Seeing the Light: Advancing Materials Chemistry through Photopolymerization

Corrigan, Nathaniel; Yeow, Jonathan; Judzewitsch, Peter R.; Xu, Jiangtao; Boyer, Cyrille

doi:10.1002/ange.201805473

Cited by 147 publications

(73 citation statements)

References 236 publications

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“…However, visible emitting light sources such as LEDs are of great interest due to their lower price, lower energy consumption, and safer operating conditions. The use of these irradiation sources requires the development of new photoinitiating systems (PISs) absorbing in the visible spectral range, typically in the 400–500 nm region . Few Type I photoinitiators (PIs) are reactive under visible light exposure (e.g., titanocene derivatives).…”

Section: Methodsmentioning

confidence: 99%

1‐Aryl‐2‐(triisopropylsilyl)ethane‐1,2‐diones: Toward a New Class of Visible Type I Photoinitiators for Free Radical Polymerization of Methacrylates

Kirschner

Baralle

Graff

et al. 2019

Macromol. Rapid Commun.

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well-known alkyl phenylglyoxylates (APG) due to the introduction of a (trialkylsilyl) moiety. [15] The alkyl(trialkylsilyl)glyoxylates are high performance PIs efficient under visible light exposure and especially blue light irradiation. Based on molecular orbital calculations, the objective of this article is to replace the alkoxy group of the ester function of the alkyl(trialkylsilyl)glyoxylate by an aryl group to form 1-aryl-2-(triisopropylsilyl)ethane-1,2-diones (SEDs, Scheme 1). These compounds should present a bathochromic shift of the absorption properties of the PIs. To the best of our knowledge, SEDs were never reported in the literature as visible light photoinitiators. The reactivity of SEDs is determined as PIs for the free radical polymerization of a urethane dimethacrylate (UDMA-Scheme 2) upon exposure to blue and green LEDs. Their bleaching properties are particularly worthwhile, that is, better than titanocene or CQ/ amine systems (Scheme 2).The SEDs, 1-phenyl-2-(triisopropylsilyl)ethane-1,2-dione (SED1) and 1-(3,4,5-trimethoxyphenyl)-2-(triisopropylsilyl)ethane-1,2-dione (SED2), were prepared in two steps (Scheme 1, Supporting Information): 1) Pd-catalyzed Sonogashira cross-coupling between an aryl iodide and (triisopropylsilyl)acetylene in the presence of CuI, diisopropylamine in MeCN leading almost quantitatively to the desired alkynes 1a and 1b; [16] 2) oxidation of the triple bond using RuO 2 , NaIO 4 in a mixture of CCl 4 /MeCN/H 2 O giving SED1 and SED2. [17] It is noteworthy that step 2 proceeds in low yield due to a partial degradation of 1a and 1b under the oxidation conditions. However, before Photoinitiators 1-Aryl-2-(triisopropylsilyl)ethane-1,2-diones (SEDs) are proposed here as a new class of visible Type I photoinitiators (PIs) for free radical polymerization under air upon exposure to blue (@455 nm) and green (@520 nm) LEDs. Remarkably, these new systems present good polymerization performances and excellent bleaching properties compared to camphorquinone-based systems, and transparent polymers are obtained upon visible light irradiation. Real-time Fourier transform infrared spectroscopy is used to monitor the polymerization profiles. Molecular orbital calculations are also carried out for a better understanding of the structure/reactivity relationship of the photoinitiators.Photopolymerization techniques have been widely studied and used over the past decades. Due to several advantages compared to thermal polymerization methods, photopolymerization has many industrial applications such as coatings, inks, adhesives, photolithography, 3D printing, and dentistry. [1,2] Nevertheless, the majority of the commercially available photoinitiators is UV sensitive. [3,4] However, visible emitting light sources such as LEDs are of great interest due to their lower price, lower energy consumption, and safer operating conditions. The use of these irradiation sources requires the development of new photoinitiating systems (PISs) absorbing in the visible spectral range, typically in the 400-500 ...

