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The emission spectrum of a blue LED centered at 477 nm (SmartLite Focus from Dentsply Sirona Germany).
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Diaryliodonium salts are well-established compounds in free radical chemistry and are already used as photoinitiators (free radical or cationic polymerization), but the presence of counter anions is a strong drawback. Indeed, a counter anion is always required (e.g., SbF6−) leading to potential toxicity issues or release of HF. In the present paper...
Contexts in source publication
Context 1
... blue LED@477nm representative of dental materials usage (SmartLite Focus from Dentsply Sirona ~300 mW.cm −2 in the selected conditions; see emission spectrum in Figure 1) and an LED Scheme 2. Structures of the photoinitiator (camphorquinone; CQ) and additives/co-initiators used. ...
Context 2
... blue LED@477nm representative of dental materials usage (SmartLite Focus from Dentsply Sirona ~300 mW.cm −2 in the selected conditions; see emission spectrum in Figure 1) and an LED Scheme 3. Structures of the monomers used. ...
Context 3
... blue LED@477nm representative of dental materials usage (SmartLite Focus from Dentsply Sirona ~300 mW·cm −2 in the selected conditions; see emission spectrum in Figure 1) and an LED centered at 455 nm (M455L3-ThorLabs; ~80 mW·cm −2 ) were used for the irradiation of the photocurable samples. centered at 455 nm (M455L3-ThorLabs; ~80 mW.cm −2 ) were used for the irradiation of the photocurable samples. ...
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... result clearly highlights the cleavage of the C-I central bond of S5 and the possible release of benzene by the decomposition of S5 (through hydrogen abstraction process with the generated phenyl radical in S5). As benzene release must be clearly avoided in industrial applications for safety reasons, a derivative of S5 was prepared where the phenyl group was replaced by a 2,4,6-trimethylphenyl (mesityl) group: S6. λ (nm) Figure 1. The emission spectrum of a blue LED centered at 477 nm (SmartLite Focus from Dentsply Sirona Germany). ...
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Free radical polymerization is often performed by thermal initiation but also more and more by light-assisted polymerization processes. This second approach allows the polymerization to be carried out under mild conditions (under air, upon blue light exposure, under low light intensity). The aim and the originality of the present paper is to perfor...
Currently, increasing attention has been focused on light-emitting diodes (LEDs)-induced photopolymerization. The common LEDs (e.g., LED at 365 nm and LED at 405 nm) possess narrow emission bands. Due to their light absorption properties, most commercial photoinitiators are sensitive to UV light and cannot be optimally activated under visible LED i...
In a significant breakthrough from classical molecular (i.e., nonpolymeric) iodonium salts in light-induced photochemistry, the synthesis and use of new safer polymeric iodonium salts are reported here. They are shown to be involved in charge transfer complexes (CTCs) while in interaction with a safe amino acid derivative (N-phenylglycine). Also, t...
Photopolymerization offers a unique opportunity to convert liquid monomers to polymers using light as the activation source. Recently, major efforts have been devoted to developing visible light photo-initiating systems, and the search for new dyes that can be incorporated into photocurable resins and polymerize a resin within a few seconds is stil...
Citations
... Light sources (lasers, LED or lamps) having light spectra ranging from UV (365 nm), visible (430 nm to 660 nm) to near infrared (750 nm to 950 nm) have been used for photopolymerization in both industrial and medical applications, such as dental curing, microlithography, stereolithography, microelectronics, holography, additive manufacturing, and 3D bioprinting [1][2][3][4][5][6][7][8][9][10][11]. Recently, copper complexes have been used as a new polymerization approach enabling the formation of acetylacetonate radicals by redox reaction to initiate the free radical polymerization (FRP) of acrylates or the free radical promoted cationic polymerization (CP) of epoxides [12][13][14][15][16]. ...
... 7. As reported by van der Laan et al. [7], photoinhibitor in a two-color system is strongly monomer-dependent, which also requires: (i) a high conversion of blue-photoinitiation in the absence of the UV-active inhibitor; (ii) a strong chain termination with significant reduction of blue and UV conversion in the presence of UV-active inhibitor and (iii) short induction time or rapid elimination of the inhibitor species in the dark (or absence of UV-light). Conversion efficiency may be also improved by reduction of the oxygen inhibition effect [9,10,12]. ...
