Статті в журналах: "Photoinitiator system"

1

Kowalska, Andrea, Jerzy Sokolowski, and Kinga Bociong. "The Photoinitiators Used in Resin Based Dental Composite—A Review and Future Perspectives." Polymers 13, no. 3 (February 2, 2021): 470. http://dx.doi.org/10.3390/polym13030470.

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The presented paper concerns current knowledge of commercial and alternative photoinitiator systems used in dentistry. It discusses alternative and commercial photoinitiators and focuses on mechanisms of polymerization process, in vitro measurement methods and factors influencing the degree of conversion and hardness of dental resins. PubMed, Academia.edu, Google Scholar, Elsevier, ResearchGate and Mendeley, analysis from 1985 to 2020 were searched electronically with appropriate keywords. Over 60 articles were chosen based on relevance to this review. Dental light-cured composites are the most common filling used in dentistry, but every photoinitiator system requires proper light-curing system with suitable spectrum of light. Alternation of photoinitiator might cause changing the values of biomechanical properties such as: degree of conversion, hardness, biocompatibility. This review contains comparison of biomechanical properties of dental composites including different photosensitizers among other: camphorquinone, phenanthrenequinone, benzophenone and 1-phenyl-1,2 propanedione, trimethylbenzoyl-diphenylphosphine oxide, benzoyl peroxide. The major aim of this article was to point out alternative photoinitiators which would compensate the disadvantages of camphorquinone such as: yellow staining or poor biocompatibility and also would have mechanical properties as satisfactory as camphorquinone. Research showed there is not an adequate photoinitiator which can be as sufficient as camphorquinone (CQ), but alternative photosensitizers like: benzoyl germanium or novel acylphosphine oxide photoinitiators used synergistically with CQ are able to improve aesthetic properties and degree of conversion of dental resin.

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2

Hilborn, J., and B. Rånaby. "Photocrosslinking of EPDM Elastomers. Photocrosslinkable Compositions." Rubber Chemistry and Technology 62, no. 4 (September 1, 1989): 592–608. http://dx.doi.org/10.5254/1.3536262.

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Abstract EFDM rubbers can be efficiently crosslinked using multifunctional monomers. Several factors must be taken into consideration: 1. Good solubility of the crosslinking agent in the rubber is essential. 2. It is favorable to have a mechanism of crosslinking which gives an alternating addition of rubber and crosslinking agent, as in the case of the stepwise radical thiol-ene system or alternating copolymerization of bis-maleimide with the olefinic rubber. These systems utilize each radical of the photoinitiator to form crosslinks, enhance the rate of crosslinking and prevent homopolymerization of the crosslinking agent. 3. A good match of the UV absorption of the photoinitiator, the UV transmission of the rest of the system, and the UV emission from the lamp is essential. 4. Since disproportionation of photoinitiator radicals in cage is an unwanted side reaction in the rigid rubber system, it is better to choose photoinitiators that mainly recombine to reform a photoactive molecule as before scission.

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3

Ayub, Nur Farizah, Shahrir Hashim, Jamarosliza Jamaluddin, Roshafima Rasit Ali, and Nadia Adrus. "UV LED Curing Formulation for Polyacrylamide Hydrogels." Advanced Materials Research 1125 (October 2015): 84–88. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.84.

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Current studies showed that UV LED system is a green technology and highly efficient as compared to UV Mercury (UV Hg) system. In this study, the UV LED curing formulations of polyacrylamide (PAAm) hydrogels were developed. The formulations consisted of acrylamide (AAm) as a main monomer,N,N’-methylenebisacrylamide as a crosslinker and photoinitiator. UV LED emits monochromatic light sources only (365 nm or 385 nm). Thus, in order to developed formulation of UV LED curable hydrogels, a suitable water soluble photoinitiator (i.e. λ ~ 365 nm) has to be employed. A commercially available photoinitiator Oligo [2-hydroxy-2-methyl-1-[4-(1-methylvinyl) phenyl] propanone] under the trade name Chivacure 300 (λ ~ 330 nm) was chosen in the first formulations. However, due to limited solubility in water, addition of tetrahydrofuran (THF) at 9.5:0.5 ratio of water/THF was required for Chivacure 300. We also synthesized a photoinitiator based on 2,2-dimethoxy-2-phenyl acetophenone (DMPA) and methylated-β-cyclodextrin (MβCD) to be used in the second formulation. The complexation of DMPA and MβCD resulted in transparent and water-soluble supramolecular-structured photoinitiator (SSPI) (λ ~ 330 nm). Both formulations were irradiated using UV LED system (Hoenle AG, Germany, 365 nm) for 15 min. Synthesis of PAAm hydrogels with both photoinitiators has yielded almost complete conversion of hydrogels (> 80 %). Clearly, this study has revealed that enhanced formulation of UV LED curable hydrogels are due to appropriate choice of excellent water-solubility photoinitiators (Chivacure 300 and modified DMPA). We concluded that UV LED is an important tool for curing hydrogel formulations of various acrylate water-based monomers.

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4

Chen, Lijuan, Fan Chen, Weixin Zhu, Luoyi Chen, Yingyu Liang, and Xiaohui Guo. "Construction of Photoinitiator Functionalized Spherical Nanoparticles Enabling Favorable Photoinitiating Activity and Migration Resistance for 3D Printing." Polymers 14, no. 21 (October 27, 2022): 4551. http://dx.doi.org/10.3390/polym14214551.

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A straight-forward method was exploited to construct a multifunctional hybrid photoinitiator by supporting 2-hydroxy-2-methylpropiophenone (HMPP) onto a nano-silica surface through a chemical reaction between silica and HMPP by using (3-isocyanatopropyl)-triethoxysilane (IPTS) as a bridge, and this was noted as silica-s-HMPP. The novel hybrid-photoinitiator can not only initiate the photopolymerization but also prominently improve the dispersion of nanoparticles in the polyurethane acrylate matrix and enhance the filler-elastomer interfacial interaction, which results in excellent mechanical properties of UV-cured nanocomposites. Furthermore, the amount of extractable residual photoinitiators in the UV-cured system of silica-s-HPMM shows a significant decrease compared with the original HPMM system. Since endowing the silica nanoparticle with photo-initiated performance and fairly lower mobility, it may lead to a reduction in environmental contamination compared to traditional photoinitators. In addition, the hybrid-photoinitiator gives rise to an accurate resolution object with a complex construction and favorable surface morphology, indicating that multifunctional nanosilica particles can be applied in stereolithographic 3D printing.

