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Jacques Lalevée - One of the best experts on this subject based on the ideXlab platform.
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a water soluble and highly reactive bisphosphonate functionalized thioxanthone based Photoinitiator
European Polymer Journal, 2020Co-Authors: Tugce Nu Ere, Jacques Lalevée, Turka Gencoglu, Mira Abdallah, Duygu AvciAbstract:Abstract A new water soluble bisphosphonate functionalized thioxanthone (TXBP2) is synthesized from aza-Michael addition reaction of 2-(2-aminoethoxy)-9H-thioxanthen-9-one and tetraethyl vinylidene bisphosphonate. This Photoinitiator shows excellent water-solubility of 86 g L−1 compared to Irgacure 2959 (5 g L−1). It has a λmax in the near UV–visible region, ~400 nm. The photoinitiation effectiveness of TXBP2 is studied by photo-DSC for photopolymerization of trimethylolpropane triacrylate and poly(ethylene glycol) diacrylate (PEGDA, Mn = 575 D). It shows very high polymerization rates and conversions with bis-(4-tert-butylphenyl)-iodonium hexafluorophosphate or ethyl 4-(dimethylamino)benzoate, compared to thioxanthone. The photochemical mechanisms investigated by laser flash photolysis and fluorescence indicate that the reaction involves both singlet and triplet pathway. Water solubility, biocompatibility and high reactivity make this Photoinitiator a promising candidate for biomedical applications.
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different nir dye scaffolds for polymerization reactions under nir light
Polymer Chemistry, 2019Co-Authors: Didier Gigmes, Jean-pierre Fouassier, Audeheloise Bonardi, Celine Dietlin, Guillaume Noirbent, Fabrice Bonardi, Frédéric Dumur, Jacques LalevéeAbstract:In this article, near-infrared dyes of different structures have been investigated as new Photoinitiators/photosensitizers for the free radical polymerization (FRP) of methacrylates upon Near InfraRed (NIR) light exposure using a laser diode @785 nm, @940 nm and @1064 nm. Interestingly, the use of squaraine, squarylium, boron-pyrromethene and porphyrin derivatives as efficient Photoinitiators is clearly highlighted. These dyes are used in combination with an iodonium salt and a phosphine. Additionally, a thermal initiator can be added to the resin to take advantage of the photothermal effect, i.e., to the heat release during the polymerization process, so that polymerization kinetics could be greatly improved compared to the pure photochemical mode. These dyes can be proposed as alternatives to the well-established cyanine dyes, more commonly used for the photopolymerization of (meth)acrylates under NIR light.
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thioxanthone functionalized 1 6 heptadiene as monomeric Photoinitiator
Progress in Organic Coatings, 2019Co-Authors: Tugce Nu Ere, Jacques Lalevée, Ernadette Graff, Duygu AvciAbstract:Abstract The synthesis of the first Photoinitiator (PI) based on thioxanthone (TX) with 1,6-heptadiene structure is described. This PI (TXdMA) absorbs in the near UV–vis region (435–439 nm; with absorption redshift≈50 nm and e values comparable to TX). Photopolymerization results demonstrate that although TXdMA is not an effective one-component polymerizable Photoinitiator, it can successfully initiate photopolymerization of poly(ethylene glycol) diacrylate (PEGDA, Mn = 250 D) and trimethylolpropane triacrylate (TMPTA) in the presence of bis-(4-tert-butylphenyl)-iodonium hexafluorophosphate (Iod) similar to TX/Iod. TXdMA exhibits better migration stability than TX. Absorption, fluorescence, steady state photolysis and cyclic voltammetry experiments are carried out to investigate the photochemical mechanisms.
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carbazole scaffold based Photoinitiator photoredox catalysts toward new high performance photoinitiating systems and application in led projector 3d printing resins
Macromolecules, 2017Co-Authors: Assi Al Mousawi, Didier Gigmes, Frederic Dumu, Patxi Garra, Joumana Toufaily, Tayssi Hamieh, Ernadette Graff, Jeanpierre Fouassie, Jacques LalevéeAbstract:Four new carbazole derivatives (C1–C4) are synthesized and proposed as high performance visible light Photoinitiators/photoredox catalysts for both the free radical polymerization (FRP) of (meth)acrylates and the cationic polymerization (CP) of epoxides upon visible light exposure using light-emitting diodes (LEDs) at 405, 455, and 477 nm. Excellent polymerization initiating abilities are found, and high final reactive function conversions are obtained. Interestingly, these new derivatives exhibit much better visible light polymerization initiating ability compared to a reference UV-absorbing carbazole (CARET, 9H-carbazole-9-ethanol) showing that the new substituents are of great interest to red-shift the absorption of the proposed Photoinitiators. More remarkably, in combination with an iodonium salt, C1–C4 are also better than the well-known bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (BAPO) Photoinitiator for mild irradiation conditions highlighting their outstanding reactivity. Their use in new c...
