X Allonas - Academia.edu (original) (raw)

Papers by X Allonas

Research paper thumbnail of Application of High Performance Photoinitiating Systems for Holographic Grating Recording

Holographic Materials and Optical Systems, 2017

Research paper thumbnail of Quaternary ammonium salts of phenylglyolyxic acid as photobase generators for thiol-promoted epoxides photopolymerization

Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.

Research paper thumbnail of New Visible-Light Photoinitiating Systems for Free-Radical and Cationic Photopolymerization

In this paper, visible light photoinitiating systems are developed for Free Radical Photopolymeri... more In this paper, visible light photoinitiating systems are developed for Free Radical Photopolymerization FRP and Free Radical Promoted Cationic Photopolymerization FRPCP. In the former case, the use of a pyrromethene dye was found to yield high rate of polymerization as well as high final conversion when combined with an amine and a redox additive such as a triazine. The mechanism of reaction was investigated by laser flash photolysis, providing useful information to determine the mechanism of reaction. In the case of FRPCP, the outstanding properties of silyl radicals as reactant for the decomposition of iodonium salt are described. It is shown that efficient FRPCP can be carried out under visible light using camphorquinone as light absorbing species.

Research paper thumbnail of Effect of the oxygen affected layer in multilayered photopolymers

Polymer Chemistry, 2017

Photopolymerization is known to be limited in depth by light absorption.

Research paper thumbnail of Isomerization controlled photopolymerization: effect of dye photophysics on photoinitiation efficiency

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Aug 4, 2016

The efficiency of free radical polymerization by photoinitiating systems based on two Astrazon or... more The efficiency of free radical polymerization by photoinitiating systems based on two Astrazon orange cyanine dyes was shown to be directly related to the isomerization process of the dye in the excited states. The impact of resin viscosity on photopolymerization reactions was measured and related to the overall radical quantum yields. The quantum yields were calculated according to the photocyclic behaviour of the initiating systems based on the Astrazon orange dyes. These dyes are characterized by a viscosity dependent photophysics, which leads to an isomerization-diffusion-controlled photopolymerization. Besides this demonstration, Astrazon orange dyes appeared to be very good candidates for free radical photopolymerization in the visible, presenting high absorption coefficient, low cost and good sensitivity.

Research paper thumbnail of Computational study of ground and triplet states of acetophenone oxime derivatives

Journal of Molecular Structure: THEOCHEM, 2002

Abstract The main structural changes occurring during the sensitized S 0 –T 1 transition of aceto... more Abstract The main structural changes occurring during the sensitized S 0 –T 1 transition of acetophenone oxime derivatives were investigated at HF/6-31+G(d) and B3LYP/6-31+G(d) levels. The geometry of the S 0 and T 1 states was calculated and the evolution of the dihedral angle CCNO as a function of the oxime structure was correlated with the red shift of the ground state absorption. The triplet energy levels of these compounds were determined by use of B3LYP hybrid functional, and confirm the experimental finding that the triplet energy level do not depend on the constrain imposed on the acetophenone oxime structure. A good agreement between experimental and calculated values was found with a difference of about 7 kcal/mol. Moreover, triplet states of these compounds were shown to exhibit an important biradical character. The whole results confirm the CN twist occurring in the triplet state and put forward the crucial role of C–C–N–O bond torsion involved in the stabilization of this excited state.

Research paper thumbnail of Sensitization of Thianthrenium Salt for Cationic Polymerization of Epoxides

Journal of Photopolymer Science and Technology, 2010

Research paper thumbnail of New Opportunities in Free Radical Photopolymerization and Free Radical Promoted Cationic Polymerization Based on the Silyl Radical Chemistry

Journal of Photopolymer Science and Technology, 2009

Research paper thumbnail of Evaluation of the Exothermicity of Free Radical Photopolymerization through a RT-FTIR and PhotoDSC Study

Journal of Photopolymer Science and Technology, 2010

Research paper thumbnail of How transient photoconductivity reveals significant features of the reduction of ground-state aromatic ketones by amino-alkyl radicals through a thermal electron-transfer process

Research on Chemical Intermediates, 2003

The rate constants k red of the thermal electron-transfer reaction between several aminoalkyl rad... more The rate constants k red of the thermal electron-transfer reaction between several aminoalkyl radicals and two ground-state aromatic ketones, benzophenone (BP) and thioxanthone (TX), were measured by nanosecond transient photoconductivity in acetonitrile. The k red values were strongly at variance from those expected from the free energy change 1G red of the reaction within the framework of the Marcus' theory of electron transfer. Moreover, addition of small amounts of water in acetonitrile strongly enhanced k red and the ion quantum yield. These results were rationalized by invoking a 1 : 1 complex formation between amino-alkyl radicals and water, and semi-empirical AM1 calculations were used to sustain this explanation.