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5

Xu, Rui Xin, and Guang Xue Chen. "Study on Photopolymerization Performance of Waterborne UV Cured Ink." Advanced Materials Research 174 (December 2010): 401–4. http://dx.doi.org/10.4028/www.scientific.net/amr.174.401.

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The anion UV-curing water soluble prepolymer was synthesized with toluene diisocyanate, dihydroxy compound, dihydroxyalkyl carboxylic acid and polyurethane acrylate. The structure of the prepolymer was characterized by infrared spectroscopy. The effect of different photoinitiators, pigment content, drying technology on the curing speed of ink was also researched. The results shown that the photoinitiator system 819DW and MBF was best matched with the yellow pigment, cyan pigment and black pigment, the optimum content of the pigment was about 10 percent, 10 percent and 11 percent. The photoinitiator system 819DW and 500 was best matched with the magenta pigment, the optimum content of the pigment was about 10 percent．Under the conditions of this experiment, the best pigment content of the yellow, magenta, cyan, black was about 6 percent, 7 percent, 6 percent and 7 percent. The curing rate without pre-drying increased.

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6

Santini, Ario, Iranzihuatl Torres Gallegos, and Christopher M. Felix. "Photoinitiators in Dentistry: A Review." Primary Dental Journal 2, no. 4 (December 2013): 30–33. http://dx.doi.org/10.1308/205016814809859563.

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Polymerization of Resin Based Composites (RBCs) initiated by a light curing unit activating photoinitiators. Different RBCs require different light energy levels for proper curing. Manufacturers are now producing RBCs with more than one initiator and not all of these will be properly polymerised with blue LED lights. An added problem is that manufacturers do not always indicate the type of photoinitiators in their materials. This review discusses the importance of matching the spectral output of LCUs to the absorption spectra of RBCs and the consequences of spectral mismatch. Resin based composites (RBCs) were first introduced in the 1960s1 and with development of effective and reliable dentine bonding systems2, have been used routinely as a filling material for both anterior and posterior teeth. The early RBCs were either chemically cured two component materials or photo-initiated materials that used UV initiators in the beginning and then transitioned to visible light initiators such as camphorquinine which was introduced in 1978.3 The first report of a light curing material was of an ultraviolet (UV) cured fissure sealant.4 However, due to the limited penetration depth of the UV light and the potential health hazards, this system was quickly abandoned. The advancement of science yielded light curing materials which contributed to a significant clinical progress over the UV and chemically cured RBCs.4 Additional advancements to direct RBC restoration materials included luting agents for ceramic restorations, pit and fissure sealants and resin modified glass ionomers. Polymerization in an RBC is initiated by a light curing unit (LCU); this technology is based on the use of photoreactive systems that absorb light irradiation from the LCUs at appropriate wavelength. Then the photoinitiators contained in the RBCs, absorb the incoming photons from the LCU and the monomers in the molecular structure become excited and in that active state, there is a change from monomers into a polymer network6. The success of this technology hinges on matching the spectral emission of the LCU with the requirements of the photoinitiator system to convert the monomers into a polymer network. The amount of activated photo initiator depends on the concentration of photoinitiator in the material, the number of photons to which the material is exposed and the energy of the photons (wavelength), the latter depending on the curing light.6 The most common photoinitiator in dental materials today is camphorquinone, which has a peak activity around 470 nanometres.6 The factors affecting polymerization include filler type, size and loading, the thickness and shade of the restorative material, the effectiveness of light transmission (eg. light guide tips being free from debris and scratches), exposure time, distance of the light source from the restorative material and light intensity.7 It is important to note that the photoinitiator activation occurs at specific wavelengths, in other words, the optimum efficiency is obtained when the peak absorptivity of the photoinitiator corresponds with the spectral emission from the LCU. Commercially available curing units have different light intensities and light sources, with energy levels in QTH, LED and other LCUs ranging from 300 to more than 2000 mW/cm.

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7

Gómez, María L., Carlos M. Previtali, and Hernán A. Montejano. "Two- and Three-Component Visible Light Photoinitiating Systems for Radical Polymerization Based on Onium Salts: An Overview of Mechanistic and Laser Flash Photolysis Studies." International Journal of Photoenergy 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/260728.

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A review of our work on two- and-three component photoinitiator systems is presented. The emphasis is in on visible light polymerization in aqueous media. The systems discussed comprise a synthetic dye as sensitizer and an onium salt as coinitiator, or a dye-amine-onium salt with the amine as coinitiator and the onium salt as an enhancer of the polymerization efficiency. The effect of the composition of the system on the photopolymerization kinetics was analyzed. To this end, the photophysics and photochemistry of the dye under polymerization conditions was explored by means of stationary and time-resolved spectroscopic methods. Different dyes and onium salts were investigated. The action mechanism of the different photoinitiators systems is discussed.

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8

Righi, Helouise, Ana Rosa Costa, Dayane Carvalho Ramos Salles de Oliveira, Gabriel Flores Abuna, Mario Alexandre Coelho Sinhoreti, and Fabiana Scarparo Naufel. "Influence of Photoinitiator on Accelerated Artificial Aging and Bond Strength of Experimental Resin Cements." Brazilian Dental Journal 29, no. 1 (February 2018): 82–87. http://dx.doi.org/10.1590/0103-6440201801591.

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Abstract The goal of this study was to evaluate in vitro the effect of the photoinitiator phenylpropanedione (PPD), alone or combined with camphorquinone (CQ), on color stability of photoactivated resin cements and their bond strength to ceramics using a micro-shear test. Four resin cements were used: a commercial brand cement (RelyX Veneer®) and 3 experimental cements with different types and concentration of photoinitiators. For color analysis, ceramic discs were cemented on bovine dentin specimens to simulate indirect restorations (n=8) and were exposed to UV for 120 h and tested for color alteration using a reflectance spectrophotometer and the CIEL*a*b* system. Data were analyzed by Anova and Tukey’s test at 5% significance level. The color test results did not present statistically significant difference for the ∆E for all the studied cements, neither for ∆L, ∆a and ∆b. For the bond strength, all the studied cements showed statistically significant differences to each other, with the highest result for the RelyX Veneer® (29.07 MPa) cement, followed by the cement with CQ (21.74 MPa) and CQ+PPD (19.09 MPa) cement; the lowest result was obtained by the cement using only PPD as a photoinitiator (13.99 MPa). So, based on the studied parameters, PPD was not advantageous as photoinitiator of resin cements, because it showed a low value of bond strength to the ceramics and no superior color stability.