The kinetics and the conversion features of two 3-component systems (A/B/N), based on the proposed new kinetic schemes of Mokbel and Mau et al, in which a visible LED is used to excite a copper complex to its excited triplet state (G*). The coupling of G* with iodonium salt and ethyl 4-(dimethylamino)benzoate (EDB) produces both free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using various new copper complex as the initiator. Higher FRP and CP conversion can be achieved by co-additive of [B] and N, via the dual function of (i) regeneration [A], and (ii) generation of extra radicals. The interpenetrated polymer network (IPN) capable of initiating both FRP and CP in a blend of TMPTA and EPOX. The synergic effects due to CP include: (i) CP can increase viscosity limiting the diffusional oxygen replenishment; (ii) the cation also acts as a diluting agent for the IPN network, and (iii) the exothermic property of the CP. The catalytic cycle, synergic effects, and the oxygen inhibition are theoretically confirmed to support the experimental hypothesis. The measured results of Mokbel and Mau et al are well analyzed and matching the predicted features of our modeling.
... Both spatial and temporal controlled 3D processes were reported using single-and multiple-wavelength lights. For 3D photo printings, the key factors include polymerization depth, resolution precision, and speed, in which the monomer conversion efficacy could be improved by various strategies [12][13][14][15][16][17][18]. They include (i) a thiol-Michael/acrylate hybrid, epoxy/acrylate curable resins, thiol-acrylate/thiol-acetoacetate thermosets, and thiol-ene/epoxy-based polymers [12][13][14]; (ii)the use of novel materials as enhancers or co-initiators in both single and multiple components [15][16][17]; and (iii) twostage polymerization under two wavelengths to eliminate the oxygen inhibition effects [17][18][19]. ...
... For 3D photo printings, the key factors include polymerization depth, resolution precision, and speed, in which the monomer conversion efficacy could be improved by various strategies [12][13][14][15][16][17][18]. They include (i) a thiol-Michael/acrylate hybrid, epoxy/acrylate curable resins, thiol-acrylate/thiol-acetoacetate thermosets, and thiol-ene/epoxy-based polymers [12][13][14]; (ii)the use of novel materials as enhancers or co-initiators in both single and multiple components [15][16][17]; and (iii) twostage polymerization under two wavelengths to eliminate the oxygen inhibition effects [17][18][19]. ...
... However, the UV wavelength suffers the disadvantages of being unsafe to skin and eyes, having a small penetration depth, and larger light scattering in tissues [1,2]. Camphorquinone (CQ), due to its good visible absorption properties, is the most common type-II free radical photopolymerization of (meth-) acrylates under blue light [15,20]. The classical diaryliodonium salts, such as diaryliodonium, suffer low solubility in monomers and the formation of side products due to the release of HF. ...
The synergic features and enhancing strategies for various photopolymerization systems are reviewed by kinetic schemes and the associated measurements. The important topics include (i) photo crosslinking of corneas for the treatment of corneal diseases using UVA-light (365 nm) light and riboflavin as the photosensitizer; (ii) synergic effects by a dual-function enhancer in a three-initiator system; (iii) synergic effects by a three-initiator C/B/A system, with electron-transfer and oxygen-mediated energy-transfer pathways; (iv) copper-complex (G1) photoredox catalyst in G1/Iod/NVK systems for free radical (FRP) and cationic photopolymerization (CP); (v) radical-mediated thiol-ene (TE) photopolymerizations; (vi) superbase photogenerator based-catalyzed thiol−acrylate Michael (TM) addition reaction; and the combined system of TE and TM using dual wavelength; (vii) dual-wavelength (UV and blue) controlled photopolymerization confinement (PC); (viii) dual-wavelength (UV and red) selectively controlled 3D printing; and (ix) three-wavelength selectively controlled in 3D printing and additive manufacturing (AM). With minimum mathematics, we present (for the first time) the synergic features and enhancing strategies for various systems of multi-components, initiators, monomers, and under one-, two-, and three-wavelength light. Therefore, this review provides not only the bridging between modeling and measurements, but also guidance for further experimental studies and new applications in 3D printings and additive manufacturing (AM), based on the innovative concepts (kinetics/schemes).