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zinc tetraphenylporphyrin as high performance visible light Photoinitiator of cationic photosensitive resins for led projector 3d printing applications
Macromolecules, 2017Co-Authors: Assi Al Mousawi, Frederic Dumu, Joumana Toufaily, Tayssi Hamieh, Jeanpierre Fouassie, Cyril Poriel, Jacques LalevéeAbstract:Zinc tetraphenylporphyrin (ZnTPP) is proposed as a high performance visible light Photoinitiator for both the free radical polymerization (FRP) of methacrylates (thick films) and the cationic polymerization (CP) of epoxides (thin films) upon visible light exposure using light emitting diodes (LEDs) at 405, 455, 477, and 530 nm. ZnTPP combined with an iodonium salt shows excellent polymerization initiating abilities and high final conversions were obtained. Remarkably, for the ligand alone (tetraphenylporphyrin derivative, H2TPMP) used as Photoinitiator, no polymerization occurs, indicating the importance of the metal in the initiating complex for an efficient process. A full picture of the involved chemical mechanisms is given. The high performance of ZnTPP as cationic initiating system is also well shown for new cationic 3D printing resins upon exposure to LED projector at 405 nm.
Yusuf Yagci - One of the best experts on this subject based on the ideXlab platform.
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poly vinyl alcohol thioxanthone as one component type ii Photoinitiator for free radical polymerization in organic and aqueous media
Macromolecular Rapid Communications, 2015Co-Authors: Senem Kork, Yusuf Yagci, Gorkem YilmazAbstract:A novel one-component type II polymeric Photoinitiator, poly(vinyl alcohol)-thioxanthone (PVA-TX), is synthesized by a simple acetalization process and characterized. PVA-TX enables photopolymerization of methyl methacrylate and acrylamide in both organic and aqueous media. Photopolymerization proceeds even in the absence of a co-initiator since PVA-TX possesses both chromophoric and hydrogen donating sites in the structure.
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thioxanthone ethylcarbazole as a soluble visible light Photoinitiator for free radical and free radical promoted cationic polymerizations
Polymer Chemistry, 2011Co-Authors: Deniz Tunc, Yusuf YagciAbstract:Thioxanthone-ethylcarbazole (TX-EC), 7-ethylthiochromeno[2,3-b]carbazol-13(7H)-one, as a novel visible light absorbing one-component Type II Photoinitiator with high solubility, was synthesized and characterized. Its ability to initiate free radical photopolymerization of methyl methacrylate (MMA) was demonstrated and compared with that of the parent thioxanthone-carbazole (TX-C) both in the presence and absence of a co-initiator. It is found that TX-EC is a more effective Photoinitiator in all cases. The mechanism of initiating radical formation for free radical polymerization in the absence of an added co-initiator involves photoexcitation of TX-EC and hydrogen abstraction of triplet states of TX-EC from the ethyl group attached to the carbazole moiety. In the presence of triethyl amine, the corresponding hydrogen abstraction reaction occurs between a triplet Photoinitiator and the amine compound. The possibility of visible light photoinitiation of free radical promoted cationic polymerization of several monomers, namely cyclohexene oxide (CHO), n-butyl vinylether (BVE), N-vinyl carbazole (NVC) and 3,4-epoxycyclohexyl-3′,4′-epoxycyclohexene carboxylate (EEC) using TX-EC and Ph2I+PF6− combination was also demonstrated.
