emitting materials used in electroluminescent devices or conjugated polymers and small molecule dyes for solar cells. In this Account, we summarize our latest developments in elaborating on photocatalytic systems based on these new classes of compounds. Through an in-depth understanding of the parameters governing their reactivities and our efforts to incorporate these materials into photoinitiating systems, we provide new knowledge and a valuable insight for future prospects.
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organic electronics an el dorado in the quest of new photocatalysts for polymerization reactions
Accounts of Chemical Research, 2016Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:ConspectusPhotoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition f...
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Naphthalic anhydride derivatives: structural effects on their initiating abilities in radical and/or cationic Photopolymerizations under visible light
Journal of Polymer Science Part A: Polymer Chemistry, 2015Co-Authors: Pu Xiao, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Bernadette Graff, Jacques LalevéeAbstract:Only one naphthalic anhydride derivative has been reported as light sensitive photoinitiator, this prompted us to further explore the possibility to prepare a new family of photoinitiators based on this scaffold. Therefore, eight naphthalic Naphthalic anhydride derivatives (ANH1-ANH8) have been prepared and combined with an iodonium salt (and optionally N-vinylcarbazole) or an amine (and optionally 2,4,6-tris(trichloromethyl)-1,3,5-triazine) to initiate the cationic polymerization of epoxides and the free radical polymerization of acrylates under different irradiation sources, that is, very soft halogen lamp (∼ 12 mW cm−2), laser diode at 405 nm (∼1.5 mW cm−2) or blue LED centered at 455 nm (80 mW cm−2). The ANH6 based photoinitiating systems are particularly efficient for the cationic and the radical Photopolymerizations, and even better than that of the well-known camphorquinone based systems. The photochemical mechanisms associated with the chemical structure/Photopolymerization efficiency relationships are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin-trapping techniques.
Christopher N Bowman - One of the best experts on this subject based on the ideXlab platform.
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additive manufacture of lightly crosslinked semicrystalline thiol enes for enhanced mechanical performance
Polymer Chemistry, 2020Co-Authors: Kimberly K Childress, Marvin D Alim, Juan J Hernandez, Jeffrey W Stansbury, Christopher N BowmanAbstract:Photopolymerizable semicrystalline thermoplastics resulting from thiol-ene polymerizations were formed via fast polymerizations and achieved excellent mechanical properties. These materials have been shown to produce materials desirable for additive manufacturing (3D printing), especially for recyclable printing and investment casting. However, while well-resolved prints were previously achieved with the thiol-ene thermoplastics, the remarkable elongation at break (ϵmax) and toughness (T) attained in bulk were not realized for 3D printed components (ϵmax,bulk ~ 790%, Tbulk ~ 102 MJ m-3 vs. ϵmax,print < 5%, Tprint < 0.5 MJ m-3). In this work, small concentrations (5-10 mol%) of a crosslinker were added to the original thiol-ene resin composition without sacrificing crystallization potential to achieve semicrystalline, covalently crosslinked networks with enhanced mechanical properties. Improvements in ductility and overall toughness were observed for printed crosslinked structures, and substantial mechanical augmentation was further demonstrated with post-manufacture thermal conditioning of printed materials above the melting temperature (Tm). In some instances, this thermal conditioning to reset the crystalline component of the crosslinked prints yielded mechanical properties that were comparable or superior to its bulk counterpart (ϵmax ~ 790%, T ~ 95 MJ m-3). These unique Photopolymerizations and their corresponding monomer compositions exhibited concurrent polymerization and crystallization along with mechanical properties that were tunable by changes to the monomer composition, Photopolymerization conditions, and post-polymerization conditioning. This is the first example of a 3D printed semicrystalline, crosslinked material with thermally tunable mechanical properties that are superior to many commercially-available resins.
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Photopolymerization reactions using the photoinitiated copper i catalyzed azide alkyne cycloaddition cuaac reaction
Advanced Materials, 2013Co-Authors: Tao Gong, Brian J Adzima, Noah H Baker, Christopher N BowmanAbstract:The first bulk Photopolymerization of multifunctional alkyne and azide monomers using the CuAAC reaction is successfully carried out from low molecular weight, nonviscous monomer resins. Compared to other traditional step-growth bulk Photopolymerization, this approach readily provides crosslinked, high glass transition temperature polymers that incorporate triazole linkages throughout the polymer structure with great temporal control.