... Light sources (lasers, LED or lamps) having light spectra ranging from UV (365 nm), visible (430 nm to 660 nm) to near infrared (750 nm to 950 nm) have been used for photopolymerization in both industrial and medical applications, such as dental curing, microlithography, stereolithography, microelectronics, holography, additive manufacturing, and 3D bioprinting [1][2][3][4][5][6][7][8][9][10][11]. Recently, copper complexes have been used as a new polymerization approach enabling the formation of acetylacetonate radicals by redox reaction to initiate the free radical polymerization (FRP) of acrylates or the free radical promoted cationic polymerization (CP) of epoxides [12][13][14][15][16]. ...
. This article presents, for the first time, the kinetics and the general conversion features of a 3-component system (A/B/N), based on proposed mechanism of Mau et al, for both free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using various new copper complex (G2) as the initiator. Higher FRP and CP conversion can be achieved by co-additive of [B] and N, via the dual function of (i) regeneration [A], and (ii) generation of extra radicals. The FRP and CP conversion efficacy (CE) are proportional to the nonlinear power of bI[A][B], where b and I are the effective absorption coefficient and the light intensity, respectively. In the interpenetrated polymer network (IPN) capable of initiating both FRP and CP in a blend of TMPTA and EPOX, (as the monomer for FRP and CP, respectively), the synergic effects due to CP include:: (i) CP can increase viscosity limiting the diffusional oxygen replenishment, such that oxygen inhibition effects are reduced; (ii) the cationic monomer also acts as a diluting agent for the IPN network , and (iii) the exothermic property of the CP. Many new findings are explored via our analytical formuals include: (i) the CE of FRP is about twice of the CE of CP, due to the extra radicals involved in FRP; (ii) the catalytic cycle enhancing the efficacy is mainly due to the regenaration of the initiator, and (iii) the nonlinear dependence of light intensity of the CE (in both FRP and CP). For the first time, the catalytic cycle, synergic effects, and the oxygen inhibition are theoretically confirmed to support the experimental hypothesis. The measured results of Mau et al are well analyzed and matching the predicted features of our modeling. .
... Many publications have been reported about the beneficial effect of onium salts on the properties of the final dental product obtained by free radical photopolymerization [79,130,138,147,184,205,206,[208][209][210][211][212][213][214][215][216]. Researchers from Brazil in 2007 showed that the addition of onium salt improves the polymerization kinetics in dental adhesive resin. ...
... This work demonstrates that enhanced polymerization performances were achieved for the CQ/amine/AY system compared to the reference CQ/amine system. Besides, these PISs showed good bleaching properties after polymerization, and interestingly, excellent initiating ability in strongly oxygen-inhibited conditions [211]. improve dentin bonding performance [205] 1 mol% CQ + 1 mol% EDAB + 1 mol% DPIHFP 0.5 mol% CQ + 1 mol% EDAB + 0.5 mol% BAPO + 1 mol% DPIHFP 0.5 mol% CQ + 1 mol% EDAB + 0.5 mol% PPD + 1 mol% DPIHFP 1 mol% BAPO + 1 mol% EDAB + 1 mol% DPIHFP 1 mol% PPD + 1 mol% EDAB + 1 mol% DPIHFP 1 mol% CQ + 1 mol% EDAB 0.5 mol% CQ + 1 mol% EDAB + 0.5 mol% BAPO 0.5 mol% CQ + 1 mol% EDAB + 0.5 mol% PPD 1 mol% BAPO + 1 mol% EDAB 1 mol% PPD + 1 mol% EDAB increase the degree of