Understanding Organometallic-Mediated Radical Polymerization with an Iron(II) Amine–Bis(phenolate)

Coward, Daniel L.; Lake, Benjamin R. M.; Shaver, Michael P.

doi:10.1021/acs.organomet.7b00473

Cited by 17 publications

(17 citation statements)

References 44 publications

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“…More elaborated ligands such as iminopyridine‐ and aminopyridine‐based ligands were explored in Fe‐based ATRP . Amine‐bis(phenolate) (ABP, Figure ) ligands have shown promise in the controlled polymerization of MMA and St, for which concurrent ATRP and OMRP mechanisms were proposed …”

Section: Ru‐ and Fe‐based Atrp Catalystsmentioning

confidence: 99%

Atom Transfer Radical Polymerization: Billion Times More Active Catalysts and New Initiation Systems

Ribelli

Lorandi

Fantin

et al. 2018

Macromol. Rapid Commun.

235

184

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polymerizing styrene in the presence of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) radicals. [10] Later, Wayland et al. used a cobalt(II) porphyrin complex to reversibly trap radical species during the polymerization of acrylate monomers, which showed living features: i) linear increase of polymer MW with monomer conversion, and ii) narrow MWD. [11] These techniques set the basis for the development of nitroxide-mediated polymerization (NMP) [12,13] and organometallic mediated radical polymerization (OMRP). [14][15][16] Within the past three decades, controlled radical polymerization (CRP) has been established as a new field in polymer chemistry, in which exceptional control was achieved over polymer architectures, thus enabling the preparation of commercially relevant polymer-based materials for advanced applications. Following IUPAC recommendations, CRP should be termed as reversible deactivation radical polymerization (RDRP). [17] Besides the aforementioned NMP and OMRP, the most affirmed RDRPs are atom transfer radical polymerization (ATRP) [18][19][20] and reversible additionfragmentation chain transfer (RAFT) polymerization. [21] RDRP ensures comparable degree of control as living ionic polymerization, while retaining the versatility and the scope of conventional radical polymerization. The fraction of terminated chains in RDRP is small, typically below a few mol%. Polymers and copolymers prepared by RDRP methods can have defined topologies (stars, brushes, networks, combs), compositions (block, gradient, graft, alternate) and chain-end functionalities. [22] This review will focus on ATRP, with particular attention to the design and application of progressively more active and selective copper-based catalysts, and the development of novel, more benign initiation systems. The correlation between the structure of Cu complexes and their catalytic activity will be discussed in detail, also taking into account the effect of solvent and, when present, surfactants and other additives. Mechanisms of Reversible Deactivation Radical Polymerization ProcessesThe core of all RDRP systems is the increase of chain lifetime by reversibly deactivating the propagating radical species, thus forming dormant species that can be subsequently reactivated. As opposed to conventional RP in which the 25 Years of ATRP Approaching 25 years since its invention, atom transfer radical polymerization (ATRP) is established as a powerful technique to prepare precisely defined polymeric materials. This perspective focuses on the relation between structure and activity of ATRP catalysts, and the consequent choice of the initiating system, which are paramount aspects to well-controlled polymerizations. The ATRP mechanism is discussed, including the effect of kinetic and thermodynamic parameters and side reactions affecting the catalyst. The coordination chemistry and activity of copper complexes used in ATRP are reviewed in chronological order, while emphasizing the structure-activity correlation. ATRP-initiating systems are described, from ...

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Section: Ru‐ and Fe‐based Atrp Catalystsmentioning

confidence: 99%

Atom Transfer Radical Polymerization: Billion Times More Active Catalysts and New Initiation Systems

Ribelli

Lorandi

Fantin

et al. 2018

Macromol. Rapid Commun.

235

184

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“…In contrast, iron catalysts strongly react with both tertiary and phenylsubstituted radicals. 41,42 Effect of Catalyst on the ATRP and OMRP Parameters. Table 3 reports the results of CV simulation for three catalysts of the TPMA family (structures in Scheme 2), with the initiator MBP in DMF.…”

Section: Introductionmentioning

confidence: 99%

Impact of Organometallic Intermediates on Copper-Catalyzed Atom Transfer Radical Polymerization

et al. 2019

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In atom transfer radical polymerization (ATRP), radicals (R •) can react with Cu I /L catalysts forming organometallic complexes, R-Cu II /L (L = N-based ligand). R-Cu II /L favors additional catalyzed radical termination (CRT) pathways, which should be understood and harnessed to tune the polymerization outcome. Therefore, the preparation of precise polymer architectures by ATRP depends on the stability and on the role of R-Cu II /L intermediates. Herein, spectroscopic and electrochemical techniques were used to quantify the thermodynamic and kinetic parameters of the interactions between radicals and Cu catalysts. The effects of radical structure, catalyst structure, and solvent nature were investigated. The stability of R-Cu II /L depends on the radical stabilizing group in the following order: cyano > ester > phenyl. Primary radicals form the most stable R-Cu II /L species. Overall, the stability of R-Cu II /L does not significantly depend on the electronic properties of the ligand, contrary to the ATRP activity. Under typical ATRP conditions, the R-Cu II /L build-up and the CRT contribution may be suppressed by using more ATRP-active catalysts or solvents that promote a higher ATRP activity.

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“…Control over chain growth was proposed to mainly involve the ATRP pathway as well as minor contribution of the OMRP mechanism. In the absence of ATRP alkyl halide initiators, use of an amine-bis(phenolate) iron (II) complex enabled moderate control over polymerization of methacrylate or styrene monomers via OMRP mechanism [60][61][62]. A phenolate-bis(pyridyl)amine ligand with monoanionic phenolate group was also used for iron-catalyzed ATRP but showed less efficient control over polymerization compared to the dianionic bisphenolate ligands [63].…”

Section: Nitrogen-based Ligandsmentioning

confidence: 99%

Iron Catalysts in Atom Transfer Radical Polymerization

Dadashi‐Silab

Matyjaszewski

2020

Molecules

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Catalysts are essential for mediating a controlled polymerization in atom transfer radical polymerization (ATRP). Copper-based catalysts are widely explored in ATRP and are highly efficient, leading to well-controlled polymerization of a variety of functional monomers. In addition to copper, iron-based complexes offer new opportunities in ATRP catalysis to develop environmentally friendly, less toxic, inexpensive, and abundant catalytic systems. Despite the high efficiency of iron catalysts in controlling polymerization of various monomers including methacrylates and styrene, ATRP of acrylate-based monomers by iron catalysts still remains a challenge. In this paper, we review the fundamentals and recent advances of iron-catalyzed ATRP focusing on development of ligands, catalyst design, and techniques used for iron catalysis in ATRP.

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Understanding Organometallic-Mediated Radical Polymerization with an Iron(II) Amine–Bis(phenolate)

Cited by 17 publications

References 44 publications

Atom Transfer Radical Polymerization: Billion Times More Active Catalysts and New Initiation Systems

Atom Transfer Radical Polymerization: Billion Times More Active Catalysts and New Initiation Systems

Impact of Organometallic Intermediates on Copper-Catalyzed Atom Transfer Radical Polymerization

Iron Catalysts in Atom Transfer Radical Polymerization

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