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9

Venter, Sandro Aurélio de Souza, Gedalias Custódio Martim, Andressa Dos Santos, Tiago Roerto Detomini, Eduardo Radovanovic, and Emerson Marcelo Girotto. "Effect of the photoinitiator system on the properties of a dental material based on a hybrid polymer." Brazilian Dental Science 19, no. 1 (March 14, 2016): 96. http://dx.doi.org/10.14295/bds.2016.v19i1.1233.

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Objective: In this study, the effects of two different cure protocols upon the properties of composites using a hybrid-polymer as dental resin were evaluated. Material and Methods: Two distinct dental composites were prepared, one containing a mixture of TEGDMA/bis-GMA (50:50) and, another containing a mixture of TEGDMA/p-MEMO (50:50), [p-MEMO: oligomeric inorganic precursor]. Both composites were polymerized with lucirin and canphorquinone as photoinitiators. The composites were made with a 70 % wt of inorganic filler. Flexural strength was evaluated with a universal test machine and the degree of conversion was measured by infrared spectroscopy. A helium pycnometer was used to obtain polymer shrinkage data. Sorption tests were performed and SEM microscopy was used to show deleterious effects upon the resins’ surfaces. Results: The sample base on TEGDMA/p-MEMO polymerized with lucirin (L-T/p) showed the best values of the monitored properties. Conclusion: Lucirin is the most suitable photoinitiator for dental composites containing hybrid polymers.KeywordsDental resins; Flexural strength; Hybrid polymer; Photoinitiator system; Polymerization shrinkage.

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10

Bertolo, Marcus Vinicius Loureiro, Rita de Cássia Martins Moraes, Carmem Pfeifer, Vinícius Esteves Salgado, Ana Rosa Costa Correr, and Luis Felipe J. Schneider. "Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites." Brazilian Dental Journal 28, no. 1 (February 2017): 35–39. http://dx.doi.org/10.1590/0103-6440201700841.

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Abstract The aim of this study was to determine the influence of photoinitiator systems on physical-chemical properties of flowable composites. Conventional (CFC), composed by bisphenol-glycidyl dimethacrylate (BisGMA)+triethyleneglycol dimethacrylate (TEGDMA), and self-adhesive (SAFC), composed by BisGMA+TEDGMA+bis{2-(methacryloyloxy) ethyl} phosphate (2MP), flowable composites were developed. Five photoinitiator systems were tested: camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), CQ+EDMAB+TPO and CQ+EDMAB+BAPO. A two-peak LED was used; degree of conversion (DC) and the maximum polymerization rate (RPmax) were determined by near infrared spectroscopy. For the yellowing degree a spectrophotometer was used. Water sorption (Wsp) was obtained after 30 days of water storage (n=5). Data were submitted to two-way analysis of variance and Tukey’s test (a=0.05). BAPO presented the highest DC and RPmax values for both series. SAFCs presented lower DC and RPmax for CQ+EDMAB-based materials. Greater yellowing was observed for SAFCs compared with CFCs, except for BAPO. Greater Wsp was observed for SAFCs compared with CFCs. The photoinitiator did not influence Wsp for CFCs, but TPO and BAPO presented the highest Wsp in SAFCs. The photoinitiator system affected differently the physical-chemical properties of CFCs and SAFCs.

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Zhu, Yifan, Emira Ramadani, and Eilaf Egap. "Thiol ligand capped quantum dot as an efficient and oxygen tolerance photoinitiator for aqueous phase radical polymerization and 3D printing under visible light." Polymer Chemistry 12, no. 35 (2021): 5106–16. http://dx.doi.org/10.1039/d1py00705j.

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We report here a rapid visible-light-induced radical polymerization in aqueous media photoinitiated by only ppm level thiol ligand capped cadmium selenide quantum dots. The photoinitiation system could be readily employed for photo 3D printing.

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12

Hola, Emilia, Maciej Pilch, and Joanna Ortyl. "Thioxanthone Derivatives as a New Class of Organic Photocatalysts for Photopolymerisation Processes and the 3D Printing of Photocurable Resins under Visible Light." Catalysts 10, no. 8 (August 8, 2020): 903. http://dx.doi.org/10.3390/catal10080903.

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In the present paper, novel thioxanthone-based compounds were synthesised and evaluated as a component of photoredox catalysts/photoinitiating systems for the free-radical polymerisation (FRP) of acrylates and the ring-opening cationic polymerisation (CP) of epoxy monomers. The performance of the obtained thioxanthones in two- and three-component photoinitiating systems, in combination with amines, iodonium or sulphonium salt, as well as with alkyl halide, for photopolymerisation processes upon exposure to light emitting diodes (LEDs) with a maximum emission of 405 nm and 420 nm, was investigated. The studied compounds act also as one-component free-radical photoinitiators. Fourier transform real-time infrared spectroscopy was used to monitor the kinetics of disappearance of the functional groups of the monomers during photoinitiated polymerisation. Excellent photoinitiating efficiency and high final conversions of functional groups were observed. Moreover, the influence of thioxanthone skeleton substitution on photoinitiating efficiency was discussed. The photochemical mechanism was also investigated through cyclic voltammetry. It was discovered that thioxanthone derivatives can be used as a metal-free photoredox catalyst active for both oxidative and reductive cycles. Furthermore, a photopolymerizable system based on novel thioxanthone derivatives in a stereolithography three-dimensional (3D) printing technology under visible sources of light was used. The effects of photoinitiator type system and monomer type in photoresins during 3D printing processes were explored. The outcome of this research is the development of high-performance visible photosensitive resins with improved photosensitivity obtained thanks to the development of entirely novel photoinitiating systems specifically adapted for this application.

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13

Huang, Yi, Guangdong Sun, Yating Ji, Dapeng Li, Qinguo Fan, and Jianzhong Shao. "Optimization and evaluation of a blue light photoinitiating system for textile inkjet printing." Textile Research Journal 89, no. 10 (June 22, 2018): 1964–74. http://dx.doi.org/10.1177/0040517518783346.

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A blue light curing process was developed to solve the nozzle clogging challenge commonly encountered in conventional textile pigment printing, by using camphorquinone (CQ) and ethyl-4-dimethylaminobenzoate (EDMAB) as a photoinitiator combination and substituting oligomers and monomers for a polymeric binder. High light absorption efficiency was insured by closely matching the spectrum of the photoinitiator with a custom-made blue light light-emitting diode set-up. Kinetic analyses of such a CQ/EDMAB system indicated that the maximum polymerization rate of the monomer was proportional to [PI]0.5 and [I0]0.5, while excessive high photoinitiator concentration (>1 wt%) will decrease the polymerization rate because of the “filter effect.” With optimized blue light curable pigment ink formula and irradiation conditions, the photocurable pigment printed fabrics exhibited uniform and vibrant colors, clear outlines, and excellent wet and dry rubbing fastness of grades 4 and 4–5, respectively.