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poly ethylene glycol thioxanthone prepared by diels alder click chemistry as one component polymeric Photoinitiator for aqueous free radical polymerization
Journal of Polymer Science Part A, 2010Co-Authors: Haka Aka, Nergis Arsu, Demet Karaca Alta, Urci Gacal, Yusuf YagciAbstract:ABSTRACT: Novel water-borne macroPhotoinitiator containingthioxanthone (TX) end group was successfully synthesized byusing Diels–Alder (DA) [4 þ 2] click chemistry strategy. For thispurpose, thioxanthone-anthracene (TX-A) and maleimide end-functionalized poly(ethylene glycol) (PEG-MI) were reacted intoluene at reflux temperature for 48 h. The final polymer (PEG-TX) and the intermediates were characterized in detail by spec-tral analysis. PEG-TX possesses absorption characteristics simi-lar to the parent TX. The one-component photoinitiating natureof the photointiator was demonstrated by photopolymeizationof several hydrophilic vinyl monomers, such as acrylic acid,acrylamide, 2-hydroxyethyl acrylate, and 1-vinyl-2-pyrrolidone. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem48: 2109–2114, 2010 KEYWORDS: aqueous free-radical polymerization; click chemis-try; Diels–Alder cycloaddition; macroPhotoinitiator; photopoly-merization; thioxanthoneINTRODUCTION There has been revitalized interest in thedevelopment and applications of novel polymeric photoinitia-tors. This is mainly associated with the advantages derivedfrom their macromolecular nature. In comparison with theirlow-molecular weight analogues, the presence of the polymerchain in the polymeric Photoinitiator in many cases improvescompatibility in the formulation and reduces the migrationonto the film surface. Moreover, odor and toxicity problemsdo not occur with macroPhotoinitiators owing to the lowvolatility of the large molecules. Polymeric Photoinitiatorscan be defined as macromolecular systems that possesschromophoric groups either in the main or side chain, whichmay be accomplished in two ways: (i) synthesis and poly-merization of monomers with photoreactive groups and (ii)introduction of photoactive groups into polymer chains. Inthe latter case, macroPhotoinitiators were synthesized byusing functional initiators and terminators in a particularpolymerization or by reacting functional groups of a pre-formedpolymer with other functional groupsof low-molecularweight compounds possessing also photoreactive groups.MacroPhotoinitiators, analogous to the low-molecular weightPhotoinitiators, are divided into two classes, accordingto their radical generation mechanism, namely cleavage-type (Type I) and hydrogen abstraction-type (Type II)macroPhotoinitiators.
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sequential photodecomposition of bisacylgermane type Photoinitiator synthesis of block copolymers by combination of free radical promoted cationic and free radical polymerization mechanisms
Journal of Polymer Science Part A, 2009Co-Authors: Yasemin Yuksel Durmaz, Manolya Kukut, Norbert Moszner, Yusuf YagciAbstract:A block copolymer of cyclohexene oxide (CHO) and styrene (St) was pre- pared by using bifunctional visible light Photoinitiator dibenzoyldiethylgermane (DBDEG) via a two-step procedure. The bifunctionality of the Photoinitiator pertains to the sequential photodecomposition of DBDEG through acyl germane bonds. In the first step, photoinitiated free radical promoted cationic polymerization of CHO using DBDEG in the presence of diphenyliodonium hexafluorophosphate (Ph2I þ PF � ) was carried out to yield polymers with photoactive monobenzoyl germane end groups. These poly(cyclohexene oxide) (PCHO) prepolymers were used to induce photoiniti- ated free radical polymerization of styrene (St) resulting in the formation of poly- (cyclohexene oxide-block-styrene) (P(CHO-b-St)). Successful blocking has been con- firmed by a strong change in the molecular weight of the prepolymer and the block copolymer as well as NMR, IR, and DSC spectral measurements. V C 2009 Wiley
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diethoxy azobis pyridinium salt as Photoinitiator for cationic polymerization towards wavelength tunability by cis trans isomerization
Macromolecular Rapid Communications, 2008Co-Authors: Yasemin Yuksel Durmaz, Omer Zaim, Yusuf YagciAbstract:N,N'-diethoxy-4,4'-azobis(pyridinium) hexafluorophosphate (DEAP) has been synthesized by alkylation of the corresponding N-oxide and characterized. DEAP exhibits UV induced cis-trans isomerization with absorptions at around λ = 459 and 360 nm, respectively. The ability of the DEAP ion to act as a Photoinitiator for the cationic polymerization of cyclohexene oxide and N-vinylcarbazole is demonstrated. The initiation step involves the decay of the excited state of the trans form of the salt with homolytic bond rupture of the nitrogen-oxygen bond. Its potential use as a Photoinitiator for free radical polymerization is also demonstrated using methyl methacrylate monomer as the example.
Nergis Arsu - One of the best experts on this subject based on the ideXlab platform.
