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251.
Dengxia Wang Ahmad Arar Patxi Garra Bernadette Graff Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2020,58(6):811-823
Exploiting highly efficient, environmentally friendly, and economic CTCs (Charger Transfer Complexes) as photo/thermal dual initiators is a huge pursuit of materials practitioners and innovators. To investigate and find out series amines as donors in CTCs, RT-FTIR (Real-Time Fourier Transform Infrared Spectroscopy) was employed to examine the photo initiating efficiency of CTCs based on amines donors and DSC (Differential Scanning Calorimeter) was used to test their thermal initiating ability. The formation of CTCs was investigated and confirmed by molecular orbital (MO) calculations and UV–Vis experimental study. Structure/reactivity/efficiency relationships will be proposed on the base of more than 10 new amine donors. At last, composites based on glass fibers and carbon fibers were fabricated by photo curing and/or photo/thermal dual curing method, which showed excellent mechanical performance in DMA (Dynamic Mechanical Analysis) characterization. This work paves the path toward flexible photo/thermal dual initiators able to react on demand thanks to orthogonal stimuli (light or heat with the same initiating system). It will naturally find use in time and spatially resolved composites manufacturing (were classical simple photoinitiating or thermal systems are inefficient). © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 811–823 相似文献
252.
Azahelicenes as visible light photoinitiators for cationic and radical polymerization: Preparation of photoluminescent polymers and use in high performance LED projector 3D printing resins 下载免费PDF全文
Assi Al Mousawi Frédéric Dumur Patxi Garra Joumana Toufaily Tayssir Hamieh Fabrice Goubard Thanh‐Tuân Bui Bernadette Graff Didier Gigmes Jean Pierre Fouassier Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2017,55(7):1189-1199
In this article, novel azahelicenes (AZs) were synthesized and proposed as high performance visible light photoinitiators for both the free radical polymerization of acrylates and the cationic polymerization (CP) of epoxides upon visible light exposure using Light Emitting Diodes (LEDs) @405, @455, and @470 nm. Excellent polymerization initiating abilities are found and high final conversions were obtained. Remarkably, an exceptional long lifetime photoluminescence property of the polymer films was observed when synthesized in presence of AZs. A full picture of the involved chemical mechanisms is given. AZs being high performance photoinitiators, their use in new cationic LED 3D printing resins will be also presented, that is, the cationic process upon LED projector @405 nm can be useful to reduce the shrinkage usually observed for radical polymerization. LED projector printing is very interesting compared to laser writing as this technology projects the profile of an entire layer of a 3D object at one time. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1189–1199 相似文献
253.
Prof. Pil Seok Chae Prof. Søren G. F. Rasmussen Rohini R. Rana Kamil Gotfryd Andrew C. Kruse Aashish Manglik Kyung Ho Cho Shailika Nurva Prof. Ulrik Gether Prof. Lan Guan Prof. Claus J. Loland Dr. Bernadette Byrne Prof. Brian K. Kobilka Prof. Samuel H. Gellman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(31):9434-9434
254.
Mahmoud Rahal Bernadette Graff Joumana Toufaily Tayssir Hamieh Guillaume Noirbent Didier Gigmes Frdric Dumur Jacques Laleve 《Molecules (Basel, Switzerland)》2021,26(6)
In this paper, nine organic compounds based on the coumarin scaffold and different substituents were synthesized and used as high-performance photoinitiators for free radical photopolymerization (FRP) of meth(acrylate) functions under visible light irradiation using LED at 405 nm. In fact, these compounds showed a very high initiation capacity and very good polymerization profiles (both high rate of polymerization (Rp) and final conversion (FC)) using two and three-component photoinitiating systems based on coum/iodonium salt (0.1%/1% w/w) and coum/iodonium salt/amine (0.1%/1%/1% w/w/w), respectively. To demonstrate the efficiency of the initiation of photopolymerization, several techniques were used to study the photophysical and photochemical properties of coumarins, such as: UV-visible absorption spectroscopy, steady-state photolysis, real-time FTIR, and cyclic voltammetry. On the other hand, these compounds were also tested in direct laser write experiments (3D printing). The synthesis of photocomposites based on glass fiber or carbon fiber using an LED conveyor at 385 nm (0.7 W/cm2) was also examined. 相似文献
255.
Marius Ghergu Georges Griso Houari Mechkour Bernadette Miara 《Comptes Rendus Mecanique》2005,333(3):249-255
In this Note we establish the limit constitutive law of a piezoelectric material with periodically perforated microstructures and whose reference configuration is a thin shell with fixed thickness. The justification of the new associated model (we show that the limit global and local problems are more complicated than the intial one) is obtained using the periodic unfolding method introduced by Cioranescu, Damlamian and Griso. To cite this article: M. Ghergu et al., C. R. Mecanique 333 (2005). 相似文献
256.