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Oxygen inhibition in thiol–acrylate Photopolymerizations
Journal of Polymer Science Part A, 2006Co-Authors: Allison K. O'brien, Neil B. Cramer, Christopher N BowmanAbstract:The overall effects of oxygen on thiol–acrylate Photopolymerizations were characterized. Specially, the choice of thiol monomer chemistry, functionality, and concentration on the extent of oxygen inhibition were considered. As thiol concentration was increased, the degree of oxygen inhibition was greatly reduced because of chain transfer from the peroxy radical to the thiol. When comparing the copolymerization of 1,6-hexanediol diacrylate with the alkane-based thiol (1,6-hexane dithiol) to the copolymerization with the propionate thiol (glycol dimercaptopropionate), it was found that the propionate system was much more reactive and polymerized to a greater extent in the presence of oxygen. In addition, the functionality was considered where the glycol dimercaptopropionate was compared to a tetrafunctional propionate of similar chemistry (pentaerythritol tetrakis(mercaptopropionate)). Given the same thiol concentration, the higher functionality thiol imparted a faster polymerization rate, due to the increased polymer system viscosity, which limited oxygen diffusion and decreased the extent of overall oxygen inhibition. Thus, preliminary insight is provided into how thiol monomer choice affects the extent of oxygen inhibition in thiol–acrylate Photopolymerization. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2007–2014, 2006
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development of a comprehensive free radical Photopolymerization model incorporating heat and mass transfer effects in thick films
Chemical Engineering Science, 2002Co-Authors: Michael D Goodner, Christopher N BowmanAbstract:A comprehensive kinetic model describing Photopolymerization is developed which allows variation of temperature, species concentrations, and light intensity through the thickness of a photopolymerized film. Heat and mass transfer effects are included, as is the generation of heat by both reaction and light absorption. In addition to initiation, propagation, and termination mechanisms, both primary radical termination and inhibition are incorporated into the model. The possible presence and diffusion of an inert solvent are also accounted for. Thus, the model is useful for examining complex polymerization kinetics and behavior in industrially and commercially important thick film Photopolymerizations, such as the curing of contact lenses, dental restorative materials, photolithographic resists, and optoelectronic coatings. The comprehensive model is used to predict polymerization rate, temperature, and conversion profiles in a variety of systems. The effects of heat generation and the thermal boundary conditions are explored, with the result that heat generation in thick samples leads to greatly increased conversions approaching 100 percent. Increased temperature in these samples also may lead to the appearance of two rate maxima, with the first due to the temperature increase and the second caused by the autoacceleration process. The magnitude of the temperature increase, along with the resultant effects, is more pronounced in insulated systems.
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Photochemistry of polymers: Photopolymerization fundamentals and applications
Polymers in Optics: Physics Chemistry and Applications: A Critical Review, 1996Co-Authors: Anandkumar R. Kannurpatti, Robert William Peiffer, C. Allan Guymon, Christopher N BowmanAbstract:The interaction of polymers and light as well as the production of polymers from photoinduced reactions is a vast subject area with numerous varied aspects. These areas include polymer formation from Photopolymerizations, photocrosslinking reactions, and photodegradation reactions. This article will be restricted to reviewing the fundamental aspects of Photopolymerizations as well as a summary of the current applications of Photopolymerizations and other photochemical reactions in polymers.
Jean-pierre Fouassier - One of the best experts on this subject based on the ideXlab platform.
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Photopolymerization processes of thick films and in shadow areas: a review for the access to composites
Polymer Chemistry, 2017Co-Authors: Patxi Garra, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Celine Dietlin, Jacques LalevéeAbstract:The Photopolymerization processes are currently associated with thin samples for which the light penetration is good enough to activate the photoinitiator or the photoinitiating system for the entre sample's thickness. The Photopolymerization of very thick films and in shadow areas where the light penetration is inhibited (e.g. in filled, pigmented, and dispersed samples) remains a huge challenge (e.g. for the access to composites). In the present paper, an overview of the different strategies for the Photopolymerization of thick samples is reported. First, strategies based on the optimization of the photonic (light intensity, excitation wavelength, etc.) or chemical (efficiency/reactivity/bleaching of the photoinitiating systems, etc.) parameters are presented that result in a full temporal and spatial control. Then, the main strategies based on propagation/diffusion mechanisms of latent species for the curing beyond the irradiated areas are given (partial loss of spatial resolution and access to shadow areas). Also, dual systems (thermal/ photochemical or photochemical/redox) are described. The state of the art for the access to thick samples by Photopolymerization processes as well as some perspectives are provided.