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14

Lee, Jim H., Robert K. Prud'homme, and Ilhan A. Aksay. "Cure depth in photopolymerization: Experiments and theory." Journal of Materials Research 16, no. 12 (December 2001): 3536–44. http://dx.doi.org/10.1557/jmr.2001.0485.

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The depth of photocuring for a model resin system was investigated as a function of photoinitiator concentration. Direct measurements of gel thickness were made from thin films of cross-linked multifunctional methacrylate monomer. The monomer, 2,2-bis{4-[2-hydroxy-3-(methacryloxy)propoxy]phenyl}propane, was polymerized in a solution of trichloroethylene with an ultraviolet laser light source at 325 nm. The monomer solutions were photocured using varying levels of both photonic energy and photoinitiator concentration. An optimal photoinitiator concentration that maximized the gel cure depth was observed. Additionally, two regimes were shown to exist in which the shrinkage (upon solvent removal) was minimized or maximized. A model was developed to probe the physics of the system. Good agreement with experiment was obtained, and the model may be employed to predict both the existence and location of the optimal photoinitiator concentration and the corresponding cure depth. The study showed that photoinitiator plays a significant role in controlling the quality and performance of the formed gel network, with special regard to thickness of cured layers. This has potential application to fields as diverse as industrially cured coatings and dental fillings, and more generally, 3-dimensional rapid prototyping techniques.

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15

TOBA, Yasumasa. "Design of Photoinitiator System with Onium Berates." KOBUNSHI RONBUNSHU 59, no. 8 (2002): 449–59. http://dx.doi.org/10.1295/koron.59.449.

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Barcelos, L. M., M. G. Borges, C. J. Soares, M. S. Menezes, A. P. P. Fugolin, A. Dobson, V. Huynh, and C. S. Pfeifer. "Effect of photoinitiator system on polymerization of methacrylamides." Dental Materials 34 (2018): e136. http://dx.doi.org/10.1016/j.dental.2018.08.279.

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17

Ayub, Nur Farizah, Shahrir Hashim, Jamarosliza Jamaluddin, and Nadia Adrus. "New UV LED curing approach for polyacrylamide and poly(N-isopropylacrylamide) hydrogels." New Journal of Chemistry 41, no. 13 (2017): 5613–19. http://dx.doi.org/10.1039/c7nj00176b.

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18

Wang, Wan Hui, and Ji Hu. "Study on the UV Photosensitive of Hexaarylbiimidazole Photoinitiator System." Applied Mechanics and Materials 236-237 (November 2012): 771–74. http://dx.doi.org/10.4028/www.scientific.net/amm.236-237.771.

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2-chlorohexaarylbiimidazole; sensitizer; hydrogen donor; deeper layer’s curing speed Abstract.The ultraviolet photosensitive initiating system is composed of hexaarylbiimidazole (BCIM), sensitizer and hydrogen donor coinitiator. The effect of sensitizer and hydrogen donor on the curing speed, especially on the deeper layer’s curing speed of ink was studied. The experimental results shown that the deeper layer’s curing speed of the ink system mainly depend on the type and the amount of the sensitizer and the hydrogen donor. The amount of the total initiators in the ink formulation is optimized. This hexaarylbiimidazole initiating system is promisingly useful in silk-screening ink and “green ink” for printing circuit board

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Lee, Suk Kyu, and D. C. Neckers. "Two-photon radical-photoinitiator system based on iodinated benzospiropyrans." Chemistry of Materials 3, no. 5 (September 1991): 858–64. http://dx.doi.org/10.1021/cm00017a022.

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Han, Samsook, and Muncheul Lee. "New photochemical approach to cellulose fabric and photoinitiator system." Journal of Applied Polymer Science 105, no. 2 (2007): 352–59. http://dx.doi.org/10.1002/app.26053.

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Arslan, Mustafa, Gorkem Yilmaz, and Yusuf Yagci. "Dibenzoyldiethylgermane as a visible light photo-reducing agent for CuAAC click reactions." Polymer Chemistry 6, no. 47 (2015): 8168–75. http://dx.doi.org/10.1039/c5py01465d.

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Xiao, Wang, Cheng Huang, Wen Sheng Wang, Guo Jun Liu, Chun Yan Wei, and Byung Gil Min. "Preparation and Properties of Ecological Colored Cellulose Material." Materials Science Forum 743-744 (January 2013): 573–77. http://dx.doi.org/10.4028/www.scientific.net/msf.743-744.573.

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Ecological colored cellulose material was prepared via UV initiated photografting of acrylic acid/cationic dye system in this study. The colored cellulose material was characterized using scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). The effects of monomer concentration, photoinitiator amount, dye amount, pH value, grafting time, heating temperature and grafting method on the coloration of cellulose material were discussed. The results showed that the optimum process was as follows: the monomer concentration of 50wt%, photoinitiator amount of 3o.w.m.%, grafting time of 4min, and heating temperature of 70.

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Shete, Abhishek U., Bassil M. El-Zaatari, Jonathan M. French, and Christopher J. Kloxin. "Blue-light activated rapid polymerization for defect-free bulk Cu(i)-catalyzed azide–alkyne cycloaddition (CuAAC) crosslinked networks." Chemical Communications 52, no. 69 (2016): 10574–77. http://dx.doi.org/10.1039/c6cc05095f.

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Bulk photo-CuAAC networks are rapidly polymerized under blue light using novel photoinitiator system avoiding azide decomposition, yielding glassy, transparent films with narrow glass transition region.

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24

Wang, Yu-Hsuan, and Peter Wan. "Ketoprofen as a photoinitiator for anionic polymerization." Photochemical & Photobiological Sciences 14, no. 6 (2015): 1120–26. http://dx.doi.org/10.1039/c4pp00454j.

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Lu, Wei Xing, Lin Ling Wu, Chun Yu Ma, and Qian Feng Zhang. "Free Radical-Cationic Hybrid System Passivation Film for the Surface of Hot-Dip Aluminum-Zinc Coated Steel Plate." Key Engineering Materials 915 (March 29, 2022): 43–52. http://dx.doi.org/10.4028/p-d18ir5.