Research paper thumbnail of Photoassisted oxypolymerization of alkyd resins: Kinetics and mechanisms

Progress in Organic Coatings, 2012

ABSTRACT A new three-component system for photoassisted oxypolymerization of alkyd resins contain... more ABSTRACT A new three-component system for photoassisted oxypolymerization of alkyd resins containing a drier, a photosensitizer and a radical generator was investigated. Polymerization profiles were recorded by real-time infrared spectroscopy for a thin film exposed for 1 h to simulated sunlight radiation. The kinetic results showed that the system follows complex kinetics. Multiple regression analysis was used to model the influence of the drier, the photosensitizer and the radical generator on the final conversion and total polymerization rate during photooxidation. The mechanisms involved were studied through laser spectroscopies. Laser flash photolysis was used to measure the rate constants of reaction between the radicals formed from the photodissociation of the radical generator and the model compounds of alkyd resins, leading to the rapid formation of hydroperoxides. The photosensitizer was expected to produce singlet state molecular oxygen that reacts on the alkyd resin, and time-resolved chemiluminescence technique was used to determine the quenching rate constant of singlet oxygen by model compounds. On the basis of these results, a mechanism for the photoassisted oxypolymerization of alkyd resins is proposed that account for the all the different reaction pathways.

Research paper thumbnail of Camphorquinone–amines photoinitating systems for the initiation of free radical polymerization

Polymer, 2003

Results of the camphorquinone/hindered piperidines, visible-light photoinduced polymerization of ... more Results of the camphorquinone/hindered piperidines, visible-light photoinduced polymerization of triethyleneglycol dimethacrylate are presented. The effectiveness of piperidines as a coinitiator is compared with a few aliphatic amines and aromatic amines. The main objective in this research was to study the mechanism of photoinitiation of polymerization. Reactive radicals that initiate the polymerization are formed by a mechanism of hydrogen atom abstraction by the triplet state of camphorquinone, mediated by photoinduced electron transfer. The different efficiencies of the aliphatic amines and of the aromatic amines affecting photopolymerization are explained on the basis of the different quenching reactivities of the excited states of camphorquinone.

Research paper thumbnail of Optimization of a photopolymerizable material based on a photocyclic initiating system using holographic recording

Photochemical & Photobiological Sciences, 2012

A set of photoinitiating systems (PIS) for free radical photopolymerization was studied using tim... more A set of photoinitiating systems (PIS) for free radical photopolymerization was studied using time-resolved spectroscopic experiments, real-time FTIR and holographic recording. It is shown that the efficiency of the photoinitiating system can be drastically increased when a redox additive is added to the conventional dye/coinitiator system by virtue of photocyclic behaviour. The homogeneous photopolymerization process was found to reach a fast vitrification, limiting the conversion at about 55%. By contrast, holographic recording underlines the differences in photoinitiating system reactivity, allowing diffraction efficiencies close to unity for the most reactive PIS. † This article is published as part of a themed issue in honour of Jean-Pierre Desvergne on the occasion of his 65th birthday.

Research paper thumbnail of Excited state processes in a four-component photosensitive system based on a bisimidazole derivative

Photochemical & Photobiological Sciences, 2003

The four component system consisting of bis[2-(o-chlorophenyl)-4,5-diphenylimidazole] (Cl-HABI), ... more The four component system consisting of bis[2-(o-chlorophenyl)-4,5-diphenylimidazole] (Cl-HABI), N,NЈ-bis(diethylamino)benzophenone (EAB), N-phenylglycine (NPG) and an iodonium salt (BIP-T) can be used for the photoinitiation of radical polymerization reactions. The excited state processes involved are reported and all the transient species, including the triplet state and ketyl radical of EAB as well as the lophyl radical, are characterized. Rate constants of interaction between the different partners in the four component system are determined. Redox potentials of the different compounds are evaluated enabling the free energies for electron transfer reactions to be calculated. An overall scheme for the evolution of the excited states and a general discussion on the role played by the different components in photoinitiating polymerization are then provided.