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thioxanthone benzothiophenes as Photoinitiator for free radical polymerization
Journal of Photochemistry and Photobiology A-chemistry, 2016Co-Authors: Nurcan Karaca, Nergis Arsu, Nuket Ocal, Steffe JockuschAbstract:Abstract Photoinitiators for free radical polymerization based on the thioxanthone chromophore that contains benzothiophene were synthesized and characterized. Compared to thioxanthone, these compounds show a bathochromic shifted absorption up to ∼460 nm. High quantum yields for intersystem crossing generate sufficient amounts of triplet states. Initiator radicals are generated by reaction of the triplet states with tertiary amines, such as diethanolamine with high rate constants (2–6 × 10 9 M −1 s −1 ) as determined by laser flash photolysis. Photoinitiated polymerization experiments of MMA showed efficient polymerization with initiator concentrations as low as 0.1 mM.
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panchromatic type ii Photoinitiator for free radical polymerization based on thioxanthone derivative
Macromolecules, 2013Co-Authors: Duygu Sevinc Ese, Nergis Arsu, Meral Aydi, C Ley, Xavie AllonasAbstract:A new Photoinitiator for free radical photopolymerization, belonging to the thioxanthone derivatives, was synthesized and characterized. It was found that the compound absorbs over the whole UV–vis spectrum with relatively high absorption coefficients. Fluorescence studies reveal that three different singlet excited states are responsible for this absorption. Phosphorescence and laser flash photolysis evidence the formation of a triplet state from which a photoreduction can occur. Consequently, initiating radicals were formed which are able to initiate the photopolymerization of methyl methacrylate in DMF. Finally, the photopolymerization of acrylates was performed in film at different wavelengths such as 392, 476, 532, and 632 nm, emphasizing the possibility to use this novel Photoinitiator when panchromatic irradiation is required.
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benzoin type Photoinitiator for free radical polymerization
Journal of Polymer Science Part A, 2013Co-Authors: Duygu Sevinc Ese, Nergis Arsu, Steffe Jockusch, Jose P Da Silva, Nicholas J TurroAbstract:Benzoin, a popular Photoinitiator for free radical polymerization of vinyl monomers, was improved by intro- duction of two methyl thioether substituents. This new ben- zoin derivative showed an about 50 times higher light absorption in the near-UV spectral region and performed bet- ter than the unsubstituted benzoin in polymerization experi- ments in bulk solutions or films of acrylate monomers when low initiator concentrations are used. Laser flash photolysis, low temperature luminescence experiments and photoproduct studies by mass spectrometry suggest that a slow a-cleavage mechanism (ka ¼ 2.2 � 10 5 s � 1 ) from the electronic triplet state with a quantum yield of 0.1 is the primary photoreac- tion to generate the initiating free radicals. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 1865-1871 In the presence of vinyl monomers, these radicals can initiate free radical polymerization. The major disadvantage of benzoin and its ether derivatives is the poor light absorption in the near-UV, a spectral region which is most attractive for industrial photopolymerizations. Here, we present a benzoin derivative, MTB, which shows the desired bathochromic shifted absorption and higher molar absorptivity compared to benzoin. We show that although the mechanism of radical generation is different from the a-cleav- age mechanism of unsubstituted benzoin, this new photoini- tiator efficiently initiates free radical polymerization.
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thioxanthone diphenyl anthracene visible light Photoinitiator
Macromolecules, 2012Co-Authors: Demet Karaca Alta, Gokha Temel, Gokce Goksu, Nuke Ocal, Nergis ArsuAbstract:7,12-Diphenyl-14H-naphto[2,3-b]thioxanthen-14-one (TX-DPA) was synthesized and characterized as a potential visible light Photoinitiator for radical polymerization. TX-DPA has an excellent absorption character in the visible region and the photophysical properties of TX-DPA were investigated by fluorescence and laser flash photolysis studies and the photopolymerization of methyl methacrylate in air atmosphere helped to understand the initiation mechanism of TX-DPA. Moreover, it is possible that the production of singlet oxygen from the quenching of 3TX-DPA by molecular oxygen resulted in the reaction of singlet oxygen with TX-DPA to form an endoperoxide: decomposition of endoperoxide leads to initiating radicals.