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3-Ethyl-3-benzoxy-methyl oxacyclobutane (TCM 104) and 3,4-epoxy-cyclohexyl carboxylic acid-3',4'-epoxy-cyclohexyl methyl ester (UVR 6110) as active diluents, a mixture of modified epoxy-acrylate and modified polyester acrylate in a certain proportion of oligomer, triaryl sulfonium hexafluorophosphate as cationic photoinitiator, irgacure 184 as free radical photoinitiator, and high-pressure mercury lamp as radiation source, and then the compound formula of free radical and cation hybrid photo-curing were prepared and further coated on the hot-dipped aluminum-zinc steel plate. After curing, the passivation film was characterized by neutral salt spray testing, FT-IR spectroscopy and electrochemical properties along with other relative evaluation criterions. The passivation film of this hybrid system can be cured at an energy of 600 mJ/cm2, and its performances are comparable to those of current water-based passivators.

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Cook, Wayne D., and Fei Chen. "Enhanced visible radiation photopolymerization of dimethacrylates with the three component thioxanthone (CPTXO)–amine–iodonium salt system." Polymer Chemistry 6, no. 8 (2015): 1325–38. http://dx.doi.org/10.1039/c4py01561d.

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The three component thioxanthone/iodonium/amine visible light photoinitiator system is four times more efficient due to irreversible oxidation of the ketyl and the amine radicals by the iodonium salt and the regeneration of the thioxanthone and produce twice as many active radicals.

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Li, Lihua, Han Yan, Henglin Xiao, Wentao Li, and Zhangshuai Geng. "Sand- and Clay-Photocured-Geomembrane Interface Shear Characteristics Using Direct Shear Test." Sustainability 13, no. 15 (July 22, 2021): 8201. http://dx.doi.org/10.3390/su13158201.

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It is well known that geomembranes frequently and easily fail at the seams, which has been a ubiquitous problem in various applications. To avoid the failure of geomembrane at the seams, photocuring was carried out with 1~5% photoinitiator and 2% carbon black powder. This geomembrane can be sprayed and cured on the soil surface. The obtained geomembrane was then used as a barrier, separator, or reinforcement. In this study, the direct shear tests were carried out with the aim to investigate the interfacial characteristics of photocured geomembrane–clay/sand. The results show that a 2% photoinitiator has a significant effect on the impermeable layer for the photocured geomembrane–clay interface. As for the photocured geomembrane–sand interface, it is reasonable to choose a geomembrane made from a 4% photoinitiator at the boundary of the drainage layer and the impermeable layer in the landfill. In the cover system, it is reasonable to choose a 5% photoinitiator geomembrane. Moreover, as for the interface between the photocurable geomembrane and clay/sand, the friction coefficient increases initially and decreases afterward with the increase of normal stress. Furthermore, the friction angle of the interface between photocurable geomembrane and sand is larger than that of the photocurable geomembrane–clay interface. In other words, the interface between photocurable geomembrane and sand has better shear and tensile crack resistance.

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dell’Erba, Ignacio E., Gustavo F. Arenas, Walter F. Schroeder, Silvana V. Asmussen, and Claudia I. Vallo. "Hybrid organic–inorganic macromolecular photoinitiator system for visible-light photopolymerization." Progress in Organic Coatings 77, no. 11 (November 2014): 1848–53. http://dx.doi.org/10.1016/j.porgcoat.2014.06.010.

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29

Bouchikhi, Nouria, Manel Bouazza, Salah Hamri, Ulrich Maschke, Djahida Lerari, Faycal Dergal, Khaldoun Bachari, and Lamia Bedjaoui-Alachaher. "Photo-curing kinetics of hydroxyethyl acrylate (HEA): synergetic effect of dye/amine photoinitiator systems." International Journal of Industrial Chemistry 11, no. 1 (December 17, 2019): 1–9. http://dx.doi.org/10.1007/s40090-019-00197-7.

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AbstractThe aim of this study is to examine and evaluate several dye/amine systems as photoinitiators for photopolymerization of 2-hydroxyethyl acrylate (HEA) monomer under visible light conditions. For this purpose, a series of dye/amine photoinitiators were formed using methylene blue (MB) or acridine orange (AO) as photosensitizers, and triethanolamine (TEOA), ethyl 4-(dimethylamino) benzoate (EDMAB), trioctylamine (TOA), and N,N-diméthylallylamine (DMAA) as co-initiators. The photopolymerization kinetic of the HEA monomer in the presence of proposed dye/amine systems was performed using Fourier-transform infrared spectroscopy (FTIR) analysis and the synergetic effect of the dye/amine photoinitiators systems on the photopolymerization efficiency was examined. Interestingly, (MB/EDMAB) system shows the better reactivity with a total conversion of HEA monomer.

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30

Balcerak, Alicja, Janina Kabatc, Zbigniew Czech, Małgorzata Nowak, and Karolina Mozelewska. "High-Performance UV-Vis Light Induces Radical Photopolymerization Using Novel 2-Aminobenzothiazole-Based Photosensitizers." Materials 14, no. 24 (December 17, 2021): 7814. http://dx.doi.org/10.3390/ma14247814.

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The popularity of using the photopolymerization reactions in various areas of science and technique is constantly gaining importance. Light-induced photopolymerization is the basic process for the production of various polymeric materials. The key role in the polymerization reaction is the photoinitiator. The huge demand for radical and cationic initiators results from the dynamic development of the medical sector, and the optoelectronic, paints, coatings, varnishes and adhesives industries. For this reason, we dealt with the subject of designing new, highly-efficient radical photoinitiators. This paper describes novel photoinitiating systems operating in UV-Vis light for radical polymerization of acrylates. The proposed photoinitiators are composed of squaraine (SQ) as a light absorber and various diphenyliodonium (Iod) salts as co-initiators. The kinetic parameters of radical polymerization of trimethylolpropane triacrylate (TMPTA), such as the degree of double bonds conversion (C%), the rate of photopolymerization (Rp), as well as the photoinitiation index (Ip) were calculated. It was found that 2-aminobenzothiazole derivatives in the presence of iodonium salts effectively initiated the polymerization of TMPTA. The rates of polymerization were at about 2 × 10−2 s−1 and the degree of conversion of acrylate groups from 10% to 36% were observed. The values of the photoinitiating indexes for the most optimal initiator concentration, i.e., 5 × 10−3 M were in the range from 1 × 10−3 s−2 even to above 9 × 10−3 s−2. The photoinitiating efficiency of new radical initiators depends on the concentration and chemical structure of used photoinitiator. The role of squaraine-based photoinitiating systems as effective dyeing photoinitiators for radical polymerization is highlighted in this article.