Research paper thumbnail of New Photoiniferters: Respective Role of the Initiating and Persistent Radicals

Research paper thumbnail of New Photoinitiators Based on the Silyl Radical Chemistry: Polymerization Ability, ESR Spin Trapping, and Laser Flash Photolysis Investigation

Macromolecules, 2008

... J. Lalev e*, N. Blanchard, M. El-Roz, B. Graff, X. Allonas, JP Fouassier. Department of Photo... more ... J. Lalev e*, N. Blanchard, M. El-Roz, B. Graff, X. Allonas, JP Fouassier. Department of Photochemistry, UMR 7525 CNRS, University of Haute Alsace, ENSCMu, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France, and Department ...

Research paper thumbnail of New Highly Efficient Radical Photoinitiators Based on Si−Si Bond Cleavage

Macromolecules, 2007

... N-Heterocyclic Carbenes−Borane Complexes: A New Class of Initiators for Radical Photopolymeri... more ... N-Heterocyclic Carbenes−Borane Complexes: A New Class of Initiators for Radical Photopolymerization. Mohamad-Ali Tehfe, Malika Makhlouf Brahmi, Jean-Pierre Fouassier, Dennis P. Curran, Max Malacria, Louis Fensterbank, Emmanuel Lac te and Jacques Lalev e. ...

Research paper thumbnail of Direct measurements of the addition and recombination of acrylate radicals: Access to propagation and termination rate constants?

Journal of Polymer Science Part A: Polymer Chemistry, 2006

Acrylate radicals produced by the addition of an aminoalkyl radical to five acrylate monomers wer... more Acrylate radicals produced by the addition of an aminoalkyl radical to five acrylate monomers were directly observed by transient absorption spectroscopy, which allowed us to easily follow their chemical reactivity. It was possible (1) to characterize their absorption in the visible part of the spectrum, (2) to calculate their absorption properties, (3) to determine the energy barriers of the addition through quantum mechanical calculations, (4) to monitor the kinetics of the subsequent addition to another monomer unit, and (5) to follow the recombination of two acrylate radicals. These two latter points could mimic the propagation and termination reactions of polymerization-propagating acrylate radicals. Methacrylate and acrylonitrile radicals were also studied. The obtained results were in good agreement with the propagation rate constants determined by the well-established pulsed laser polymerization techniques. Our method could likely provide rapid access to both the propagation and termination rate constants in suitable systems and appears to be powerful and promising for studying and comparing the reactivities of different acrylate monomer structures.

Research paper thumbnail of Controlled photopolymerization reactions: The reactivity of new photoiniferters

Journal of Polymer Science Part A: Polymer Chemistry, 2007

Four new structures (o,o-diethyl dithiobisthioformate, isopropylxanthic disulfide, tetramethyldic... more Four new structures (o,o-diethyl dithiobisthioformate, isopropylxanthic disulfide, tetramethyldicarbonotrithioic diamide, and phenylacetyl disulfide) are proposed as photoiniferters for controlled photopolymerization reactions. Their photochemical properties, efficiency in controlling the photopolymerization of methyl methacrylate (MMA), and ability to photocrosslink a difunctional acrylate monomer [1,6-hexane diol diacrylate (HDDA)] are investigated. The rates of polymerization of MMA and HDDA and the number-average molecular weights (Mn's) and polydispersity indices (PDIs) of poly(methyl methacrylate) have been determined. The transient absorption spectra and interaction rate constants of the radicals have been measured. Both the (alkyloxythiocarbonyl)thiyl and (benzylcarbonyl)thiyl radicals are efficient in controlling a photopolymerization process. For a 40% monomer conversion obtained in a few minutes, the Mn values range from 6000 to 14,000, and the PDIs can reach 1.6–2.2. A fivefold reduction of the light intensity increases Mn by 25% and reduces PDI by 5%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2436–2442, 2007

Research paper thumbnail of Effect of Lewis base coordination on boryl radical reactivity: investigation using laser flash photolysis and kinetic ESR

Journal of Physical Organic Chemistry, 2009

... Jacques Lalevée 1,* ,; Nicolas Blanchard 2 ,; Anne-Caroline Chany 2 ,; Mohamad-Ali Tehfe 1 ,;... more ... Jacques Lalevée 1,* ,; Nicolas Blanchard 2 ,; Anne-Caroline Chany 2 ,; Mohamad-Ali Tehfe 1 ,; Xavier Allonas 1 ,; Jean-Pierre Fouassier 1. Article first published online: 21 APR 2009. ... Lalevée, A. Dirani, M. El-Roz, X. Allonas, JP Fouassier, Macromolecules 2008, 41, 2003–2010. ...

