Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

Satoh, Kotaro; Kamigaito, Masami

doi:10.1021/cr900115u

Cited by 278 publications

(241 citation statements)

References 463 publications

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confidence: 99%

“…The effect of certain Lewis acids on the stereochemical composition of the macromolecules prepared via radical polymerization has been reported [17,[19][20][21]. The "stereospecific radical polymerization" term has been suggested by the Japanese scientists to describe such processes [20,21]. However, in view of the recently reported data on the effects of structurally diverse metal-containing compounds on the radical polymerization with the character of stereoregular, complex-, and/or coordination-radical behavior [8,17,18,[22][23][24], such processes rather should be regarded as metal-complex radical polymerization, since these processes are based on the complex formation between the metal compound with the macroradical and/or monomer, resulting in the polymer chain propagation vie the cyclic reaction complex [17,18].…”

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Iron compounds in controlled radical polymerization: Ferrocenes, (clathro)chelates, and porphyrins

Islamova

2016

Russ J Gen Chem

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Abstract-Experimental data on the application of metal complexes in radical polymerization of vinyl monomers collected over the recent 15 years have been analyzed and generalized. Special attention has been given to (un)substituted ferrocenes, macrocyclic (clathro)chelates, and iron porphyrinates as well as to the approaches to enhance their catalytic activity in controlled synthesis of macromolecules. The mentioned systems have been compared with each other as well as with selected complexes of other transition metals. It has been shown that the electronic and spatial structures of the metal complexes are related to their efficiency in the radical polymerization reactions. Keywords: controlled radical polymerization, metallocene, (clathro)chelate, metal porphyrinate, catalytic/ initiating system Application of metal complexes opens broad prospects to control the polymerization processe and to prepare polymer materials with improved physicochemical properties. The metal complex catalysis has become of special importance in the field of controlled radical polymerization over the recent 15 years.The term "controlled radical polymerization" is generally referred to "living" or "pseudo-living" radical polymerization; its mechanism, irrespectively of the type of the catalysts/mediators applied (metal complexes [1-11], nitroxyl compounds [12-14], thioesters [15,16], etc.) is based on minimization of the probability of the interaction between the propagating radicals, resulting in the irreversible chain termination. This allows for control of molecular parameters of the prepared polymers, in particular, reduction of the polydispersity coefficient down to M w /M n = 1.1, achieving the linear behavior of the number-average molecular mass (M n ) as function of the conversion, elimination of the undesirable gel effect, and preparation of block copolymers.Atom Transfer Radical Polymerization (ATRP) [1], Transition Metal-Catalyzed Living Radical Polymerization [7], and Organometallic Mediated Radical Polymerization (OMRP) [11] are among the types of controlled radical polymerization. The first approach is based on the use of halides of organic complexes of transition metals, leading to the formation of labile terminal carbon-halogen bond (P n -Hlg). Under certain conditions, this bond is capable of dissociation to regenerate the initial or new active radical further propagating the polymer chain (Scheme 1).Here P n · stands for the propagating macroradical, М is the vinyl monomer, HlgMt x+1 /L is the metal complex halide (with L as the organic ligand), Mt is the transition metal, and k p is the rate constant of the chain propagation.The second of the listed methods uses stable radical organometallic species or diamagnetic transition metal complexes forming the carbon-metal bond P n -Mt as the regulators of the polymer chain growth [11] (Scheme 2).Due to the similarity of these two approaches their simultaneous operation is often assumed [11].Besides "living" radical polymerization, complexand/or coordination-radical polymeri...

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Iron compounds in controlled radical polymerization: Ferrocenes, (clathro)chelates, and porphyrins

Islamova

2016

Russ J Gen Chem

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“…38,[40][41][42] As for the metal-catalyzed living radical polymerization, we first examined the combination of the dinuclear iron(I) complex [Fe 2 Cp 2 (CO) 4 ] and lanthanide triflate (for example, Y(OTf) 3 and Yb(OTf) 3 ) to control the molecular weight and the tacticity, respectively, in the radical polymerization of acrylamide derivatives (Figure 15). 115 The low oxidation state iron(I) complex, which is one of the most active and versatile metal catalysts, induced an efficient and rather faster polymerization of N,N-dimethylacrylamide (DMAM) in the presence of Y(OTf) 3 than in its absence.…”

Section: Stereospecific Living Radical Polymerizationmentioning

confidence: 99%

“…Although the stereochemical control of radical polymerization has been achieved for specially designed monomers such as bulky monomers, in special confined spaces such as meso-pores, or in the solid state, such as monomer crystals, it is rather limited to these special cases and cannot be used for common vinyl monomers. 38 However, over the past 10 years, there have been significant developments in controlling steric structures during the radical polymerization of the common polar vinyl monomers using bulky fluorinated alcohols as solvents or lanthanide triflates as Lewis acid additives, as discovered by Okamoto and co-workers ( Figure 3). 39 These acidic compounds can coordinate to the carbonyl groups of the polar monomers and around the growing chain ends to restrict the free rotation of the propagating radical species to induce the stereospecific propagation.…”