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a thioxanthone based visible Photoinitiator
Journal of Polymer Science Part A, 2011Co-Authors: Sevnur Keski Dogruyol, Zekeriya Dogruyol, Nergis ArsuAbstract:Thioxanthone-based 9-(2-Morpholine-4yl-acetyl)-5- thia-napthasen-12-one (TX-MPM) was synthesized and charac- terized as a one-component novel visible Photoinitiator. Its capability to act as an initiator for the polymerization of methyl methacrylate (MMA) was examined in photoreactor and also daylight. Photophysical properties: fluorescence and phospho- rescence emission spectra and fluorescence quantum yield of TX-MPM (Uf ¼ 0.29) were determined. The phosphorescence lifetime was found 131 ms for TX-MPM and 110 ms for initia- tor-attached polymer (PMMA) at 77 K, indicated a p!p* nature of the lowest triplet state. A model compound, morpholino acetonapthone was used as quencher for the triplet states of TX- MPM and the quenching rate constant was determined (kq ¼ 1.26 � 10 9 M � 1 s � 1 ). According to laser flash photolysis studies, intermolecular hydrogen abstraction process was more domi- nant path to the formation of the initiating radicals. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4037-4043, 2011
William M Palin - One of the best experts on this subject based on the ideXlab platform.
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increased rates of photopolymerisation by ternary type ii Photoinitiator systems in dental resins
Journal of The Mechanical Behavior of Biomedical Materials, 2019Co-Authors: Adriano Fonseca Lima, Marcos Vinicius Oliveira Salvador, Diogo Dressano, Cintia Helena Coury Saraceni, Luciano De Souza Goncalves, Mohammed A Hadis, William M PalinAbstract:Abstract To evaluate the effects of Type I and Type II Photoinitiator systems on curing efficiency, degree of conversion (DC) and chemico-physical properties of resin based materials. A comonomer base containing 50%wt 2.2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bis-GMA) and 50%wt triethyleneglycol dimethacrylate (TEGDMA) was formulated with either 0.5 or 1mol% of Type II camphoroquinone (CQ), Type I monoacylphosphine oxide (MAPO) or bis-acylphosphine oxide (BAPO) Photoinitiators. The Type II system was either a binary (1: 2 CQ:amine) or ternary system (1: 2 CQ:amine + 0.5 mol% DPI). Degree and rate of polymerization was measured by Fourier Transform Infrared Spectroscopy (FTIR). Knoop micro-hardness prior to and following ethanol immersion was assessed. Flexural strength and modulus was measured under three-point bend test. Water sorption and solubility was also evaluated. The Photoinitiator absorption spectra and the total absorbed energy per unit volume (Eabs) for 0.5mol% Photoinitiator in each material was calculated. Despite the reduced total absorbed energy per unit volume for CQ based systems, ternary Type II system significantly improved curing efficiency (P 0.05). Ternary Type II systems is an efficient alternative to improve the polymerization of resin materials, promoting similar or even better properties than Type I initiators. DPI can increase the reactivity of CQ systems and promote polymerization rates superior than Type I Photoinitiators.
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reduced polymerization stress of mapo containing resin composites with increased curing speed degree of conversion and mechanical properties
Dental Materials, 2014Co-Authors: William M Palin, Mohammed A Hadis, Julian Leprince, Gaetane Leloup, L Boland, Garry J P Fleming, G Krastl, D C WattsAbstract:Abstract Objectives The degree and rate of photopolymerization in resin-based dental composites will significantly affect polymer network formation and resultant material properties that may determine their clinical success. This study investigates the mechanical properties, the generation of stress from polymerization, tooth cusp deflection and marginal integrity of experimental resin composites that contain different Photoinitiators. Methods Experimental light-activated resin composites (60 vol% particulate filled in 50/50 mass% bis-GMA/TEGDMA) were formulated using a monoacylphosphine oxide (MAPO) Photoinitiator and compared with a conventional camphoroquinone (CQ)-based system. Similar radiant exposure was used (18 J cm −2 ) for polymerization of each material although the curing protocol was varied (400 mW cm −2 for 45 s, 1500 mW cm −2 for 12 s and 3000 mW cm −2 for 6 s). Degree and rate of polymerization was calculated in real-time by near infrared spectroscopy and the generation of stress throughout polymerization measured using a cantilever beam method. Flexural strength and modulus were acquired by three-point bend tests. Standardized cavities in extract pre-molar teeth were restored with each material, the total cuspal deflection measured and post-placement marginal integrity between the tooth and restoration recorded. Results Generally, MAPO- exhibited a significantly higher degree of conversion (72 ± 0.8 to 82 ± 0.5%) compared with CQ-based materials (39 ± 0.7 to 65 ± 1.6%) regardless of curing protocol ( p 50% conversion. Higher irradiance polymerization had a significant deleterious effect on the mechanical properties of CQ-based materials ( p −1 for 6 s (10.1 ± 3.5 and 9.0 ± 1.5 μm). A significant decrease in marginal integrity was observed for CQ-based RBCs cured at high irradiance for short exposure time compared with that of the MAPO-based RBC cured using a similar protocol ( p = 0.037). Significance Polymer network formation dictates the final properties of the set composite and the use MAPO Photoinitiators may provide an effective restorative material that exhibits higher curing speeds, increased degree of conversion, strength and modulus without compromise in terms of polymerization stress and marginal integrity between tooth and restoration.