Research paper thumbnail of Application of High Performance Photoinitiating Systems for Holographic Grating Recording

Holographic Materials and Optical Systems, 2017

Research paper thumbnail of Quaternary ammonium salts of phenylglyolyxic acid as photobase generators for thiol-promoted epoxides photopolymerization

Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.

Research paper thumbnail of New Visible-Light Photoinitiating Systems for Free-Radical and Cationic Photopolymerization

In this paper, visible light photoinitiating systems are developed for Free Radical Photopolymeri... more In this paper, visible light photoinitiating systems are developed for Free Radical Photopolymerization FRP and Free Radical Promoted Cationic Photopolymerization FRPCP. In the former case, the use of a pyrromethene dye was found to yield high rate of polymerization as well as high final conversion when combined with an amine and a redox additive such as a triazine. The mechanism of reaction was investigated by laser flash photolysis, providing useful information to determine the mechanism of reaction. In the case of FRPCP, the outstanding properties of silyl radicals as reactant for the decomposition of iodonium salt are described. It is shown that efficient FRPCP can be carried out under visible light using camphorquinone as light absorbing species.

Research paper thumbnail of Effect of the oxygen affected layer in multilayered photopolymers

Polymer Chemistry, 2017

Photopolymerization is known to be limited in depth by light absorption.

Research paper thumbnail of Isomerization controlled photopolymerization: effect of dye photophysics on photoinitiation efficiency

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Aug 4, 2016

The efficiency of free radical polymerization by photoinitiating systems based on two Astrazon or... more The efficiency of free radical polymerization by photoinitiating systems based on two Astrazon orange cyanine dyes was shown to be directly related to the isomerization process of the dye in the excited states. The impact of resin viscosity on photopolymerization reactions was measured and related to the overall radical quantum yields. The quantum yields were calculated according to the photocyclic behaviour of the initiating systems based on the Astrazon orange dyes. These dyes are characterized by a viscosity dependent photophysics, which leads to an isomerization-diffusion-controlled photopolymerization. Besides this demonstration, Astrazon orange dyes appeared to be very good candidates for free radical photopolymerization in the visible, presenting high absorption coefficient, low cost and good sensitivity.

Research paper thumbnail of Computational study of ground and triplet states of acetophenone oxime derivatives

Journal of Molecular Structure: THEOCHEM, 2002

Abstract The main structural changes occurring during the sensitized S 0 –T 1 transition of aceto... more Abstract The main structural changes occurring during the sensitized S 0 –T 1 transition of acetophenone oxime derivatives were investigated at HF/6-31+G(d) and B3LYP/6-31+G(d) levels. The geometry of the S 0 and T 1 states was calculated and the evolution of the dihedral angle CCNO as a function of the oxime structure was correlated with the red shift of the ground state absorption. The triplet energy levels of these compounds were determined by use of B3LYP hybrid functional, and confirm the experimental finding that the triplet energy level do not depend on the constrain imposed on the acetophenone oxime structure. A good agreement between experimental and calculated values was found with a difference of about 7 kcal/mol. Moreover, triplet states of these compounds were shown to exhibit an important biradical character. The whole results confirm the CN twist occurring in the triplet state and put forward the crucial role of C–C–N–O bond torsion involved in the stabilization of this excited state.

Research paper thumbnail of Sensitization of Thianthrenium Salt for Cationic Polymerization of Epoxides

Journal of Photopolymer Science and Technology, 2010

Research paper thumbnail of New Opportunities in Free Radical Photopolymerization and Free Radical Promoted Cationic Polymerization Based on the Silyl Radical Chemistry

Journal of Photopolymer Science and Technology, 2009

Research paper thumbnail of Evaluation of the Exothermicity of Free Radical Photopolymerization through a RT-FTIR and PhotoDSC Study

Journal of Photopolymer Science and Technology, 2010

Research paper thumbnail of How transient photoconductivity reveals significant features of the reduction of ground-state aromatic ketones by amino-alkyl radicals through a thermal electron-transfer process

Research on Chemical Intermediates, 2003

The rate constants k red of the thermal electron-transfer reaction between several aminoalkyl rad... more The rate constants k red of the thermal electron-transfer reaction between several aminoalkyl radicals and two ground-state aromatic ketones, benzophenone (BP) and thioxanthone (TX), were measured by nanosecond transient photoconductivity in acetonitrile. The k red values were strongly at variance from those expected from the free energy change 1G red of the reaction within the framework of the Marcus' theory of electron transfer. Moreover, addition of small amounts of water in acetonitrile strongly enhanced k red and the ion quantum yield. These results were rationalized by invoking a 1 : 1 complex formation between amino-alkyl radicals and water, and semi-empirical AM1 calculations were used to sustain this explanation.

