Visible light‐induced polymerization of monooxiranes and 1,5,7,11‐tetraoxaspiro[5.5]undecanes

Pinzino, Charles S.; Chappelow, Cecil C.; Holder, Alvin A.; Morrill, Jason A.; Harris, C. David; Power, Martin D.; Eick, J. David

doi:10.1002/app.10578

Cited by 7 publications

(4 citation statements)

References 18 publications

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“…The possible initiating mechanism in systems containing a diaryliodonium salt in combination with CQ has been proposed by previous researchers . Irradiation of the CQ with visible light results in the formation of its singlet state, which is rapidly converted to its triplet state by intersystem crossing .…”

Section: Resultsmentioning

confidence: 97%

“…Irradiation of the CQ with visible light results in the formation of its singlet state, which is rapidly converted to its triplet state by intersystem crossing . The excited CQ molecule is initially reduced by a hydrogen donor (monomer or amine) to the ketyl radical which in turn is oxidized back to CQ by the iodonium salt . The resulting strong Brønsted acid derived from this process initiate the cationic ring‐opening polymerization.…”

Section: Resultsmentioning

confidence: 99%

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Encapsulants for light‐emitting diodes from visible light‐cured epoxy monomers

Schroeder

Erba

Arenas

et al. 2013

Polymers for Advanced Techs

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During the last decade, light‐emitting diodes (LEDs) have replaced incandescent, fluorescent, and neon lamps due to their ability to produce high luminosity at low currents and voltages. LEDs are currently encapsulated by thermally curable epoxy resins. However, long periods of curing at high temperature result in high consumption of energy and require stringent process control to avoid failure of the devices. In addition, the thermal cure results in yellowing of the encapsulant, which decreases the efficiency of the LED. In recent years, photoinitiated polymerization has received much interest as it congregates a wide range of economic and ecological benefits. Cationic photoinitiators, such as diaryliodonium salts, generate Brønsted acid in situ, which initiates polymerization. The process can be triggered on demand by irradiating the mixture with light. Results from the present research reveal that cycloaliphatic epoxy monomers, photoactivated with an iodonium salt and Camphorquinone, polymerize readily under visible light irradiation (470 nm) in the absence of external heating. The partial replacement of cycloaliphatic epoxy with aromatic diglycidyl ether of bisphenol‐A (DGEBA) is an effective means of improving the refractive index of the material and consequently the efficiency of the photoemission. Visible light polymerization of DGEBA pure proceeds at a slow rate; however, it is enhanced by the increase in temperature during the polymerization of the highly reactive cycloaliphatic monomer. From results obtained in the present research, it may be concluded that visible light polymerization of epoxy monomers is a promising route for the processing of LED encapsulants. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Encapsulants for light‐emitting diodes from visible light‐cured epoxy monomers

Schroeder

Erba

Arenas

et al. 2013

Polymers for Advanced Techs

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“…The alkoxyoxirane would produce a carbocation that is stabilized by the adjacent oxygen atom and whose structure is similar to that of the VE-derived carbocation (Scheme ); hence, the formed carbon–halogen bond may be sufficiently labile to be easily reactivated. The polymerization of MOMPO, however, has never been thoroughly investigated, although its polymerization via light-induced initiation has been reported . In this study, we first examined the cationic homopolymerization of MOMPO using metal chlorides as Lewis acid catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…The polymerization of MOMPO, however, has never been thoroughly investigated, although its polymerization via light-induced initiation has been reported. 18 In this study, we first examined the cationic homopolymerization of MOMPO using metal chlorides as Lewis acid catalysts. Copolymerizations with alkyl VEs were then examined on the basis of the results from the homopolymerization.…”

Section: ■ Introductionmentioning

confidence: 99%

Alkoxyoxirane, a Unique Cyclic Monomer: Controlled Cationic Homopolymerization Mediated by Long-Lived Species and Copolymerization with Vinyl Ether via Alkoxy Group Transfer

et al. 2014

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1-Methoxy-2-methylpropylene oxide (MOMPO), an alkoxyoxirane that can generate a carbocation adjacent to an alkoxy group via ring-opening, was demonstrated to polymerize in a controlled manner with the use of a metal chloride as a Lewis acid catalyst. The choice of the initiating system is critical for the successful controlled homopolymerization of this alkoxyoxirane; a GaCl3/THF system was observed to be the best combination for the initiating system. Furthermore, the copolymerization of MOMPO with isopropyl vinyl ether (IPVE) generated long-lived species when CF3SO3H/nBu4NI was used as the initiating system. Surprisingly, the reaction proceeded via the transfer of the alkoxy group in the IPVE unit. More specifically, the isopropoxy group at the penultimate IPVE unit transferred to the MOMPO-derived propagating cation after the crossover reaction from the IPVE-derived carbocation to MOMPO. This type of reaction creates a side group that possesses the ring-opened MOMPO structure with the isopropoxy group. The generation of copolymers via the “alkoxy-group transfer” mechanism is unique to the copolymerization in this study and was confirmed by 1H, 13C, and 2D NMR analyses and by the acid hydrolysis and subsequent reacetalization reactions of the products.

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The effect of hydroxyspiro‐orthocarbonates on the cationic photopolymerization of an epoxy resin and on the mechanical properties of the final polymer

Ortiz

Gómez

Duarte

et al. 2011

Polymer International

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It is well known that bicyclic compounds like spiro‐orthocarbonates (SOCs) have the ability to reduce or eliminate the shrinkage produced during polymerization. In the work reported, four different SOCs were prepared, two of them with one and two hydroxyl groups, respectively, another with two alkoxy groups and one reference compound without substituents. It was found that the SOCs with hydroxyl groups increased the photopolymerization rate and conversion of an epoxycycloaliphatic monomer, while the compound with butoxy groups had an antagonistic effect, reducing both photopolymerization rate and conversion, due to the basic character of the ether groups. The reference compound did not display accelerating effects but it did increase slightly the conversion. Dynamic mechanical analysis revealed that the SOC with two hydroxyl groups increased the values of storage modulus of the obtained polymer in comparison with the polymer from pristine monomer. This may be due to the multifunctionality of this compound that induced a higher level of crosslinking, while the SOC with one hydroxyl group had the opposite effect, decreasing the viscoelastic property values of the polymer due to chain‐transfer reactions originated by the hydroxyl groups. The SOC with two hydroxyl groups was the more efficient of the studied compounds in reducing the shrinkage of the cured polyether. Copyright © 2011 Society of Chemical Industry

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Visible light‐induced polymerization of monooxiranes and 1,5,7,11‐tetraoxaspiro[5.5]undecanes

Cited by 7 publications

References 18 publications

Encapsulants for light‐emitting diodes from visible light‐cured epoxy monomers

Encapsulants for light‐emitting diodes from visible light‐cured epoxy monomers

Alkoxyoxirane, a Unique Cyclic Monomer: Controlled Cationic Homopolymerization Mediated by Long-Lived Species and Copolymerization with Vinyl Ether via Alkoxy Group Transfer

The effect of hydroxyspiro‐orthocarbonates on the cationic photopolymerization of an epoxy resin and on the mechanical properties of the final polymer

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