Dual roles for promoting monomers to polymers: A conjugated sulfonium salt photoacid generator as photoinitiator and photosensitizer in cationic photopolymerization

Jin, Ming; Wu, Xingyu; Malval, Jean Pierre; Wan, Decheng; Pu, Hongting

doi:10.1002/pola.28154

Cited by 29 publications

(38 citation statements)

References 39 publications

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“…Under irradiation of 300–500 nm LED light for 5 min, only one spin adduct was observed (a N =14.44 G and a H =2.40 G) for OEC3‐1/PBN system (Table S1). The values of the hyperfine coupling ( hfc ) constants suggest that after photodecarboxylation, the trapped radicals are phenyl radicals, as discussed in literature . Identical hfc values were observed for OEC4/PBN , and this confirms the same trapped phenyl radials via a similar photodecomposition mechanism.…”

Section: Methodssupporting

confidence: 78%

Cleavable Unimolecular Photoinitiators Based on Oxime‐Ester Chemistry for Two‐Photon Three‐Dimensional Printing

Qiu

Zhu

et al. 2019

ChemPhotoChem

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The development of efficient two-photon initiators (2PIs) is critical to promote two-photon three-dimensional (3D) printing for market applications. On the basis of the photocleavage concept, several unimolecular 2PIs that contain coumarin moieties (as two-photon absorption chromophores) and oximeester groups (as initiation functional groups) were synthesized. Under visible light irradiation, the investigated oxime-esters, sensitive to a broad wavelength range from 400 to 460 nm, undergo direct photocleavage followed by decarboxylation, forming active free radicals to effectively induce polymerization. Interestingly, the photoinitiators exhibit good photobleaching properties, which makes them applicable for photopolymerization of thick materials and dental restorative materials. In twophoton 3D printing tests with acrylate formulations, the oximeester derivatives were used to build complex 3D microstructures with submicrometer or even nanometer spatial resolution. The initiator comprised of a conjugated coumarin and an oxime ester attached at the 3-position exhibited a low threshold laser power required for polymerization and had a broad processing window similar to a highly efficient 2PI in the literature.

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Section: Methodssupporting

confidence: 78%

Cleavable Unimolecular Photoinitiators Based on Oxime‐Ester Chemistry for Two‐Photon Three‐Dimensional Printing

Qiu

Zhu

et al. 2019

ChemPhotoChem

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“…Such natural dyes exhibit great potential to act as nontoxic photoinitiators for the fabrication of biocompatible polymeric materials . After the absorption of suitable light, natural dyes are promoted to excited states and can then interact with additives through electron (or energy) transfer reactions to yield active species (e.g., cations or radicals) to initiate photopolymerization reactions . The relevant reactivity between natural dyes and additives is strongly related to their photochemical properties.…”

Section: Introductionmentioning

confidence: 99%

“…[11] After the absorption of suitable light, natural dyes are promoted to excited states and can then interact with additives through electron (or energy) transfer reactions to yield active species (e.g., cations or radicals) to initiate photopolymerization reactions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The relevant reactivity between natural dyes and additives is strongly related to their photochemical properties. Recently, curcumin (a yellow-orange natural dye derived from rhizomes of Curcuma longa)-based photo initiating systems have been reported to demonstrate excellent photoinitiation…”

Section: Introductionmentioning

confidence: 99%

Multihydroxy‐Anthraquinone Derivatives as Free Radical and Cationic Photoinitiators of Various Photopolymerizations under Green LED

Zhang

Hill

Lalevée

et al. 2018

Macromol. Rapid Commun.

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Multihydroxy-anthraquinone derivatives [i.e., 1,2,4-trihydroxyanthraquinone (124-THAQ), 1,2,7-trihydroxyanthraquinone (127-THAQ), and 1,2,5,8-tetrahydroxyanthraquinone (1258-THAQ)] can interact with various additives [e.g., iodonium salt, tertiary amine, N-vinylcarbazole, and 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine] under household green LED irradiation to generate active species (cations and radicals). The relevant photochemical mechanism is investigated using quantum chemistry, fluorescence, cyclic voltammetry, laser flash photolysis, steady state photolysis, and electron spin resonance spin-trapping techniques. Furthermore, the multihydroxy-anthraquinone derivative-based photoinitiating systems are capable of initiating cationic photopolymerization of epoxides or divinyl ethers under green LED, and the relevant photoinitiation ability is consistent with the photochemical reactivity (i.e., 124-THAQ-based photoinitiating system exhibits highest reactivity and photoinitiation ability). More interestingly, multihydroxy-anthraquinone derivative-based photoinitiating systems can initiate free radical crosslinking or controlled (i.e., reversible addition-fragmentation chain transfer) photopolymerization of methacrylates under green LED. It reveals that multihydroxy-anthraquinone derivatives can be used as versatile photoinitiators for various types of photopolymerization reactions.

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“…Now, the commercial PAGs exhibit weak spectral sensitivity at long wavelengths ( λ abs > 320 nm), which limit their applications of new light sources, for example, light‐emitting diodes (LEDs) . PAGs have been adapted to operate under LED irradiation, especially near‐UV/visible LEDs . These eco‐friendly light sources have the advantages of low cost, absence of harmful ultraviolet light, high efficiency, and so on …”

Section: Introductionmentioning

confidence: 99%

D‐π‐a‐type oxime sulfonate photoacid generators for cationic polymerization under UV–visible LED irradiation

Jin

Zhou

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Four D-p-A-type nonionic oxime sulfonate photoacid generators (PAGs) have been designed and synthesized for use in light-emitting diode (LED) excitable cationic photoinitiators, in which N,N-diphenylamino was used as electron donor with trifluoroacetophenone-based oxime sulfonates (trifluoromethanoesulfonate and p-toluenesulfonate) as electron acceptor and substituted fluorene and biphenyl groups as the p-conjugated systems. PAG-Ben-Tol (with biphenyl and p-toluenesulfonate) and PAG-Flu-Tol (with fluorene and p-toluenesulfonate) showed high quantum yields of photoacid generation (0.33-0.50) and very good thermal stability (over 250 8C). The absorbance spectra of these PAGs were consistent with the emission spectra of commercially gained UV-visible LED light sources.The potential of these PAGs for cationic photoinitiators was tested in two cationic monomer systems. These PAGs needed low light intensity and low concentration for photopolymerization with high conversions of monomer, for example, over 80%, gained at 3.0 mW cm 22 from 365 to 470 nm LEDs. The photochemical mechanisms of these PAGs are comprehensively investigated and discussed in detail.

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Dual roles for promoting monomers to polymers: A conjugated sulfonium salt photoacid generator as photoinitiator and photosensitizer in cationic photopolymerization

Cited by 29 publications

References 39 publications

Cleavable Unimolecular Photoinitiators Based on Oxime‐Ester Chemistry for Two‐Photon Three‐Dimensional Printing

Cleavable Unimolecular Photoinitiators Based on Oxime‐Ester Chemistry for Two‐Photon Three‐Dimensional Printing

Multihydroxy‐Anthraquinone Derivatives as Free Radical and Cationic Photoinitiators of Various Photopolymerizations under Green LED

D‐π‐a‐type oxime sulfonate photoacid generators for cationic polymerization under UV–visible LED irradiation

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