Research paper thumbnail of Photoassisted oxypolymerization of alkyd resins: Kinetics and mechanisms

Progress in Organic Coatings, 2012

ABSTRACT A new three-component system for photoassisted oxypolymerization of alkyd resins contain... more ABSTRACT A new three-component system for photoassisted oxypolymerization of alkyd resins containing a drier, a photosensitizer and a radical generator was investigated. Polymerization profiles were recorded by real-time infrared spectroscopy for a thin film exposed for 1 h to simulated sunlight radiation. The kinetic results showed that the system follows complex kinetics. Multiple regression analysis was used to model the influence of the drier, the photosensitizer and the radical generator on the final conversion and total polymerization rate during photooxidation. The mechanisms involved were studied through laser spectroscopies. Laser flash photolysis was used to measure the rate constants of reaction between the radicals formed from the photodissociation of the radical generator and the model compounds of alkyd resins, leading to the rapid formation of hydroperoxides. The photosensitizer was expected to produce singlet state molecular oxygen that reacts on the alkyd resin, and time-resolved chemiluminescence technique was used to determine the quenching rate constant of singlet oxygen by model compounds. On the basis of these results, a mechanism for the photoassisted oxypolymerization of alkyd resins is proposed that account for the all the different reaction pathways.

Research paper thumbnail of Camphorquinone–amines photoinitating systems for the initiation of free radical polymerization

Polymer, 2003

Results of the camphorquinone/hindered piperidines, visible-light photoinduced polymerization of ... more Results of the camphorquinone/hindered piperidines, visible-light photoinduced polymerization of triethyleneglycol dimethacrylate are presented. The effectiveness of piperidines as a coinitiator is compared with a few aliphatic amines and aromatic amines. The main objective in this research was to study the mechanism of photoinitiation of polymerization. Reactive radicals that initiate the polymerization are formed by a mechanism of hydrogen atom abstraction by the triplet state of camphorquinone, mediated by photoinduced electron transfer. The different efficiencies of the aliphatic amines and of the aromatic amines affecting photopolymerization are explained on the basis of the different quenching reactivities of the excited states of camphorquinone.

Research paper thumbnail of Optimization of a photopolymerizable material based on a photocyclic initiating system using holographic recording

Photochemical & Photobiological Sciences, 2012

A set of photoinitiating systems (PIS) for free radical photopolymerization was studied using tim... more A set of photoinitiating systems (PIS) for free radical photopolymerization was studied using time-resolved spectroscopic experiments, real-time FTIR and holographic recording. It is shown that the efficiency of the photoinitiating system can be drastically increased when a redox additive is added to the conventional dye/coinitiator system by virtue of photocyclic behaviour. The homogeneous photopolymerization process was found to reach a fast vitrification, limiting the conversion at about 55%. By contrast, holographic recording underlines the differences in photoinitiating system reactivity, allowing diffraction efficiencies close to unity for the most reactive PIS. † This article is published as part of a themed issue in honour of Jean-Pierre Desvergne on the occasion of his 65th birthday.

Research paper thumbnail of Excited state processes in a four-component photosensitive system based on a bisimidazole derivative

Photochemical & Photobiological Sciences, 2003

The four component system consisting of bis[2-(o-chlorophenyl)-4,5-diphenylimidazole] (Cl-HABI), ... more The four component system consisting of bis[2-(o-chlorophenyl)-4,5-diphenylimidazole] (Cl-HABI), N,NЈ-bis(diethylamino)benzophenone (EAB), N-phenylglycine (NPG) and an iodonium salt (BIP-T) can be used for the photoinitiation of radical polymerization reactions. The excited state processes involved are reported and all the transient species, including the triplet state and ketyl radical of EAB as well as the lophyl radical, are characterized. Rate constants of interaction between the different partners in the four component system are determined. Redox potentials of the different compounds are evaluated enabling the free energies for electron transfer reactions to be calculated. An overall scheme for the evolution of the excited states and a general discussion on the role played by the different components in photoinitiating polymerization are then provided.

