No Reduction of CuBr<sub>2</sub> during Cu(0)-Catalyzed Living Radical Polymerization of Methyl Acrylate in DMSO at 25 °C

Levere, Martin E.; Nguyen, Nga H.; Percéc, Virgil

doi:10.1021/ma301547n

Cited by 67 publications

(91 citation statements)

References 59 publications

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“…68 For example, although 100% retention of endgroup functionality was claimed in the literature, 74 the UV−Vis spectra showed that under the same conditions more than 1% of CuBr 2 /Me 6 TREN was formed with respect to the initiator. 126 This shows that at least 2% of the end groups were lost by termination, according to the principle of halogen conservation.…”

Section: Macromoleculesmentioning

confidence: 92%

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Reversible-Deactivation Radical Polymerization in the Presence of Metallic Copper. A Critical Assessment of the SARA ATRP and SET-LRP Mechanisms

et al. 2013

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Reversible-deactivation radical polymerization (RDRP) in the presence of Cu0 is a versatile technique that can be used to create well-controlled polymers with complex architectures. Despite the facile nature of the technique, there has been a vigorous debate in the literature as to the\ud mechanism of the reaction. One proposed mechanism, named supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP), has CuI as the major activator of alkyl halides, Cu0 acting as a supplemental activator, an inner-sphere electron transfer occurring during the activation step, and relatively slow comproportionation and disproportionation. In SARA ATRP slow activation of alkyl halides by Cu0 and comproportionation of CuII with Cu0 compensates for the small number of radicals lost to termination reactions. Alternatively, a mechanism named single electron transfer living radical polymerization (SET-LRP) assumes that the CuI species do not activate alkyl halides, but undergo instantaneous disproportionation, and that the relatively rapid polymerization is due to a fast reaction between alkyl halides and “nascent” Cu0 through an outer-sphere electron transfer. In this article a critical assessment of the experimental data are presented on the polymerization of methyl acrylate in DMSO with Me6TREN as the ligand in the presence of Cu0, in order to discriminate between these two mechanisms. The experimental data agree with the SARA ATRP mechanism, since the activation of alkyl halides by CuI species is significantly faster than Cu0, the activation step involves inner-sphere electron transfer rather than an outer-sphere electron transfer, and in DMSO comproportionation is slow but occurs faster than disproportionation, and activation by CuI species is much faster than disproportionation. The rate of deactivation by CuII is essentially the same as the rate of activation by CuI, and the system is under ATRP equilibrium. The role of Cu0 in this system is to slowly and continuously supply CuI activating species and radicals, by supplemental activation and comproportionation, to compensate for CuI lost due to\ud the unavoidable radical termination reactions. With the mechanistic understanding gained by analyzing the experimental data in the literature, the reaction conditions in SARA ATRP can be tailored toward efficient synthesis of a new generation of complex architectures and functional materials

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Section: Macromoleculesmentioning

confidence: 92%

“…74,126,127 The key features of the SET-LRP mechanism are outlined in Scheme 5, presented in the same way as in Scheme 4, although some reactions are omitted in SET-LRP schematics, as shown in the middle part of Scheme 3. Therefore, SET-LRP does not include any significant kinetic contributions from alkyl halide activation by Cu I .…”

Section: Macromoleculesmentioning

confidence: 99%

Reversible-Deactivation Radical Polymerization in the Presence of Metallic Copper. A Critical Assessment of the SARA ATRP and SET-LRP Mechanisms

et al. 2013

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“…As the SET-LRP of methyl acrylate (MA) is a well-studied and understood system, [40][41][42][43][44][45][46] the initiator-fixed silica nanoparticles were used to mediate the growth of poly(methyl acrylate) brushes from the particle surface. All polymerisations were carried out in DMSO at 30 °C using a Cu(0)/Me 6 TREN catalytic system in the presence of a free (sacrificial) initiator, ethyl 2-bromoisobutyrate (EBiB), unless specified otherwise.…”

Section: Resultsmentioning

confidence: 99%

Surface-initiated SET living radical polymerisation for the synthesis of silica–polymer core–shell nanoparticles