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31

Ayub, Nur Farizah, Shahrir Hashim, and Nadia Adrus. "Development of UV LED Hydrogel Formulation Based on Polyacrylamide Hydrogel." Applied Mechanics and Materials 695 (November 2014): 102–5. http://dx.doi.org/10.4028/www.scientific.net/amm.695.102.

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Recent trends show that the UV LED light source can greatly reduce environmental effect without compromising performance as compared to conventional UV mercury-based lamp (UV Hg) system. In this study, the possibility of using UV LED technology for photopolymerization of polyacrylamide (PAAm) hydrogels is presented. This has strongly drives the needs for suitable water-soluble photoinitiator formulation. Specifically, the photoinitiator must possess characteristic wavelength within UV LED range as UV LED emits monochromatic light sources only (365 nm or 385 nm). Here, the commercially available photoinitiator Oligo [2-hydroxy-2-methyl-1-[4-(1-methylvinyl) phenyl] propanone] (Chivacure 300) was chosen. However, Chivacure 300 has limited solubility in water. Hence, addition of tetrahydrofuran (THF) at various ratios was required. The results demonstrated that 9.5:0.5 ratio of water/THF was the minimum ratio needed for the solubility of Chivacure 300. After the synthesis of PAAm hydrogels, almost complete conversion of hydrogels was achieved (> 80 %). The highest conversion was achieved with formulation of Chivacure 300 in 9.5:0.5 ratio of water/THF. At this ratio, the hydrogels obtained were transparent. With increasing ratio of THF in water, the appearance of hydrogels gradually changed to cloudy. Indeed, UV LED technology can be used to polymerize PAAm hydrogels with comparably high conversion to conventional UV Hg system.

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32

Chen, Yu, Guanglei Li, Junru Han, and Tao Wang. "A new visible light bimolecular photoinitiator system for free radical polymerization." Journal of Photochemistry and Photobiology A: Chemistry 222, no. 2-3 (August 2011): 330–35. http://dx.doi.org/10.1016/j.jphotochem.2011.07.005.

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33

Yasuike, Madoka, Motoyuki Shima, Ken'ichi Koseki, Tsuguo Yamaoka, Masako Sakuragi, Masako Sakuragi, and Kunihiro Ichimura. "Triplet state electron transfer pathway for tetrabenzoporphyrin-diphenyliodonium salt photoinitiator system." Journal of Photochemistry and Photobiology A: Chemistry 64, no. 1 (March 1992): 115–22. http://dx.doi.org/10.1016/1010-6030(92)85098-f.

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34

Liu Yuyan, Jing Xianghai, Ren Zhong, and Du Xingwen. "The Cure Kinetics of Sulfonium Salt UV Cationic Photoinitiator/Epoxy System." Journal of Reinforced Plastics and Composites 28, no. 4 (June 27, 2008): 499–507. http://dx.doi.org/10.1177/0731684407086591.

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35

Ichimura, Kunihiro, and Masako Sakuragi. "A spiropyran-iodonium salt system as a two photon radical photoinitiator." Journal of Polymer Science: Polymer Letters Edition 26, no. 4 (April 1988): 185–89. http://dx.doi.org/10.1002/pol.1988.140260403.

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36

LEE, S. K., and D. C. NECKERS. "ChemInform Abstract: Two-Photon Radical-Photoinitiator System Based on Iodinated Benzospiropyrans." ChemInform 23, no. 3 (August 22, 2010): no. http://dx.doi.org/10.1002/chin.199203112.

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37

Sun, Ke, Xiaotong Peng, Zengkang Gan, Wei Chen, Xiaolin Li, Tao Gong, and Pu Xiao. "3D Printing/Vat Photopolymerization of Photopolymers Activated by Novel Organic Dyes as Photoinitiators." Catalysts 12, no. 10 (October 19, 2022): 1272. http://dx.doi.org/10.3390/catal12101272.

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Even though numerous organic dyes which are used as photoinitiators/photocatalysts during photopolymerization have been systematically investigated and collected in previous reviews, further designs of these chromophores and the developments in high-performance photoinitiating systems have emerged in recent years, which play the crucial role in 3D printing/Vat polymerization. Here, in this mini-review, various families of organic dyes that are used as newly synthesized photoinitiators/photocatalysts which were reported in literature during 2021–2022 are specified by their photoinitiation mechanisms, which dominate their performance during photopolymerization, especially in 3D printing. Markedly, visible light-induced polymerization could be employed in circumstances not only upon the irradiation of artificial light sources, e.g., in LEDs, but also in sunlight irradiation. Furthermore, a short overview of the achievements of newly developed mechanisms, e.g., RAFT, photoinitiator-RAFT, and aqueous RAFT using organic chromophores as light-harvesting compounds to induce photopolymerization upon visible light irradiation are also thoroughly discussed. Finally, the reports on the semiconducting nanomaterials that have been used as photoinitiators/photocatalysts during photopolymerization are also introduced as perspectives that are able to expand the scope of 3D printing and materials science due to their various advantages such as high extinction coefficients, broad absorption spectra, and having multiple molecular binding points.

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38

Lago, Miguel A., Raquel Sendón, Juana Bustos, María T. Nieto, Perfecto Paseiro Losada, and Ana Rodríguez-Bernaldo de Quirós. "Migration Studies of Two Common Components of UV-curing Inks into Food Simulants." Molecules 24, no. 19 (October 7, 2019): 3607. http://dx.doi.org/10.3390/molecules24193607.

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The Rapid Alert System for Food and Feed (RASFF) has reported many cases of different UV curing inks components in foodstuffs during the last few years. These contaminants reach foodstuffs mainly by set-off, their principal migration mechanism from the package. Under this premise, this work has tried to characterize the process of migration of two common UV ink components: a photoinitiator (4-Methylbenzophenone) and a coinitiator (Ethyl-4-(dimethylamino) benzoate), from the most common plastic material used in food packaging low-density polyethylene (LDPE) into six different food simulants. The migration kinetics tests were performed at four different common storage temperatures, obtaining the key migration parameters for both molecules: the coefficients of diffusion and partition. The migration process was highly dependent on the storage conditions, the photoinitiator properties and the pH of the foodstuff.

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39

Dumur, Frédéric. "Recent Advances on Visible Light Metal-Based Photocatalysts for Polymerization under Low Light Intensity." Catalysts 9, no. 9 (August 30, 2019): 736. http://dx.doi.org/10.3390/catal9090736.