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Section: Methodsmentioning

confidence: 99%

1‐Aryl‐2‐(triisopropylsilyl)ethane‐1,2‐diones: Toward a New Class of Visible Type I Photoinitiators for Free Radical Polymerization of Methacrylates

Kirschner

Baralle

Graff

et al. 2019

Macromol. Rapid Commun.

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“…Photochemistry is an attractive methodology to merge with RDRP technique, such as RAFT polymerization due to its ability to give facile access to high energy intermediates under relatively mild conditions . Light is an attractive source of energy for polymerization reactions because it is readily available, highly tunable, and offers control over both the temporal and spatial domains . Photochemically activated RAFT polymerization is a growing field of research .…”

Section: Introductionmentioning

confidence: 99%

Intrinsic and Catalyzed Photochemistry of Phenylvinylketone for Wavelength‐Sensitive Controlled Polymerization

et al. 2019

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Reversible addition-fragmentation chain transfer (RAFT) photopolymerization of phenylvinylketone (PVK) is investigated. The polymerization is investigated both in the presence of two photocatalysts (iridium tris(phenylpyridine (Ir(ppy) 3 ) and zinc tetraphenylporphyrin (ZnTPP)). The polymerization was efficient in the absence of photocatalyst, and accelerated by Ir(ppy) 3 , whereas ZnTPP was found to lead to retardation of polymerization. In all cases, well-controlled polymers were synthesized with linear growth in M n with conversion and narrow molecular weight distributions. The observed photopolymerization kinetics were consistent with a Norrish Type 1 reaction of PVK to give two radicals. The polymerization kinetics were investigated as a function of wavelength, with the reaction rate being fastest with blue irradiation (440 nm), which is surprisingly far from the absorption maximum of PVK and Ir(ppy) 3 . Photodegradation of PVK was observed under UV irradiation, but the polymers were stable against visible light. block copolymers, [45] and PET-RAFT vinyl ketone work using Eosin Y as the photoredox catalyst. [46,47] The previous work from our group prompted further study, as only polymerization under catalyst free conditions and under two wavelengths of light were studied. As photodegradable polymers are an important class of polymers and photoRAFT methods are useful in a wide range of applications, a systematic study of photo-RAFT and PET-RAFT polymerization of PVK was undertaken. 2 3 4 5 6 7 8

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“…In recent years, photochemistry has been a highly active research field attributed to its capability to drive economic chemical process . In comparison to conventional thermal processes, photochemical approaches allow for more precise and efficient transformations.…”

Section: Introductionmentioning

confidence: 99%

Photo‐Induced Depolymerisation: Recent Advances and Future Challenges

et al. 2019

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Facing the growing environmental issues provoked by the use of nondegradable polymers in many fields (for example, packing, building, and clothing), tremendous efforts have been made to explore photodegradable materials to alleviate the increase in plastic pollution. Photodegradable materials would exploit significant advantages presented by the use of light, such as abundance, safety and the ability to easily tune intensity and wavelength. In particular, photo‐induced depolymerisation has received increasing attention, which could enable polymers to degrade to their original monomers or small molecules under certain photoirradiation conditions. Most importantly, the obtained molecules or monomers via photo‐induced depolymerisation could be conveniently recycled or further transformed to other high‐value‐added products, which is of great benefit for environmental protection. This Review summarizes recent advances in the growing field of photo‐induced depolymerisation and also considers future challenges that must be addressed. It aims to encourage new researchers to enter this flourishing area and presents a brief guide to the field.

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Seeing the Light: Advancing Materials Chemistry through Photopolymerization

Cited by 147 publications

References 236 publications

1‐Aryl‐2‐(triisopropylsilyl)ethane‐1,2‐diones: Toward a New Class of Visible Type I Photoinitiators for Free Radical Polymerization of Methacrylates

1‐Aryl‐2‐(triisopropylsilyl)ethane‐1,2‐diones: Toward a New Class of Visible Type I Photoinitiators for Free Radical Polymerization of Methacrylates

Intrinsic and Catalyzed Photochemistry of Phenylvinylketone for Wavelength‐Sensitive Controlled Polymerization

Photo‐Induced Depolymerisation: Recent Advances and Future Challenges

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