2016

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Sébastien. (2016) Surface-initiated SET living radical polymerisation for the synthesis of silica-polymer core-shell nanoparticles. Polymer Chemistry, 7 (39). pp. 6075-6083. Permanent WRAP URL:http://wrap.warwick.ac.uk/83840 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work of researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement:First published by Royal Society of Chemistry 2016 http://dx.doi.org/10.1039/C6PY01290F A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. AbstractWe report the use of surface-initiated single-electron transfer living radical polymerisation (SI SET-LRP) to prepare inorganic-organic core-shell nanoparticles with functional grafted chains of high molecular weight. The potential of SI SET-LRP is demonstrated by the preparation of a series of silica-polymer core-shell materials from a silica nanoparticle template bearing a bromo ester initiating group in the presence of a free initiator, with detailed kinetic investigations using methyl acrylate and tert-butyl acrylate. Under optimised polymerisation conditions, concentrated polymer brushes with grafting densities as high as 0.8 chains nm -2 and relatively high molecular weight polymer grafts (degree of polymerisation, DP n , up to 1000) were achieved whilst employing a heterogeneous copper(0) wire catalyst at low polymerisation temperatures. Under optimal conditions, the polymer shell grows similarly to the free polymer with increasing monomer conversion to produce well-defined monodisperse particles with a narrow size distribution. The particle uniformity results in the formation of particle assemblies that display long-range 2D and 3D order, as characterised by electron microscopy.2

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“…The observation of disproportionation of copper(I) salts in water and of copper(I)/ligand complexes in DMSO led this group to propose that in these systems (and many others which had been considered to follow the ATRP mechanism) copper(0) was the primary activating species, and that concentrations of copper(I) were essentially zero as a result of rapid disproportionation. Additionally, the generation of copper(II) was thought to remove the need for build-up of copper(II) deactivating species via the persistent radical effect, thus providing low (or even zero (11)(12)(13)(14)) levels of termination from the beginning of the reaction.…”

Section: Scheme 1 Reactions Of Copper Metal In Atom Transfer Radicalmentioning

confidence: 99%

“…However, a detailed kinetic study of the polymerization of methyl acrylate in DMSO solution carried out by Percec and coworkers (11) showed that the rate of generation of copper decreased as the reaction proceeded. This was not a result of loss of dormant polymer chains through termination, which was less than 4% as estimated by the increase in copper concentration during the reaction (using the principle of halogen conservation (34)) and was too small to be measured by NMR (estimated at <0.5% by the authors of the study).…”

Section: Chain Length Dependence Of K T and K A0mentioning

confidence: 99%

Kinetic Studies of Elementary Reactions in SET-LRP / SARA ATRP

Nicolas

Perrier

Harrisson

2015

ACS Symposium Series

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A kinetic scheme for controlled radical polymerization in the presence of copper is developed, first neglecting comproportionation or disproportionation reactions, then taking them into account. Experimental results on the kinetics of the elementary reactions of comproportionation, activation by copper(0) and biradical termination are presented, showing solvent effects on activation and comproportionation reactions and chain length dependence of activation and termination. Unusually high rates of termination are observed in controlled radical polymerizations in the presence of copper; around an order of magnitude faster than in conventional or RAFT polymerizations.

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No Reduction of CuBr₂ during Cu(0)-Catalyzed Living Radical Polymerization of Methyl Acrylate in DMSO at 25 °C

Cited by 67 publications

References 59 publications

Reversible-Deactivation Radical Polymerization in the Presence of Metallic Copper. A Critical Assessment of the SARA ATRP and SET-LRP Mechanisms

Reversible-Deactivation Radical Polymerization in the Presence of Metallic Copper. A Critical Assessment of the SARA ATRP and SET-LRP Mechanisms

Surface-initiated SET living radical polymerisation for the synthesis of silica–polymer core–shell nanoparticles

Kinetic Studies of Elementary Reactions in SET-LRP / SARA ATRP

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No Reduction of CuBr2 during Cu(0)-Catalyzed Living Radical Polymerization of Methyl Acrylate in DMSO at 25 °C

Cited by 67 publications

References 59 publications

Reversible-Deactivation Radical Polymerization in the Presence of Metallic Copper. A Critical Assessment of the SARA ATRP and SET-LRP Mechanisms

Reversible-Deactivation Radical Polymerization in the Presence of Metallic Copper. A Critical Assessment of the SARA ATRP and SET-LRP Mechanisms

Surface-initiated SET living radical polymerisation for the synthesis of silica–polymer core–shell nanoparticles

Kinetic Studies of Elementary Reactions in SET-LRP / SARA ATRP

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No Reduction of CuBr₂ during Cu(0)-Catalyzed Living Radical Polymerization of Methyl Acrylate in DMSO at 25 °C