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In recent years, polymerization processes activated by light have attracted a great deal of interest due to the wide range of applications in which this polymerization technique is involved. Parallel to the traditional industrial applications ranging from inks, adhesives, and coatings, the development of high-tech applications such as nanotechnology and 3D-printing have given a revival of interest to this polymerization technique known for decades. To initiate a photochemical polymerization, the key element is the molecule capable to interact with light, i.e., the photoinitiator and more generally the photoinitiating system, as a combination of several components is often required to create the reactive species responsible for the polymerization process. With the aim of reducing the photoinitiator content while optimizing the polymerization yield and/or the polymerization speed, photocatalytic systems have been developed, enabling the photosensitizer to be regenerated during the polymerization process. In this review, an overview of the photocatalytic systems developed for polymerizations carried out under a low light intensity and visible light is provided. Over the years, a wide range of organometallic photocatalysts has been proposed, addressing both the polymerization efficiency and/or the toxicity, as well as environmental issues.

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40

Kojima, Kyoko, Masato Ito, Hajime Morishita, and Nobuaki Hayashi. "A Novel Water-Soluble Photoinitiator for the Acrylic Photopolymerization Type Resist System." Chemistry of Materials 10, no. 11 (November 1998): 3429–33. http://dx.doi.org/10.1021/cm9801688.

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41

Seretoudi, Georgia, and Irini Sideridou. "Benzil/N,N-Dimethylaminoethyl Methacrylate System as Photoinitiator for Methyl Methacrylate Polymerization." Journal of Macromolecular Science, Part A 32, no. 6 (June 1995): 1183–95. http://dx.doi.org/10.1080/10601329508011034.

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42

Delgado, AJ, EM Castellanos, MAC Sinhoreti, DC Oliveira, N. Abdulhameed, S. Geraldeli, TA Sulaiman, and J.-F. Roulet. "The Use of Different Photoinitiator Systems in Photopolymerizing Resin Cements Through Ceramic Veneers." Operative Dentistry 44, no. 4 (July 1, 2019): 396–404. http://dx.doi.org/10.2341/17-263-l.

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SUMMARY Objective: To evaluate the effect of different photoinitiator systems on photopolymerizing resin cements through ceramic veneers with different thickness on microshear bond strength (μSBS), flexural strength (FS), and ultimate tensile strength (UTS) and verify the light attenuation through these ceramic veneers. Methods and Materials: Four photopolymerizing experimental resin cements were produced with the same resin matrix and associated with four different photoinitiator systems: camphorquinone (CQ), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), Ivocerin, and TPO + Ivocerin. Eighty disc-shaped ceramic veneers (IPS Empress Esthetic, Ivoclar Vivadent) were fabricated (10-mm diameter) in two different thicknesses: 0.7 and 1.5 mm. A previously characterized multiwave LED (Bluephase G2, Ivoclar Vivadent) was standardized for 40 seconds of photoactivation. Light transmittance through each ceramic veneer thickness (n=5) was measured using a spectrometer (USB 2000, Ocean Optics). The μSBS of each resin cement (n=15) to the ceramic veneer was evaluated using 0.5-mm cylinders with 0.7-mm diameters photoactivated through the different ceramic veneer thicknesses. Samples for FS and UTS tests were made either with or without ceramics veneers (0.7 and 1.5 mm) fixed to the light-curing tip. Data were submitted to two-way analysis of variance and the Tukey test (α=0.05). Results: The multiwave LED emitted higher irradiance into the blue wavelength spectra than into the violet wavelength spectra (p=0.0001). Light transmittance through the ceramic veneers was reduced in a systematic manner based on thickness regardless of the wavelength spectra emitted from the multiwave LED (p=0.00037). The μSBS was reduced in a systematic manner based on thickness regardless of the photoinitiator system (p<0.05). However, resin cements with CQ and Ivocerin showed higher bond strength values in comparison to the resin cement with TPO regardless of the ceramic veneer thickness (p<0.05). The FS and UTS means decreased (p<0.05) with the interposition of 0.7- and 1.5-mm ceramic veneers for all resin cements. The resin cement containing only TPO showed the lowest FS and UTS means (p<0.05) for all ceramic veneers. Conclusions: The thickness of the ceramic veneers reduced the irradiance of the multiwave LED in all wavelength spectra. Ivocerin alone or associated with TPO showed to be an effective alternative photoinitiator to substitute for CQ. The resin cement containing only TPO had lower bond strength values in comparison to resin cements with CQ, Ivocerin, and Ivocerin + TPO.

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Liao, Feng, and Xing Rong Zeng. "Preparation and Properties of UV Curable Silica Coatings from MPTMS and TEOS." Advanced Materials Research 181-182 (January 2011): 611–16. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.611.

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UV curable 3-(trimethoxysilyl) propyl methacrylate MPTMS modified silica hybrid coating was prepared through sol-gel process from TEOS and MPTMS in acid medium for different ratios between TEOS and MPTMS. The structure of the hybrid coating and the formation of inorganic-organic hybrid networks were studied by FT-IR. It was found that the organic networks were formed by the polymerization of C=C bonds at 1638 cm-1. The influences of the photoinitiator content and the curing time on the curing degree of the mixture system were investigated. The results showed that the optimal photoinitiator content was 3%, and curing time was 180 s. The thermal stability of the UV cured coating was investigated by TG-DTA. The results showed that the contents of low-molecular compounds such as H2O, CH3OH, etc. were decreased in cured coatings with the increasing of the MPTMS concentration, thus significantly decreasing of the thermal weight-loss at temperature lower than 400°C.

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44

Abadie, Marc J. M., and Vanda Yu Voytekunas. "New Trends in UV Curing." Eurasian Chemico-Technological Journal 6, no. 1 (April 7, 2016): 67. http://dx.doi.org/10.18321/ectj336.

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We present an overview of the use of photochemistry applied to polymerization and crosslinking reactions by radical or cationic process used for thin film technologies and more generally for coatings. Industrially, most of the formulations used are initiated by radical mechanism. Since the discovery by J. Crivello of iodonium and sulfonium salts, the market has been oriented to use cationic systems to crosslink monomers/oligomers. One of the main advantage of such a system is that it is not sensitive to the presence of oxygene as it is for radical mechanisms. An overview of a photosensitive formulation is presented i.e. photoinitiators, photosensitisers, monomers and/or oligomers mainly used by formulators and additives. A new technique which has been developed to study and optimise any photosensitive formulation – differential phto calorimetry DPC – and which permits to determine kinetic parameters such as enthalpy, degree of conversion, rate constant, Arrhenius parameters, etc. is also describe. Some of the main characteristics and properties of UV cured polymers like acrylates, epoxides, vinylethers and others are correlated with their structures and the photocuring conditions. Applications to thin film technologies based on acrylates, epoxides and silicones is presented. A promising area of research which opens a new route for the obtention of new structure of alternating copolymers for coatings without the use of photoinitiator and based on charge transfer complex CTC is also presented.