Research paper thumbnail of New Photoiniferters: Respective Role of the Initiating and Persistent Radicals

Research paper thumbnail of New Photoinitiators Based on the Silyl Radical Chemistry: Polymerization Ability, ESR Spin Trapping, and Laser Flash Photolysis Investigation

Macromolecules, 2008

... J. Lalev e*, N. Blanchard, M. El-Roz, B. Graff, X. Allonas, JP Fouassier. Department of Photo... more ... J. Lalev e*, N. Blanchard, M. El-Roz, B. Graff, X. Allonas, JP Fouassier. Department of Photochemistry, UMR 7525 CNRS, University of Haute Alsace, ENSCMu, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France, and Department ...

Research paper thumbnail of New Highly Efficient Radical Photoinitiators Based on Si−Si Bond Cleavage

Macromolecules, 2007

... N-Heterocyclic Carbenes−Borane Complexes: A New Class of Initiators for Radical Photopolymeri... more ... N-Heterocyclic Carbenes−Borane Complexes: A New Class of Initiators for Radical Photopolymerization. Mohamad-Ali Tehfe, Malika Makhlouf Brahmi, Jean-Pierre Fouassier, Dennis P. Curran, Max Malacria, Louis Fensterbank, Emmanuel Lac te and Jacques Lalev e. ...

Research paper thumbnail of Direct measurements of the addition and recombination of acrylate radicals: Access to propagation and termination rate constants?

Journal of Polymer Science Part A: Polymer Chemistry, 2006

Acrylate radicals produced by the addition of an aminoalkyl radical to five acrylate monomers wer... more Acrylate radicals produced by the addition of an aminoalkyl radical to five acrylate monomers were directly observed by transient absorption spectroscopy, which allowed us to easily follow their chemical reactivity. It was possible (1) to characterize their absorption in the visible part of the spectrum, (2) to calculate their absorption properties, (3) to determine the energy barriers of the addition through quantum mechanical calculations, (4) to monitor the kinetics of the subsequent addition to another monomer unit, and (5) to follow the recombination of two acrylate radicals. These two latter points could mimic the propagation and termination reactions of polymerization-propagating acrylate radicals. Methacrylate and acrylonitrile radicals were also studied. The obtained results were in good agreement with the propagation rate constants determined by the well-established pulsed laser polymerization techniques. Our method could likely provide rapid access to both the propagation and termination rate constants in suitable systems and appears to be powerful and promising for studying and comparing the reactivities of different acrylate monomer structures.

Research paper thumbnail of Controlled photopolymerization reactions: The reactivity of new photoiniferters

Journal of Polymer Science Part A: Polymer Chemistry, 2007

Four new structures (o,o-diethyl dithiobisthioformate, isopropylxanthic disulfide, tetramethyldic... more Four new structures (o,o-diethyl dithiobisthioformate, isopropylxanthic disulfide, tetramethyldicarbonotrithioic diamide, and phenylacetyl disulfide) are proposed as photoiniferters for controlled photopolymerization reactions. Their photochemical properties, efficiency in controlling the photopolymerization of methyl methacrylate (MMA), and ability to photocrosslink a difunctional acrylate monomer [1,6-hexane diol diacrylate (HDDA)] are investigated. The rates of polymerization of MMA and HDDA and the number-average molecular weights (Mn's) and polydispersity indices (PDIs) of poly(methyl methacrylate) have been determined. The transient absorption spectra and interaction rate constants of the radicals have been measured. Both the (alkyloxythiocarbonyl)thiyl and (benzylcarbonyl)thiyl radicals are efficient in controlling a photopolymerization process. For a 40% monomer conversion obtained in a few minutes, the Mn values range from 6000 to 14,000, and the PDIs can reach 1.6–2.2. A fivefold reduction of the light intensity increases Mn by 25% and reduces PDI by 5%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2436–2442, 2007

Research paper thumbnail of Effect of Lewis base coordination on boryl radical reactivity: investigation using laser flash photolysis and kinetic ESR

Journal of Physical Organic Chemistry, 2009

... Jacques Lalevée 1,* ,; Nicolas Blanchard 2 ,; Anne-Caroline Chany 2 ,; Mohamad-Ali Tehfe 1 ,;... more ... Jacques Lalevée 1,* ,; Nicolas Blanchard 2 ,; Anne-Caroline Chany 2 ,; Mohamad-Ali Tehfe 1 ,; Xavier Allonas 1 ,; Jean-Pierre Fouassier 1. Article first published online: 21 APR 2009. ... Lalevée, A. Dirani, M. El-Roz, X. Allonas, JP Fouassier, Macromolecules 2008, 41, 2003–2010. ...