Xuesong Jiang - One of the best experts on this subject based on the ideXlab platform.
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a novel amphipathic polymeric thioxanthone Photoinitiator
Polymer, 2009Co-Authors: Xuesong Jiang, Jue LuoAbstract:Abstract A novel amphipathic polymeric photointiator based on thioxanthone (TX) (APTX) containing coinitiator amine was synthesized by introducing TX, amine and short poly(ethylene oxide) (PEO) chain into the backbone of polymeric chain together. APTX can be not only dispersed easily in many solvents and acrylate monomers but also is soluble in water. In comparison to low-molecular weight analogues Photoinitiators, APTX is very efficient for photoinitiation of acrylate monomers 2,2-bis[4-(acryloxypolyethoxy)phenyl] propane (ABPE-10) and trimethylolpropane triacrylate (TMPTA), and acrylamide (AM) in aqueous solution.
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novel chemical bonded polymerizable sulfur containing Photoinitiators comprising the structure of planar n phenylmaleimide and benzophenone for photopolymerization
Polymer, 2006Co-Authors: Hongyu Wang, Xuesong JiangAbstract:As a continuation of the research on chemical-bonded Photoinitiators comprising the structure of planar N-phenylmaleimide (NPMI) and benzophenone (BP), three novel polymerizable sulfur-containing Photoinitiator MTPBP, CMTPBP and BMTPBP were synthesized by introducing NPMI group into benzophenone (BP). BP was selected as the reference to evaluate their photoefficiency. These novel Photoinitiators possess greatly red-shifted UV maximal absorption, and their fluorescence emission varies. Three representative types of different functionality monomers, methyl methacrylate (MMA), 1,6-hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA), initiated by the three novel Photoinitiators were studied through dilatometer and photo-DSC using unsaturated tertiary amine N,N-dimethylaminoethyl methacrylate (DMAEMA) as the coinitiator. The results show surprising high efficiency of these chemical-bonded Photoinitiators towards different monomers in contrast to BP, and they can initiate photopolymerization without the coinitiator because of the photolysis at C–S bond. The results also verify that the higher viscosity of monomers and the larger molecular size of the Photoinitiators may restrict the bimolecular H-abstraction reaction.
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polymeric Photoinitiator containing in chain thioxanthone and coinitiator amines
Macromolecular Rapid Communications, 2004Co-Authors: Xuesong JiangAbstract:A polymeric Photoinitiator (PTXP) containing in-chain thioxanthone (TX) and coinitiator amines was synthesized by step-growth polymerization, as well as low-molecular-weight model compounds. Photopolymerizations of methyl methacrylate (MMA) initiated by these Photoinitiator systems were studied. Compared with corresponding low-molecular-weight model compounds, PTXP has a similar UV-vis spectrum with a red-shifted maximum absorption, and weaker fluorescence emission, and can photoinitiate the polymerization of MMA more effectively.
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polymeric amine bearing side chain thioxanthone as a novel Photoinitiator for photopolymerization
Polymer, 2004Co-Authors: Xuesong JiangAbstract:Abstract Novel polymeric photoinitator (PTX) was synthesized by introducing thioxanthone (TX) moieties to polymeric amine side-chain. Compared with low-mulecular weight model compound, PTX has similar UV–vis absorption and weaker fluorescence emission, and some radicals are trapped in the macromolecular coil cage. The kinetics for polymerization of trimethylolpropane triacrylate using PTX as Photoinitiator was studied by photo-DSC. It shows that PTX is an efficient Photoinitiator, and that PTX concentration and light intensity have similar effect on photopolymerization. The increase in PTX concentration and light intensity leads to the increase in the polymerization rate and the final conversion. The increase in temperature also results in the increase in the polymerization rate and final conversion, due to the enhanced molecular mobility and delay in vitrification at high temperature. At the late stage of polymerization, the reaction becomes more diffusion-controlled than that at early stage of polymerization.