conversion, microhardness and push-out bond strength [206] 0.5 mol% CQ + 0.5 mol% DPI 1.0 mol% CQ + 0.5 mol% DPI 0.5 mol% PPD + 0.5 mol% DPI 1.0 mol% PPD + 0.5 mol% DPI 0.5 mol% CQ + 1 mol% DPI 1.0 mol% CQ + 1 mol% DPI 0.5 mol% PPD + 1 mol% DPI 1.0 mol% PPD + 1 mol% DPI 0.5 mol% CQ + 0.5 mol% PPD + 0.5 mol% DPI 0.5 mol% CQ + 1.0 mol% PPD + 0.5 mol% DPI 1.0 mol% CQ + 0.5 mol% PPD + 0.5 mol% DPI 1.0 mol% CQ + 1.0 mol% PPD + 0.5 mol% DPI 0.5 mol% CQ + 0.5 mol% PPD + 1 mol% DPI 0.5 mol% CQ + 1.0 mol% PPD + 1 mol% DPI 1.0 mol% CQ + 0.5 mol% PPD + 1 mol% DPI 1.0 mol% CQ + 1.0 mol% PPD + 1 mol% DPI 0.5 mol% CQ 1.0 mol% CQ 0.5 mol% PPD 1.0 mol% PPD 0.5 mol% CQ + 0.5 mol% PPD 0.5 mol% CQ + 1.0 mol% PPD 1.0 mol% CQ + 0. IS3-bis(4-tert-butylphenyl) iodonium p-toluenesulfonate; IS4-3,5-dichlorophenyl)(2,4,6-trimethoxyphenyl)iodonium p-toluenesulfonate; IS5-bis(4-fluorophenyl)iodonium trifluoromethanesulfonate (IS5); CQ-camphorochinone; EDAB/ETDA-dimethylaminoethyl amine benzoate; PPD-1-phenyl-1,2-propanedione; BAPO-phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide; Ph 3 GeH-triphenylgermanium hydride; BARB-1,3-diethyl-2-thio-barbituric acid; QTX-2-hydroxy-3-(3,4dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride; SULF-p-toluenesulfinic acid sodium salt hydrate; DMAEMA-2-dimethylaminoethyl methacrylate; NapTS-sodium p-toluenesulfinate; NaMeSP-sodium 1-methyl 3-sulfinopropanoate; ZnBnS zinc benzylsulfinate; NaAcABS-sodium 4-(acetylamino)benzenesulfinat; ZniPrS-zinc isopropylsulfinate; NaBuNS-sodium butylnaphtalenesulfinate; NapTSo-sodium p-toluenesulfonate; DPPBS-sodium 3-(diphenylphophino)benzenesulfonate. ...
The photoinduced polymerization of monomers is currently an essential tool in various industries. The photopolymerization process plays an increasingly important role in biomedical applications. It is especially used in the production of dental composites. It also exhibits unique properties, such as a short time of polymerization of composites (up to a few seconds), low energy consumption, and spatial resolution (polymerization only in irradiated areas). This paper describes a short overview of the history and classification of different typical monomers and photoinitiating systems such as bimolecular photoinitiator system containing camphorquinone and aromatic amine, 1-phenyl-1,2-propanedione, phosphine derivatives, germanium derivatives, hexaarylbiimidazole derivatives, silane-based derivatives and thioxanthone derivatives used in the production of dental composites with their limitations and disadvantages. Moreover, this article represents the challenges faced when using the latest inventions in the field of dental materials, with a particular focus on photoinitiating systems based on iodonium salts. The beneficial properties of dental composites cured using initiation systems based on iodonium salts have been demonstrated.
... However, the UV wavelength suffers the disadvantages of being unsafe to skin and eyes, small penetration depth and larger light scattering in tissues [1]. Camphorquinone (CQ), due to its good visible absorption properties, is the most common type-II PI of (meth)acrylates under visible light [4][5][6][7][8]. The first three-component system of (CQ)/amine/ (aryliodonium ylides) was reported by Kirschner et al. [8]. ...
... Camphorquinone (CQ), due to its good visible absorption properties, is the most common type-II PI of (meth)acrylates under visible light [4][5][6][7][8]. The first three-component system of (CQ)/amine/ (aryliodonium ylides) was reported by Kirschner et al. [8]. ...