Section: Introductionmentioning

confidence: 99%

“…Another further control of radical polymerization is the dual control of the polymer molecular weight and tacticity, which have not yet been fully attained. 38,[40][41][42] This review covers recent developments in metal-catalyzed living radical polymerization, focusing on our research studies, including the metal-catalytic system, the precision synthesis of well-controlled polymers, and the simultaneous control of the molecular weight and tacticity using metal-catalyzed stereospecific living radical polymerizations. Although there has been great progress in other…”

Section: Introductionmentioning

confidence: 99%

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Recent developments in metal-catalyzed living radical polymerization

Kamigaito

2010

Polym J

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This review presents a short overview of recent developments in metal-catalyzed living radical polymerization, mainly focusing on our recent research studies related to the subject. Metal-catalyzed living radical polymerization or atom transfer radical polymerization, which was originally developed via evolution of the metal-catalyzed Kharasch or atom transfer radical addition to chain-growth polymerization via reversible activation, has now been widely developed in many aspects. The effective metal catalysts include various transition metals, such as ruthenium, copper, iron and nickel, and highly active and versatile catalytic systems have been developed by designing ligands, applying lower oxidation metal species and using additives to widen the scope of controllable monomers and to minimize the amount of metal catalysts and the residual metals in the products. The development of the initiating systems has enabled the synthesis of a wide variety of novel, well-defined polymers, including end-functionalized, block, graft and star polymers, but also more complicated polymers possessing multiple controlled structures. Furthermore, metal-catalyzed living radical polymerization has been judiciously combined with stereospecific radical polymerization based on the use of polar solvents or Lewis acid additives, resulting in the dual control of the molecular weight and the tacticity of the resulting polymers and enabling the preparation of stereoblock and stereogradient polymers. Keywords: block polymer; living radical polymerization; precision polymer synthesis; transition metal catalyst; star polymer; stereospecific polymerization INTRODUCTIONSince the discovery of metal-catalyzed living radical polymerization or atom transfer radical polymerization (ATRP), there have been many developments in this research area, including active and versatile metal catalytic systems; the scope of controllable monomers; well-defined polymers with various controlled architectures; hybridization of the controlled polymers with inorganic, metal and biomolecular compounds; and attempts or real applications to a variety of industrial materials. 1-17 Besides these metal catalytic systems, there have also been substantial developments in various living radical polymerizations, such as nitroxide-mediated polymerizations, reversible addition fragmentation chain-transfer polymerizations and others, and in all of these, there are characteristic features of the mechanisms and components. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] The metal-catalyzed living radical polymerization was originally discovered via evolution of the metal-catalyzed Kharasch or atom transfer radical addition reaction 35 to the chain-growth polymerization of vinyl monomers (Figure 1). 1 The initiating system generally consists of a transition metal complex in a lower oxidation state and an organic halide, in which the carbon-halogen bond of the halogen compound is activated by the metal catalyst to generate the carbon radical species upon a one-e...

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Fluorinated Organic Polymers for Cancer Drug Delivery

Xin,

Lu,

Cao

et al. 2024

Advanced Materials

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In the realm of cancer therapy, the spotlight is on nanoscale pharmaceutical delivery systems, especially polymer‐based nanoparticles, for their enhanced drug dissolution, extended presence in the bloodstream, and precision targeting achieved via surface engineering. Leveraging the amplified permeation and retention phenomenon, these systems concentrate therapeutic agents within tumor tissues. Nonetheless, the hurdles of systemic toxicity, biological barriers, and compatibility with living systems persist. Fluorinated polymers, distinguished by their chemical idiosyncrasies, are poised for extensive biomedical applications, notably in stabilizing drug metabolism, augmenting lipophilicity, and optimizing bioavailability. Material science heralds the advent of fluorinated polymers that, by integrating fluorine atoms, unveil a suite of drug delivery merits: the hydrophobic traits of fluorinated alkyl chains ward off lipid or protein disruption, the carbon‐fluorine bond's stability extends the drug's lifecycle in the system, and a lower alkalinity coupled with a diminished ionic charge bolsters the drug's ability to traverse cellular membranes. This comprehensive review delves into the utilization of fluorinated polymers for oncological pharmacotherapy, elucidating their molecular architecture, synthetic pathways, and functional attributes, alongside an exploration of their empirical strengths and the quandaries they encounter in both experimental and clinical settings.This article is protected by copyright. All rights reserved

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Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

Cited by 278 publications

References 463 publications

Iron compounds in controlled radical polymerization: Ferrocenes, (clathro)chelates, and porphyrins

Iron compounds in controlled radical polymerization: Ferrocenes, (clathro)chelates, and porphyrins

Recent developments in metal-catalyzed living radical polymerization

Fluorinated Organic Polymers for Cancer Drug Delivery

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