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45

Chu, Fu Qiang, Yu Xin Liu, and Chang Li Xu. "Study on the Combination Mechanism of the Water-Based UV Curable Ink and Paper." Applied Mechanics and Materials 731 (January 2015): 488–91. http://dx.doi.org/10.4028/www.scientific.net/amm.731.488.

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The bonding mechanism between water-based UV curable ink and active groups on paper’s fiber during curing process was studied in this paper. Low viscosity water-based UV-cured resin was synthesized by epoxy resins, epoxy diluent, acrylic acid and maleic anhydride in the presence of catalyst. The viscosity of the synthesis system and synthetic products were significantly reduced when epoxy diluent was added to replace parts of the epoxy resin. Epoxy diluent was very useful in reducing the viscosity of the product, but over-dose would have negative effects on the quality of the cured film. The water-based epoxy acrylate prepolymer was used as the substitution for the ink to investigate the binding mechanism between the active groups of prepolymer and fiber under UV irradiation. The prepolymer and photoinitiator were mixed and the mixture was diluted to an appropriate viscosity by a small amount of water, then printed on the paper by the method of analog printing and curred by UV curing machine. The printed paper was used to extract lignin by enzymatic/mild acidolysis. FT-IR was used to characterize the changes of the active groups in lignin. The results showed that the changes of active groups in lignin were founded in the existence of ultraviolet and photoinitiator, which consistent with the change of double bonds in prepolymer. The free radicals produced by photoinitiator in curing process not only promoted the double bonds to polymerize, but also accelerated the active groups of lignin binding. Experiments show that chemical bonds exist between them.

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46

Crivello, James V. "A new visible light sensitive photoinitiator system for the cationic polymerization of epoxides." Journal of Polymer Science Part A: Polymer Chemistry 47, no. 3 (December 18, 2008): 866–75. http://dx.doi.org/10.1002/pola.23203.

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47

Bartkowiak, Marcin, Zbigniew Czech, Hyun-Joong Kim, Gyu-Seong Shim, Małgorzata Nowak, and Adrian Krzysztof Antosik. "Photoreactive UV-Crosslinkable Acrylic Pressure-Sensitive Adhesives (PSA) Containing Multifunctional Photoinitiators." Polymers 13, no. 24 (December 16, 2021): 4413. http://dx.doi.org/10.3390/polym13244413.

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The use of ultraviolet radiation (UV) technology for the crosslinking of acrylic pressure-sensitive adhesives (PSA) is the one of various crosslinking methods, being the alternative to the conventional crosslinking process of solvent-based acrylic systems. It also requires a photoinitiator to absorb the impinging UV and induce photocrosslinking. As previously mentioned, a photoinitiator is one of the important and necessary components in UV-inducted crosslinking of acrylic pressure-sensitive adhesives. The activity of multifunctional conventional saturated photoinitiators of type I and type II, especially benzophenone-based in the photoreactive UV-crosslinkable acrylic PSA was described. The effect of the multifunctional type-II photoinitiators on the acrylic PSA, such as tack, peel adhesion and shear strength were summarized.

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48

Wang, Qing Shan, Yun Wang, Rui Li, Meng Meng Zhao, Ji Jun Sun, and Yan Gao. "Effects of Light-Initiation Agent on Mechanical Properties of Light-Cured Nano-Hydroxyapatite Composite for Dental Restoration." Applied Mechanics and Materials 138-139 (November 2011): 1012–16. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.1012.

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In order to improve the experimental evidence of hotoinitiator, the effects of various dose of photoinitiator on mechanical properties of nanohydroxyapatite composite were investigated. According to the light initiating system, CQ and DMAEMA accounted for 0.8wt％, 1.0wt％, 1.2wt％ of total resin matrix, respectively. And then NHA processed by KH-570 was mixed with resin matrix in the ratio of 55:45. Then three groups （A, B, and C） of light-cured nanohydroxyapatite composites were prepared. Karuisima composite resin was used as control group D. The cured depth, compressive strength, and flexural strength were determined in each group. The results showed that as the ratio of photoinitiator increased, the cured depth increased, while the mechanical function declined. In group B, there were no significant differences in compressive strength, and flexural strength as compared with control group,P>0.05. It is suggested that the quantity of CQ and DMAEMA in resin matrix were 1.0wt% respectively, the new light-cured nanohydroxyapatite composite has good qualities in both cured depth and mechanical property.

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49

Yang, Kai-Hung, Gabriella Lindberg, Bram Soliman, Khoon Lim, Tim Woodfield, and Roger J. Narayan. "Effect of Photoinitiator on Precursory Stability and Curing Depth of Thiol-Ene Clickable Gelatin." Polymers 13, no. 11 (June 5, 2021): 1877. http://dx.doi.org/10.3390/polym13111877.

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Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling ratio, mechanical properties, rheological properties, and curing depth were evaluated as a function of time with three photo-initiating systems: Irgacure 2959 (Ig2959; 320–500 nm), lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 320–500 nm), and ruthenium/sodium persulfate (Ru/SPS; 400–500 nm). Results demonstrated that GelAGE precursory solutions mixed with either Ig2959 or LAP remained stable over time while the Ru/SPS system enabled the onset of controllable redox polymerization without irradiation during pre-incubation. Photo-polymerization using the Ru/SPS system was significantly faster (<5 s) compared to both Ig2959 (70 s) and LAP (50 s). Plus, The Ru/SPS system was capable of polymerizing a thick construct (8.88 ± 0.94 mm), while Ig2959 (1.62 ± 0.49 mm) initiated hydrogels displayed poor penetration depth with LAP (7.38 ± 2.13 mm) in between. These results thus support the use of the visible light based Ru/SPS photo-initiator for constructs requiring rapid gelation and a good curing depth while Ig2959 or LAP can be applied for photo-polymerization of GelAGE materials requiring long-term incubation prior to application if UV is not a concern.

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50

Han, Win Tun, Taesik Jang, Shengyang Chen, Lydia Shi Hui Chong, Hyun-Do Jung, and Juha Song. "Improved cell viability for large-scale biofabrication with photo-crosslinkable hydrogel systems through a dual-photoinitiator approach." Biomaterials Science 8, no. 1 (2020): 450–61. http://dx.doi.org/10.1039/c9bm01347d.

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Through concurrent use of photoinitiators with different activation kinetics, a hydrogel crosslinking system exhibited efficient crosslinking properties and desired mechanical properties with high cell viability.

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