For the first time, this study presents the detailed kinetics, and modeling the conversion efficacy associated with the experimental results of Bonardi et al. The dual function of the enhancer additive includes: (i) regenerating the photoinitiator, and (ii) producing extra reactive radical. The temporal profiles of the concentration of each of the 3-component system and the associate conversion efficacy are numerically produced. In this study, several new findings showing unique features of various factors influencing the conversion will be demonstrated. For examples, reverse trends (roles) are found in: (i) the light intensity and enhancer concentration, and (ii) the coupling rate constants of radical-oxygen and radical-monomer. The monomer conversion is an increasing function of enhancer, oxygen concentration, and the light intensity. However, they have significantly different steady state features. The steady-state conversion increases from 10% without the enhancer (with enhancer concentration [B]0 =0) to (30%, 50%, 80%) for [B]0=(0.5, 1.0, 2.0)%. High conversion also requires a long lifetime of the free radical. Finally, the measured conversion profiles at various conditions reported by Bonardi et al [19] are compared and analyzed by our modeling.
... Real-time infrared spectroscopy (real-time-FT-IR) is also a common method used to monitor the fading of absorption bands at a given wavenumber corresponding to the bands of a specific function group [12]. This method, because of its short response time, can be used to determine the conversion rates of very quickly polymerising systems [13]. It does, however, have, certain limitations, such as sensitivity to humidity in the room or measurement chamber, or sensitivity to the presence of oxygen. ...
The applicability of new 1,6-diphenylquinolin-2-oneas derivatives as fluorescent molecular sensors for monitoring the progress of photopolymerisation processes by Fluorescence Probe Technique (FPT) has been tested. The progress of cationic, free-radical and thiol-ene photopolymerisation for commercially available monomers: triethylene glycol divinyl ether (TEGDVE), trimethylolpropane triacrylate (TMPTA) and trimethylpropane tris(3-mercaptopropropionate) (MERCAPTO) was monitored. It was found that new derivatives of 1,6-diphenylquinolin-2-one shifted their fluorescence spectra towards shorter wavelengths with the progress of polymerisation, which enabled monitoring the progress in terms of fluorescence intensity ratios as the progress indicator. Derivatives of 1,6-diphenylquinolin-2-one show sensitivity to changes in both polarity and viscosity in the surrounding microenvironment during photopolymerisation processes. Therefore, it was shown that they are good candidates to act as fluorescent sensors for monitoring the kinetics of very quick processes, such as photopolymerisation processes. Furthermore, the effect of the nature of substituents attached to the 1,6-diphenylquinolin-2-one ring on the characteristics of emission spectra was identified. Moreover, the sensitivity of fluorescent sensors was compared with commercially available model sensors, such as 7-diethylamino-4-methylcoumarin (Coumarin 1) and trans-2-(2′,5′-dimethoxyphenyl)ethenyl-2,3,4,5,6-pentafluorobenzene (25ST). Moreover, it was also proven that selected derivatives of 1,6-diphenylquinolin-2-one exhibit an accelerating effect on the progress of cationic photopolymerisation of vinyl monomers (TEGDVE). Thus, the new 1,6-diphenylquinolin-2-one derivatives can be successfully used both as molecular fluorescence sensors to monitor the progress of photopolymerisation processes and as diaryliodonium salt photosensitisers to initiate cationic photopolymerisation processes in a UV-A range of 365 nm.
