Organocatalyzed Photo‐Atom Transfer Radical Polymerization of Methacrylic Acid in Continuous Flow and Surface Grafting

Ramakers, Gijs; Krivcov, Alexander; Trouillet, Vanessa; Welle, Alexander; Möbius, H.‐H.; Junkers, Thomas

doi:10.1002/marc.201700423

Cited by 37 publications

(35 citation statements)

References 46 publications

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“…Other o ATRP catalysts have been synthesized and studied, which can be subdivided into five main classes including polycyclic aromatic hydrocarbons (such as perylene), phenothiazines, dihydrophenazines, phenoxazines, and carbazoles ( Figure ). o ATRP has been used to synthesize star copolymers through a core‐first approach as well as employed in a continuous flow reactor …”

Section: Development Of Atrp Initiation Systemsmentioning

confidence: 99%

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

Ribelli

Lorandi

Fantin

et al. 2018

Macromol. Rapid Commun.

225

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: Development Of Atrp Initiation Systemsmentioning

confidence: 99%

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

Ribelli

Lorandi

Fantin

et al. 2018

Macromol. Rapid Commun.

225

184

View full text Add to dashboard Cite

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“…[17f-g] Despite advances in PC design, O-ATRP has largely been limited to polymerization of methacrylate monomers,but the controlled polymerization of other monomers is highly desired. [18] Poly(acrylates) possess disparate thermal and mechanical properties,e nabling widespread industrial and academic use,i ncluding drug delivery,s uperabsorbent materials,c oatings,a dhesives and additive manufacturing. [19] As such, we sought to leverage current understanding of organic PC design to target the O-ATRP of acrylate monomers.T he CRP of acrylates is inherently challenging because of high k p , with values ranging from 15 000 to 24 000 Lmol À1 s À1 , [20] an order of magnitude larger than methacrylates.F urthermore, acrylate chain-end groups containing bromides are more difficult to reduce compared to the corresponding methacrylates,emphasizing the need for efficient PCs for activation.…”

Section: Introductionmentioning

confidence: 99%

Dimethyl Dihydroacridines as Photocatalysts in Organocatalyzed Atom Transfer Radical Polymerization of Acrylate Monomers

2020

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Development of photocatalysts (PCs) with diverse properties has been essential in the advancement of organocatalyzeda tom transfer radical polymerization (O-ATRP). Dimethyl dihydroacridines are presented here as anew family of organic PCs,for the first time enabling controlled polymerization of challenging acrylate monomers by O-ATRP.S tructure-property relationships for seven PCs are established, demonstrating tunable photochemical and electrochemical properties,and accessing astrongly oxidizing 2 PCC + intermediate for efficient deactivation. In O-ATRP,t he combination of PC,i mplementation of continuous-flowr eactors,a nd promotion of deactivation through addition of LiBr are critical to producing well-defined acrylate polymers with dispersities as low as 1.12. The utility of this approach is established through demonstration of the oxygen-tolerance of the system and application to diverse acrylate monomers,i ncluding the synthesis of well-defined di-and triblockcopolymers. Figure 1. a) Proposed mechanism of O-ATRP. b) Previously reported PCs developed for O-ATRP (left) with the new dimethyl-dihydroacridine PC family investigatedi nthis work (right).

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“…One approach to circumvent these problems has been reported by Ramerks et. al, using organocatalyzed photo‐atom transfer radical polymerization of methacrylic acid, grafting layers 8–10 nm in thickness . Another leap forward toward direct, well‐controlled ATRP of methacrylic acid that has been recently described, involves the use of supplemental activation reducing agent (SARA) ATRP and electrochemical ATRP (eATRP) with the addition of electrolytes and acid to the reaction solution .…”

Section: Introductionmentioning

confidence: 99%

An Acid Test: Facile SI‐ARGET‐ATRP of Methacrylic Acid

Michl

Jung

Pertoldi

et al. 2018

Macro Chemistry & Physics

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Atom transfer radical polymerization (ATRP) of methacrylic acid (MAA) is challenging. Herein is reported a study of conditions for facile surface‐initiated ATRP by activator regenerated electron transfer (SI‐ARGET‐ATRP) growth of poly‐methacrylic acid (PMAA) chains from a plasma polymer surface bearing surface‐immobilized α‐bromoisobutyryl bromide, with no deoxygenation required. Factors that affect PMAA polymer growth off the surface under ARGET‐ATRP conditions are systematically investigated, such as monomer/catalyst ratio, solvent, and, most importantly, addition of salts and change of pH. While the concentrations of the copper catalyst and acid affect grafting, the most pronounced effect arises from the concentration of chloride ions. Adding 0.1 m NaCl and acidifying the reaction solution to pH 3 offers the best trade‐off between reaction rate and reproducibility; yielding ≈60 nm thick PMAA graft polymers in 1 h under ambient conditions. Using this easily scalable recipe and surface analysis, the grafted polymers are verified to be pure PMAA and the graft coatings to be homogenous across a substrate of 100 mm diameter.

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Organocatalyzed Photo‐Atom Transfer Radical Polymerization of Methacrylic Acid in Continuous Flow and Surface Grafting

Cited by 37 publications

References 46 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

Dimethyl Dihydroacridines as Photocatalysts in Organocatalyzed Atom Transfer Radical Polymerization of Acrylate Monomers

An Acid Test: Facile SI‐ARGET‐ATRP of Methacrylic Acid

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