Visible Light Induced Cationic Polymerization of Epoxides by Using Multiwalled Carbon Nanotubes

Sangermano, Marco; Rodriguez, D. E.; González, Mónica C.; Laurenti, Enzo; Yaǧcı, Yusuf

doi:10.1002/marc.201800250

Cited by 36 publications

(32 citation statements)

References 33 publications

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“…In order to match with the wavelength requirements for certain practical applications, the sensitivity range of onium salts was extended to higher wavelengths by using free radical photoinitiators, charge transfer complexes, and singlet and triplet photosensitizers . It was also shown that nanoparticles and highly conjugated molecules can also sensitize cationic polymerization by photoinduced electron transfer reactions. Among all these strategies, so‐called free radical promoted cationic polymerization outlined in Scheme is most widely used methodology as many free radical photointiators acting at broad wavelength range are readily available.…”

Section: Methodsmentioning

confidence: 99%

Near‐Infrared‐Induced Cationic Polymerization Initiated by Using Upconverting Nanoparticles and Titanocene

Zhu

Guan

et al. 2019

Macromol. Rapid Commun.

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Although most of the technologically applied photochemical processes are based on free radical polymerization, after the discovery of onium salt photochemistry by Crivello, [11] photoinitiated cationic polymerization has gained interest due to their thermal stability, solubility in most of the cationically polymerizable monomers, insensitivity to oxygen and high quantum efficiency to generate reactive species. [3] The existing onium salt-based photoinitiating systems for cationic polymerization include iodonium, [11] sulfonium, [12] alkoxy pyridinium, [13] and phosphonium [14] salts. However, unless additional chromophores are incorporated [15] into the salt structure the absorption of these salts at above 300 nm is rather low. In order to match with the wavelength requirements for certain practical applications, the sensitivity range of onium salts was extended to higher wavelengths by using free radical photoinitiators, [16] charge transfer complexes, [17] and singlet and triplet photosensitizers. [18] It was also shown that nanoparticles [19] and highly conjugated molecules [20] can also sensitize cationic polymerization by photoinduced electron transfer reactions. Among all these strategies, so-called free radical promoted cationic polymerization outlined in Scheme 1 is most widely used methodology as many free radical photointiators acting at broad wavelength range are readily available.In this process, photochemically formed electron donor radicals are oxidized by onium salts. The cations thus generated are used as initiating species for cationic polymerizations. As a consequence of the redox reaction, aryl radicals are also generated that can undergo various subsequent reactions resulting in the chemical amplification of the photons absorbed by the system. Free radical photoinitiators including aromatic carbonyl compounds, [21] acyl phosphine oxides, [22] acyl germanes, [23] organotellurium, [24] manganese carbonyl compounds, [25] and silanes [26] were successfully used to promote cationic polymerizations Despite the fact that the above-mentioned indirect systems can successfully initiate cationic polymerization at the near UV and visible range, [3] it is highly desirable to extend the spectral sensitivity to lower energy irradiation, such as nonharmful near-infrared (NIR) region which also limits side reactions resulting in self-initiation of monomers and degradation of already-formed polymers and oligomers. However, until recently, reports describing NIR sensitized photopolymerizations are exceedingly scarce. Several examples reported in the literature are mostly based on cyanine dyes and polymethines. [27] Besides their use in conventional photopolymerization formulations, polymethines with zwitter ionic structure Photopolymerization A new near-infrared (NIR)-sensitized photoinitiating system for free-radicalpromoted cationic polymerization of oxirane and vinyl monomers such as cyclohexene oxide, and n-butyl vinyl ether (BVE), and N-vinyl carbazole (NVC) is described. A three-component photoinitiating ...

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Section: Methodsmentioning

confidence: 99%

Near‐Infrared‐Induced Cationic Polymerization Initiated by Using Upconverting Nanoparticles and Titanocene

Zhu

Guan

et al. 2019

Macromol. Rapid Commun.

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“…In their studies, Sangermano et al [ 87 ] demonstrated the effect of multi walled carbon nanotubes (MWCNT) as free radical generator induced by visible light for the cationic polymerization of bis-cycloaliphatic epoxy using diaryliodonium salt. The mechanism involves a cationic polymerization of epoxides through visible light generated electrons and holes from MWCNTs ( Figure 3 A), followed by electron transfer reactions with the iodonium salt ( Figure 3 B) [ 87 ].…”

Section: Onium Salt Photoinitiators For Different Epoxy Monomersmentioning

confidence: 99%

Review on UV-Induced Cationic Frontal Polymerization of Epoxy Monomers

et al. 2020

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Ultraviolet (UV)-induced cationic frontal polymerization has emerged as a novel technique that allows rapid curing of various epoxy monomers upon UV irradiation within a few seconds. In the presence of a diaryliodonium salt photoinitiator together with a thermal radical initiator, the cationic ring opening polymerization of an epoxide monomer is auto-accelerated in the form of a self-propagating front upon UV irradiation. This hot propagating front generates the required enthalpy to sustain curing reaction throughout the resin formulation without further need for UV irradiation. This unique reaction pathway makes the cationic frontal polymerization a promising route towards the efficient curing of epoxy-based thermosetting resins and related composite structures. This review represents a comprehensive overview of the mechanism and progress of UV-induced cationic frontal polymerization of epoxy monomers that have been reported so far in literature. At the same time, this review covers important aspects on the frontal polymerization of various epoxide monomers involving the chemistry of the initiators, the effect of appropriate sensitizers, diluents and fillers.

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“…Fors [33,34], Nicewicz [35], and Boydston [36] et al found that pyrylium salts can drive the polymerization of vinyl ethers, 4-methoxystyrene, and norbornenes, through cationic pathways or ring-opening metathesis mechanisms. Yagci et al [37,38,39,40,41,42,43,44] developed visible light-cationic and radical polymerizations using various non-metallic materials. Even so, the very limited category and quantity of organic photocatalysts have motivated researchers to exploit new organic catalysts.…”

Section: Introductionmentioning

confidence: 99%

PET-RAFT Polymerization Catalyzed by Small Organic Molecule under Green Light Irradiation

et al. 2019

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Photocatalyzed polymerization using organic molecules as catalysts has attracted broad interest because of its easy operation in ambient environments and low toxicity compared with metallic catalysts. In this work, we reported that 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT) can act as an efficient photoredox catalyst for photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization under green light irradiation. Well-defined (co)polymers can be obtained using this technique without any additional additives like noble metals and electron donors or acceptors. The living characteristics of polymerization were verified by kinetic study and the narrow dispersity (Đ) of the produced polymer. Excellent chain-end fidelity was demonstrated through chain extension as well. In addition, this technique showed great potential for various RAFT agents and monomers including acrylates and acrylamides.

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Visible Light Induced Cationic Polymerization of Epoxides by Using Multiwalled Carbon Nanotubes

Cited by 36 publications

References 33 publications

Near‐Infrared‐Induced Cationic Polymerization Initiated by Using Upconverting Nanoparticles and Titanocene

Near‐Infrared‐Induced Cationic Polymerization Initiated by Using Upconverting Nanoparticles and Titanocene

Review on UV-Induced Cationic Frontal Polymerization of Epoxy Monomers

PET-RAFT Polymerization Catalyzed by Small Organic Molecule under Green Light Irradiation

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