Radical photoinitiation with LEDs and applications in the 3D printing of composites

Zhang, Yijun; Xu, Yangyang; Simon‐Masseron, Angélique; Lalevée, Jacques

doi:10.1039/d0cs01411g

Cited by 118 publications

(110 citation statements)

References 135 publications

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“…Due to its advantages, photopolymerization is seen as a pro-ecological technique, especially if cheap light-emitting diodes (LEDs) are used as a source of radiation. Light-induced polymerization is perceived as a modern method of curing because it is most often used to cure thin-film materials such as coatings, adhesives, printing inks [ 5 , 6 , 7 , 8 ], and others, such as dental fillings, hydrogels, or 3D-printed items [ 9 , 10 , 11 ]. Most commonly, depending on the type of photocurable material (resin, monomer, photoinitiator) and thus the emerging active centers that initiate the polyreactions, the reaction proceeds according to a radical or cationic mechanism.…”

Section: Introductionmentioning

confidence: 99%

Novel Multifunctional Epoxy (Meth)acrylate Resins and Coatings Preparation via Cationic and Free-Radical Photopolymerization

et al. 2021

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In this work, a series of novel multifunctional epoxy (meth)acrylate resins based on a low-viscosity aliphatic triepoxide triglycidyl ether of trimethylolethane (TMETGE) and acrylic acid (AA) or methacrylic acid (MMA) have been synthesized. Thanks to the performed modification, the obtained prepolymers have both epoxides as well as carbon–carbon double bonds and differ in their amount. The obtained results indicate that the carboxyl-epoxide addition esterification occurs in the presence of a catalyst (triphenylphosphine) at a temperature of 90 °C, whilst the required degree of conversion can be achieved simply by varying both the reagents ratio and reaction time. The structure of synthesized copolymers was confirmed by spectroscopic analyses (FT-IR, 1H NMR, 13C NMR) and studied regarding its nonvolatile matter content (NV), acid value (PAVs), as well as its epoxy equivalent value (EE). Due to the presence of both epoxy and double carbon–carbon pendant groups, one can apply two distinct mechanisms: (i) cationic ring-opening polymerization or (ii) free-radical polymerization to crosslink polymer chains. Synthesized epoxy (meth)acrylate prepolymers were further employed to formulate photocurable coating compositions. Hence, when cationic photoinitiators were applied, polyether-type polymer chains with pending acrylate or methacrylate groups were formed. In the case of free-radical polymerization, epoxy (meth)acrylates certainly formed a poly(meth)acrylate backbone with pending epoxy groups. Further, photopolymerization behavior and properties of cured coatings were investigated regarding some structural factors and parameters. Moreover, reaction rate coefficients of photo-cross-linking by both cationic ring-opening and free-radical photopolymerization of the received epoxy (meth)acrylate resins were determined via real-time infrared spectroscopy (RT-IR). Lastly, basic physicomechanical properties, such as tack-free time, hardness, adhesion, gloss, and yellowness index of cured coatings, were evaluated.

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Section: Introductionmentioning

confidence: 99%

Novel Multifunctional Epoxy (Meth)acrylate Resins and Coatings Preparation via Cationic and Free-Radical Photopolymerization

et al. 2021

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“…Photopolymers can also suffer from limited mechanical properties; reinforcing fillers can thus be used [ 51 ], but their type and content have to be controlled based on the light absorption of the system [ 52 ].…”

Section: Limitations Of Photoprocesses and Potential Opportunities Of New Developmentsmentioning

confidence: 99%

Photoinduced Processes as a Way to Sustainable Polymers and Innovation in Polymeric Materials

Bongiovanni

Vacche

2021

Polymers

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Photoinduced processes have gained considerable attention in polymer science and have greatly implemented the technological developments of new products. Therefore, a large amount of research work is currently developed in this area: in this paper we illustrate the advantages of a chemistry driven by light, the present perspectives of the technology, and summarize some of our recent research works, honoring the memory of Prof. Aldo Priola who passed away in March 2021 and was one of the first scientists in Italy to contribute to the field.

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“…[ 1,2 ] This polymerization technique has been successfully applied in many fields including conventional industries (e.g., ink, adhesive) and many cutting‐edge technologies (e.g., 3D–4D printing, microelectronic processing, etc.). [ 3–7 ] Light‐emitting diodes (LEDs) demonstrate many distinct advantages over traditional UV irradiation sources such as security, low cost and longer emission wavelengths. In recent years, near‐UV and visible LEDs have been widely used in scientific research and industrial production.…”

Section: Introductionmentioning

confidence: 99%

“…3D-4D printing, microelectronic processing etc). [3][4][5][6][7] Light-emitting diodes (LEDs) demonstrate many distinct advantages over traditional UV irradiation sources such as security, low cost and longer emission wavelengths. In recent years, near UV and visible LEDs have been widely used in scientific research and industrial production.…”

mentioning

confidence: 99%

Nitro‐Carbazole Based Oxime Esters as Dual Photo/Thermal Initiators for 3D Printing and Composite Preparation

Liu

Graff

Xiao

et al. 2021

Macromol. Rapid Commun.

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A series of Type I photoinitiators (PIs) based on a nitrocarbazole scaffold are developed and examined for the first time as photoinitiators for visible light photopolymerization. Three oxime esters (OXE‐M, OXE‐V, OXE‐P) varying by the terminal groups (acetyl, acryloyl and benzoyl) attached via the oxime ester group are originally prepared. As a result of this, the three PIs exhibit excellent photoinitiation abilities in the presence of acrylate monomers upon LED@ 405 nm irradiation. Markedly, OXE‐M exhibits a better performance than the benchmark Type I phosphine‐oxide (diphenyl(2,4,6‐trimethylbenzoyl)phosphine oxide TPO). Chemical mechanisms supporting the polymerization process with these PIs are investigated by steady state photolysis, molecular orbital calculations and real‐time Fourier transformed infrared spectroscopy. After the cleavage of N─O bond and decarboxylation, free radicals are generated to initiate the free radical polymerization efficiently. Free radical photopolymerization of OXE‐M is applied in direct laser write and 3D printing. Interestingly, OXE‐M exhibits thermal initiation behaviors in monomers and can be used as dual photo and thermal initiators. The highly opaque feature of carbon fibers makes it difficult for light penetration, so dual photo/thermal curing are used here to prepare carbon fiber composites.

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Radical photoinitiation with LEDs and applications in the 3D printing of composites

Abstract: Radical initiation upon LED light irradiation is discussed herein as well as its application in additive manufacturing.

Cited by 118 publications

References 135 publications

Novel Multifunctional Epoxy (Meth)acrylate Resins and Coatings Preparation via Cationic and Free-Radical Photopolymerization

Novel Multifunctional Epoxy (Meth)acrylate Resins and Coatings Preparation via Cationic and Free-Radical Photopolymerization

Photoinduced Processes as a Way to Sustainable Polymers and Innovation in Polymeric Materials

Nitro‐Carbazole Based Oxime Esters as Dual Photo/Thermal Initiators for 3D Printing and Composite Preparation

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