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3-Hydroxyflavone and N-phenylglycine in High Performance Photoinitiating Systems for 3D Printing and Photocomposites Synthesis
摘要： In this work, we propose to use 3-hydroxyflavone as a versatile high performance visible light photoinitiator (PIs) in combination with an amino acid (N-phenylglycine) for the free radical polymerization (FRP) of methacrylates in thick samples or composites upon visible light exposure (Light-Emitting Diode LED@405 nm or LED@477 nm). The high originality of this approach is the use of safer compounds in photoinitiating systems (flavone derivative/amino acid). 3-Hydroxyflavone can also be used in three-component systems with an iodonium salt and an amine for the cationic polymerization of epoxides upon exposure to near UV light LED@385 nm. Also interestingly, a charge transfer complex CTC between N-phenylglycine NPG and iodonium salt gives also remarkable initiating performance for free radical polymerization of methacrylates upon mild light irradiation conditions (LED@405 nm). High polymerization initiating abilities are found and high final reactive function conversions are obtained. The use of the new proposed initiating systems as materials for laser write or 3D printing experiments was also especially carried out with the formation of printed green fluorescent photopolymers. This green fluorescence obtained with naturally occurring 3-hydroxyflavone compound can be ascribed to the excited state intramolecular proton transfer ESIPT character. A full picture of the included photochemical mechanisms is given. Remarkably, 3-hydroxyflavone is also very efficient for photocomposites synthesis with glass fibers (thick samples with good depth of cure) using UV or LED@395 nm conveyor.
关键词： 3D printing,Cationic polymerization,Light-Emitting Diodes (LEDs),Free radical polymerization,photoinitiators,composites
更新于2025-09-23 15:21:21
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Ketone derivatives as photoinitiators for both radical and cationic photopolymerizations under visible LED and application in 3D printing
摘要： Six ketones (abbreviated as ketones 1-6) varying by the substitution pattern of the central cyclohexanones and the choice of the peripheral groups (thiophene or furane) were synthesized and proposed as unprecedented visible light sensitive photoinitiators, in combination with an amine and an iodonium salt, for the free radical polymerization of acrylates upon LED irradiation at 405 nm. For the photopolymerization of acrylates carried out as thin samples in laminate, all these ketones showed high photoinitiating abilities. Conversely, when tested as photoinitiators for thick samples, compared to the other 4 ketones, ketone 3 and ketone 5 both based onpiperidin-4-one as the central core and comprising furanes as peripheral groups proved to be the most efficient photoinitiators. Notably, the highest final polymerization conversion of Ebecryl 40, a tetrafunctional polyether acrylate, could be obtained using these two photoinitiators. The high photoreactivity of ketone 3 was highlighted by the steady state photolysis experiments. Meanwhile, ketone 3 could also promote the cationic polymerization of epoxides upon LED irradiation at 405 nm, in the presence of an iodonium salt. Interestingly, some 3D patterns could also be fabricated by free radical polymerization of Ebecryl 40 while using the ketone 3-based photoinitiating system.
关键词： free radical polymerization,ketones,cyclohexanone,photolysis,3D printing,cationic polymerization,LED,photoinitiating system
更新于2025-09-23 15:21:01
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Bicarbazole-based oxalates as photoinitiating systems for photopolymerization under UV-Vis LEDs
摘要： Photoinitiators are critical to initiate chain reactions in photopolymerization. For such applications, the absorption of photoinitiator must be compatible with the emission of light sources and enables the fast manufacturing of three-dimensional network or structures. Light-emitting diode (LED) is a new kind of energy-saving and environmental protection light source, exhibiting a substantial response in the near UV and visible range to replace the traditional mercury lamp and other light sources in photopolymerization. Here, we introduce methyl oxalate into bicarbazole chromophore (BiCz). By variation of the single or double substituents in the BiCz, we demonstrate that the absorption spectra can be adjusted and redshift to visible range and show good absorption in the near UV and visible range (365–475 nm). We explore their photochemistry based on experimental results and theoretical calculations and the mechanism of photoreactions have been verified. The super photostability by themselves and good hydrogen abstraction ability from amine co-initiator make them as excellent near UV and visible light active photoinitiators. Critically, the photoinitiation of the free-radical polymerization of acrylate monomers with low content (0.1% concentration) upon LED irradiation at 365–475 nm, exhibits excellent application potential in light curing and other fields.
关键词： free-radical polymerization,high efficiency,photoinitiators,UV–visible LEDs
更新于2025-09-23 15:19:57
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Synthesis and characterization of TiO2 co-polymeric hydrogel
摘要： In this study, TiO2 doped acrylic acid-co-vinyl pyrrolidone (AA-co-VP) composite co-polymeric hydrogel was synthesized by free radical polymerization technique. Titanium dioxide (TiO2) were chosen because of its superior properties such as high activity, chemical stability, low cost, non-toxicity, and stability during irradiation. TiO2 doping were carried out by varying mass ratios as 0.05%, 0.5% and 1%. Conversion, cross-linking and swelling values of each hydrogel were calculated. According to swelling behavior, while TiO2 dope ratio increase, swelling value was also increased. Chemical, morphological and thermal properties of hydrogels were specified by using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDX), mapping and thermogravimetric analysis (TGA-DSC) techniques. TiO2 doping provides superior properties to co-polymeric hydrogel. Hydrogels have also characteristic properties of both acrylic acid and vinyl pyrrolidone.
关键词： SEM-EDX,hydrogel,TGA-DSC,free radical polymerization,acrylic acid-co-vinyl pyrrolidone,FTIR,TiO2,swelling behavior
更新于2025-09-09 09:28:46