La polymérisation par voie photochimique prend de plus en plus d’ampleur dans les domaines académiques et industriels de par ses avantages par rapport à la polymérisation thermique. En effet, contrairement à son homologue thermique, la polymérisation photochimique permet un contrôle spatial mais également temporel, la polymérisation n’ayant lieu qu’au court de l'irradiation et dans les zones choisies. De plus, cette voie de synthèse est, la plupart du temps, plus rapide que pour la polymérisation thermique. La polymérisation par voie photochimique nécessite moins d’énergie que celle par voie thermique. Ainsi, le choix de la voie photochimique plutôt que thermique prend tout son sens dans un contexte mondial où l’empreinte carbone devient l’une des préoccupations industrielles majeures lors de la mise en place de nouveaux procédés. La photopolymérisation est donc déjà présente dans de nombreux secteurs tels que le bâtiment, l’automobile, la dentisterie, l’impression 3D… Mais les recherches doivent encore être poursuivies afin que cette méthode réponde aussi bien aux critères industriels qu'environnementaux actuels. De multiples recherches ont déjà été menées sur la polymérisation par voie photochimique. Cependant la plupart des systèmes photoamorceurs (PA) développés sont efficaces sous radiation ultraviolette qui demeurent nocives pour l’utilisateur ce qui empêchent ainsi leur utilisation dans certains domaines dont notamment les applications médicales (dentisterie ou pansements chirurgicaux par exemple). De plus, les sources de radiations UV sont la plupart du temps énergivores ce qui va à l’encontre de la tendance actuelle de réduction drastique des coûts énergétiques. Ainsi, le développement depuis plusieurs années de nouvelles sources d’irradiation - telles que les diodes électroluminescentes – moins énergétiques (et de moins en moins chères) et avec une plus grande durée de vie a permis de relancer et réveiller l’intérêt des industriels pour la photopolymérisation. Il est donc nécessaire de développer de nouveaux systèmes photoamorceurs pour le domaine du visible.En se décalant vers les longueurs d’ondes visible, l’énergie fournie au système photoamorceur pour créer des espèces réactives (telles que des radicaux dans le cas de la polymérisation radicalaire) est moins importantes. En conséquent pour que le système photoamorceur mis en place soit efficace et puisse rivaliser avec les systèmes PA conventionnels, deux stratégies peuvent être envisagées. La première consiste à former plus d’espèces réactives notamment par l’emploi de système catalytique – c’est le cas des approches par catalyse photo-redox par exemple. Tant dis que la seconde stratégie est de jouer sur la nature des espèces réactives formées. En effet, une meilleure réactivité de ces dernières peut compenser la perte d’énergie perçue par le système PA. Les travaux de cette thèse visent notamment à développer de nouveaux systèmes PA en s’appuyant sur cette dernière stratégie. [...]
Photopolymerization is a very popular technique used in the production of various polymeric materials. The key role in light-induced polymerization processes is played by a photoinitiator. One of the most common and desirable activators of photopolymerization is a dye-based photoinitiating system. Most often, these systems are composed of photosensitizer and other additives, such as co-initiators. The dye (photosensitizer) absorbs the irradiation selectively and interacts with other molecules to form reactive species that initiate a chain reaction. For this reason, design and development of novel photosensitizers, and hence photoinitiators, is crucial to improving the efficiency of photochemically initiated polymerization reactions. In recent years, an interesting group of light absorbers, i.e. squaraines, has been proposed as highly efficient photosensitizers. These dyes show excellent spectral properties, such as high molar extinction coefficients and a wide absorption range, which is one of the most important requirements of an effective photosensitizer. Therefore, it is worth paying attention to the high potential of squaraines for photoinitiation of polymerization reactions. In this review we summarized our recent reports on photoinitiating systems containing squarylium dyes for radical polymerization of acrylate monomers. We focused on the radical photoinitiators consisting of 1,3-bis(p-substituted phenylamino)squaraines in the role of sensitizers. The article highlights the development and progress of squaraine-based photoinitiators.
A self-lubricating hydrogel filament was achieved by establishing an in situ photocuring system and using camphorquinone/diphenyl iodonium hexafluorophosphate (CQ/DPI) as the blue-light photoinitiators, acrylamide (AM) and N,N-dimethylacrylamide (DMAA) as the monomers, polyethylene glycol diacrylate (PEGDA) as the cross-linker, and lecithin as the lipid lubricant. The blue-light photopolymerization efficiency and the photorheological properties of the hydrogel precursor were investigated by photodifferential scanning calorimetry and a photorheological system. With the increase of DMAA, the photopolymerization efficiency of the precursor improved, while the elasticity of poly(DMAA/AM) decreased accordingly. The physical cross-linking effect between lecithin and the poly(DMAA/AM) network led to improved polymerization properties and elasticity. The lipid-based boundary layer at the hydrogel surface endowed the self-lubrication of the hydrogel filament. The extruded hydrogel filaments exhibited excellent mechanical properties and weavability, which were expected to play a realistic role in soft robots and bioengineering.