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Organic Electronics: an El Dorado in the quest of new photoCatalysts as photoinitiators of polymerization
Accounts of Chemical Research, 2017Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:Photoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition for light absorption between the chromophores and other species in the formulation are key parameters drastically affecting the Photopolymerization process. To address these issues, photoinitiating systems operating under low intensity visible light irradiation, in the absence of solvents are highly sought after. In this context, the use of photoredox catalysis can be highly advantageous; that is, photoredox catalysts can provide high reactivities with low catalyst loading, permitting access to high performance photoinitiating systems. However, to act as efficient photoredox catalysts, specific criteria have to be fulfilled. A strong absorption over the visible range, an ability to easily oxidize or reduce as well as sufficient photochemical stability are basic prerequisites to make these molecules desirable candidates for photoredox catalysis. Considering the similarity of requirements between organic electronics and Photopolymerization, numerous materials initially designed for applications in organic electronics have been revisited in the context of Photopolymerization. Organic electronics is a branch of electronics and materials science focusing on the development of semiconductors devoted to three main research fields; organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells (OSCs). The contribution of organic electronics to the field of electronics is important as it paves the way toward cheaper, lighter, and more energy efficient devices. In the present context of Photopolymerization, materials that were investigated as photocatalysts were indifferently organic semiconductors used for transistors, charge-transport materials, and light-emitting materials used in electroluminescent devices or conjugated polymers and small molecule dyes for solar cells. In this Account, we summarize our latest developments in elaborating on photocatalytic systems based on these new classes of compounds. Through an in-depth understanding of the parameters governing their reactivities and our efforts to incorporate these materials into photoinitiating systems, we provide new knowledge and a valuable insight for future prospects.
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organic electronics an el dorado in the quest of new photocatalysts for polymerization reactions
Accounts of Chemical Research, 2016Co-Authors: Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jacques LalevéeAbstract:ConspectusPhotoinitiated polymerization has been the subject of continued research efforts due to the numerous applications in which this polymerization technique is involved (coatings, inks, adhesives, optoelectronic, laser imaging, stereolithography, nanotechnology, etc.). More recently, Photopolymerization has received renewed interest due to the emergence of 3D-printing technologies. However, despite current academic and industrial interest in Photopolymerization methodologies, a major limitation lies in the slow rates of Photopolymerization. The development of new photoinitiating systems aimed at addressing this limitation is an active area of research. Photopolymerization occurs through the exposure of a curable formulation to light, generating radical and/or cationic species to initiate polymerization. At present, Photopolymerization is facing numerous challenges related to safety, economic and ecological concerns. Furthermore, practical considerations such as the curing depth and the competition f...
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Naphthalic anhydride derivatives: structural effects on their initiating abilities in radical and/or cationic Photopolymerizations under visible light
Journal of Polymer Science Part A: Polymer Chemistry, 2015Co-Authors: Pu Xiao, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Fabrice Morlet-savary, Bernadette Graff, Jacques LalevéeAbstract:Only one naphthalic anhydride derivative has been reported as light sensitive photoinitiator, this prompted us to further explore the possibility to prepare a new family of photoinitiators based on this scaffold. Therefore, eight naphthalic Naphthalic anhydride derivatives (ANH1-ANH8) have been prepared and combined with an iodonium salt (and optionally N-vinylcarbazole) or an amine (and optionally 2,4,6-tris(trichloromethyl)-1,3,5-triazine) to initiate the cationic polymerization of epoxides and the free radical polymerization of acrylates under different irradiation sources, that is, very soft halogen lamp (∼ 12 mW cm−2), laser diode at 405 nm (∼1.5 mW cm−2) or blue LED centered at 455 nm (80 mW cm−2). The ANH6 based photoinitiating systems are particularly efficient for the cationic and the radical Photopolymerizations, and even better than that of the well-known camphorquinone based systems. The photochemical mechanisms associated with the chemical structure/Photopolymerization efficiency relationships are studied by steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin-trapping techniques.
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Visible light sensitive photoinitiating systems: Recent progress in cationic and radical Photopolymerization reactions under soft conditions
Progress in Polymer Science, 2014Co-Authors: Pu Xiao, Frédéric Dumur, Didier Gigmes, Jean-pierre Fouassier, Jing Zhang, Mohamad Ali Tehfe, Fabrice Morlet-savary, Bernadette Graff, Jacques LalevéeAbstract:Although there have been many reports on photoinitiating systems adapted to visible lights for radical Photopolymerization, the challenge for the design and development of photoinitiating systems for cationic Photopolymerization or concomitant radical/cationic Photopolymerization (for interpenetrating polymer network IPN synthesis) with visible lights still remains open. Particularly, the recent development of cheap and easily accessible LEDs operating upon soft visible light irradiations has opened new fields for polymer synthesis. Since 2011, many novel photoinitiating systems based on organic and organometallic compounds with excellent visible light absorption have emerged and exhibited outstanding photoinitiating abilities especially for cationic Photopolymerization. In this review, recent progress (mainly from 2011 to early 2014) in applications of photoinitiators and sensitive photoinitiating systems under visible lights are reported. In addition, their relative efficiencies in the Photopolymerization of different monomers are exemplified and discussed.
