Recent advances on carbazole-based photoinitiators of polymerization

Dumur, Frédéric

doi:10.1016/j.eurpolymj.2020.109503

Cited by 89 publications

(58 citation statements)

References 187 publications

(189 reference statements)

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“…In order to obtain excellent light absorption properties, electron-donating moiety and electron-accepting moiety can be connected to the carbazole core, in order to elaborate push-pull structure dyes [ 22 ]. Indeed, numerous carbazole derivatives as PIs show a good performance in photopolymerization [ 23 , 24 , 25 ]. Benzophenone (BP) is a commercial Type II PI, which can initiate the free radical photopolymerization, but only in the presence of co-initiators (e.g., amines) under UV irradiation.…”

Section: Introductionmentioning

confidence: 99%

Monocomponent Photoinitiators based on Benzophenone-Carbazole Structure for LED Photoinitiating Systems and Application on 3D Printing

et al. 2020

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In this article, different substituents (benzoyl, acetyl, styryl) are introduced onto the carbazole scaffold to obtain 8 novel carbazole derivatives. Interestingly, a benzoyl substituent, connected to a carbazole group, could form a benzophenone moiety, which composes a monocomponent Type II benzophenone-carbazole photoinitiator (PI). The synergetic effect of the benzophenone moiety and the amine in the carbazole moiety is expected to produce high performance photoinitiating systems (PISs) for the free radical photopolymerization (FRP). For different substituents, clear effects on the light absorption properties are demonstrated using UV-Visible absorption spectroscopy. Benzophenone-carbazole PIs can initiate the FRP of acrylates alone (monocomponent Type II photoinitiator behavior). In addition, fast polymerization rates and high function conversions of acrylate are observed when an amine and/or an iodonium salt are added in systems. Benzophenone-carbazole PIs have good efficiencies in cationic photopolymerization (CP) upon LED @ 365 nm irradiation in the presence of iodonium salt. In contrast, other PIs without synergetic effect demonstrate unsatisfied photopolymerization profiles in the same conditions. The best PIS identified for the free radical photopolymerization were used in three-dimensional (3D) printing. Steady state photolysis and fluorescence quenching experiments were carried out to investigate the reactivity and the photochemistry and photophysical properties of PIs. The free radicals, generated from the studied PISs, are detected by the electron spin resonance - spin trapping technique. The proposed chemical mechanisms are provided and the structure/reactivity/efficiency relationships are also discussed. All the results showed that the benzophenone-carbazole PIs have a good application potential, and this work provides a rational design route for PI molecules. Remarkably, BPC2-BPC4, C6, C8 were never synthetized before; therefore, 5 of the 8 compounds are completely new.

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Section: Introductionmentioning

confidence: 99%

Monocomponent Photoinitiators based on Benzophenone-Carbazole Structure for LED Photoinitiating Systems and Application on 3D Printing

et al. 2020

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“…have been reported. [3,12,13] To improve the photochemical reactivity or obtain additional properties, dyes are usually modified with various substituents through chemical engineering. Traditional UV sensitive PIs are commonly introduced in the backbone of dyes absorbing in the visible range due to their well-established photochemical reactivities, the chromophores onto which these UV sensitive PIs are attached being in charge to redshift their absorption toward the visible region and provide high molar extinction coefficients (e.g., @405 nm) at wavelengths these PIs do not naturally absorb.…”

Section: In This Study a New Generation Of Photoinitiator (Pi) Basedmentioning

confidence: 99%

Novel Photoinitiators Based on Benzophenone‐Triphenylamine Hybrid Structure for LED Photopolymerization

Liu

Brunel

Sun

et al. 2020

Macromol. Rapid Commun.

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In this study, a new generation of photoinitiator (PI) based on hybrid structures combining benzophenone and triphenylamine is proposed. Remarkably, these photoinitiators (noted monofunctional benzophenone‐triphenylamine (MBP‐TPA) and trifunctional benzophenone‐triphenylamine (TBP‐TPA)) are designed and developed for the photopolymerization under light‐emitting diodes (LEDs). Benzoyl substituents connected with triphenylamine moiety contribute to the excellent absorption properties which results in both high final conversions and polymerization rates in free radical photopolymerization (FRP). Remarkably, TBP‐TPA owning trifunctional benzophenone group exhibits a better Type II PI behavior than well‐known 2‐isopropylthioxanthone for photopolymerization under LED@365 and 405 nm irradiation. FRP and cationic photopolymerization of TBP‐TPA‐based systems are applied on 3D printing experiments, and good profiles of the 3D patterns are observed. The high molecular weight of TBP‐TPA associated with it trifunctional character can also be very interesting for a better migration stability of PIs that is a huge challenge. The development of this new generation of photoinitiators based on benzophenone hybrid structures is a real breakthrough. It reveals that the novel versatile photoinitiators based on benzophenone‐triphenylamine hybrid structures have great potentials for future industrial applications (e.g., 3D printing, composites, etc.).

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“…Indeed, as shown in Figure 1 for a polystyrene latex with an average diameter of 112 nm containing fillers [21], light penetration can range from 600 µm at 400 nm up to 5 cm at 800 nm, enabling to revolutionize the scope of application of photopolymerization from coatings to the elaboration of thick samples [22]. At present, organic dyes used as visible light photosensitizers of polymerization have been extensively studied [23][24][25][26]. Interest for metal-free photoinitiators is notably motivated by the high costs of numerous metal precursors but also by the safety concerns raised by the use of transition metals.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

Noirbent

Dumur

2020

Catalysts

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Metal complexes are used in numerous chemical and photochemical processes in organic chemistry. Metal complexes have not been excluded from the interest of polymerists to convert liquid resins into solid materials. If iridium complexes have demonstrated their remarkable photochemical reactivity in polymerization, their high costs and their attested toxicities have rapidly discarded these complexes for further developments. Conversely, copper complexes are a blooming field of research in (photo) polymerization due to their low cost, easy syntheses, long-living excited state lifetimes, and their remarkable chemical and photochemical stabilities. Copper complexes can also be synthesized in solution and by mechanochemistry, paving the way towards the synthesis of photoinitiators by Green synthetic approaches. In this review, an overview of the different copper complexes reported to date is presented. Copper complexes are versatile candidates for polymerization, as these complexes are now widely used not only in photopolymerization, but also in redox and photoassisted redox polymerization processes.

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Recent advances on carbazole-based photoinitiators of polymerization

Cited by 89 publications

References 187 publications

Monocomponent Photoinitiators based on Benzophenone-Carbazole Structure for LED Photoinitiating Systems and Application on 3D Printing

Monocomponent Photoinitiators based on Benzophenone-Carbazole Structure for LED Photoinitiating Systems and Application on 3D Printing

Novel Photoinitiators Based on Benzophenone‐Triphenylamine Hybrid Structure for LED Photopolymerization

Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

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