Dr. Xuewei Zhang Dr. Andrés F. Cardozo Si Chen Dr. Wenjing Zhang Dr. Carine Julcour Dr. Muriel Lansalot Dr. Jean‐François Blanco Dr. Florence Gayet Prof. Henri Delmas Prof. Bernadette Charleux Dr. Eric Manoury Dr. Franck D'Agosto Prof. Rinaldo Poli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15505-15517
Water‐borne phosphine‐functionalized core‐cross‐linked micelles ( CCM ) consisting of a hydrophobic core and a hydrophilic shell were obtained as stable latexes by reversible addition–fragmentation chain transfer (RAFT) in water in a one‐pot, three‐step process. Initial homogeneous aqueous‐phase copolymerization of methacrylic acid (MAA) and poly(ethylene oxide) methyl ether methacrylate (PEOMA) is followed by copolymerization of styrene (S) and 4‐diphenylphosphinostyrene (DPPS), yielding P(MAA‐co‐PEOMA)‐b‐P(S‐co‐DPPS) amphiphilic block copolymer micelles ( M ) by polymerization‐induced self‐assembly (PISA), and final micellar cross‐linking with a mixture of S and diethylene glycol dimethacrylate. The CCM were characterized by dynamic light scattering and NMR spectroscopy to evaluate size, dispersity, stability, and the swelling ability of various organic substrates. Coordination of [Rh(acac)(CO)2] (acac=acetylacetonate) to the core‐confined phosphine groups was rapid and quantitative. The CCM and M latexes were then used, in combination with [Rh(acac)(CO)2], to catalyze the aqueous biphasic hydroformylation of 1‐octene, in which they showed high activity, recyclability, protection of the activated Rh center by the polymer scaffold, and low Rh leaching. The CCM latex gave slightly lower catalytic activity but significantly less Rh leaching than the M latex. A control experiment conducted in the presence of the sulfoxantphos ligand pointed to the action of the CCM as catalytic nanoreactors with substrate and product transport into and out of the polymer core, rather than as a surfactant in interfacial catalysis. 相似文献
257.
Velocity of a Molecule Evaporated from a Water Nanodroplet: Maxwell–Boltzmann Statistics versus Non‐Ergodic Events 下载免费PDF全文
Assist. Prof. Dr. Hassan Abdoul‐Carime Francis Berthias Dr. Linda Feketeová Dr. Mathieu Marciante Dr. Florent Calvo Dr. Valérian Forquet Prof. Dr. Henry Chermette Dr. Bernadette Farizon Prof. Dr. Michel Farizon Prof. Dr. Tilmann D. Märk 《Angewandte Chemie (International ed. in English)》2015,54(49):14685-14689
The velocity of a molecule evaporated from a mass‐selected protonated water nanodroplet is measured by velocity map imaging in combination with a recently developed mass spectrometry technique. The measured velocity distributions allow probing statistical energy redistribution in ultimately small water nanodroplets after ultrafast electronic excitation. As the droplet size increases, the velocity distribution rapidly approaches the behavior expected for macroscopic droplets. However, a distinct high‐velocity contribution provides evidence of molecular evaporation before complete energy redistribution, corresponding to non‐ergodic events. 相似文献
258.
Xuehua Fan Hongbin Chen Philippe Goloub Xiang'ao Xia Wenxing Zhang Bernadette Chatenet 《中国颗粒学报》2006,4(6):330-335
Aerosol Optical Thickness (AOT), water vapor content and derived Angstrom exponent acquired by a CIMEL sun photometer in Beijing are analyzed. Monthly means computed from quality-assured daily means, seasonal trends and inter-annual variations are presented and discussed. Summer has the highest seasonal average AOT at 440 nm (τa440), Angstrom exponent (α440-870) and water vapor content with the values 0.93, 1.34 and 3.0 cm, respectively. The second highest seasonal average τa440 appears in spring with the largest variation of α440-870 and minimum α440-870 0.99 due to the impact of coarse particles. The minimum seasonal average τa440 (0.44) and water vapor content (0.4 cm) appear in winter. The annual average τa440 , α440-870 and water vapor content for about 4-year observation period are 0.70, 1.19 and 1.4 cm, respectively. All monthly average Angstrom exponents are within 0.8-1.4. which indicates aerosol in Beijing is a very complex mixture of both fine- and coarse-mode particles (from anthropogenic influence and natural mineral dust). 相似文献
259.
Bernadette Miara 《Archive for Rational Mechanics and Analysis》1998,142(4):331-353
We consider a family of three‐dimensional shells with the same middle surface, all composed of the same nonlinearly elastic
Saint Venant‐Kirchhoff material. Using the method of asymptotic expansions with the thickness as the “small” parameter, and
making specific assumptions on the applied forces, the geometry of the middle surface, and the kinematic boundary conditions,
we show how a “limiting”, “large‐deformation” two‐dimensional model can be identified in this fashion. By linearization, this
nonlinear membrane model reduces to the linear membrane model.
(Accepted January 13, 1997) 相似文献
260.
Influence of Electronic Effects on the Reactivity of Triazolylidene‐Boryl Radicals: Consequences for the use of N‐Heterocyclic Carbene Boranes in Organic and Polymer Synthesis 下载免费PDF全文
Sofia Telitel Anne‐Laure Vallet Darrin M. Flanigan Dr. Bernadette Graff Dr. Fabrice Morlet‐Savary Prof. Tomislav Rovis Prof. Jacques Lalevée Dr. Emmanuel Lacôte 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13772-13777
A small library of triazolylidene‐boranes that differ only in the nature of the aryl group on the external nitrogen atom was prepared. Their reactivity as hydrogen‐atom donors, as well as that of the corresponding N‐heterocyclic carbene (NHC)‐boryl radicals toward methyl acrylate and oxygen, was investigated by laser flash photolysis, molecular orbital calculations, and ESR spin‐trapping experiments, and benchmarked relative to the already known dimethyltriazolylidene‐borane. The new NHC‐boranes were also used as co‐initiators for the Type I photopolymerization of acrylates. This allowed a structure–reactivity relationship with regard to the substitution pattern of the NHC to be established and the role of electronic effects in the reactivity of NHC‐boryl radicals to be probed. Although their rate of addition to methyl acrylate depends on their electronegativity, the radicals are all nucleophilic and good initiators for photopolymerization reactions. 相似文献