Stereospecific living radical polymerization for simultaneous control of molecular weight and tacticity

Kamigaito, Masami; Satoh, Kotaro

doi:10.1002/pola.21688

Cited by 52 publications

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“…It has been demonstrated that certain Lewis acids of rare earth elements [in particular, lanthanide triflates like Y(OTf) 3 and Yb(OTf) 3 ] increase the content of iso structures in poly-N-isopropylamide from 44 to 66%. Fluorinated alcohols in combination with ruthenium complexes enhanced syndiotacticity of poly(methyl methacrylate) prepared at 0°С to 77% [19,51,52].…”

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“…This has been achieved by simultaneous addition of the Lewis acid (affecting the microstructure of the produced polymer) and the agent producing the "living" polymerization to the reaction mixture [52]. However, the Lewis acid facilitates the stereospecific growth of the polymer chain but simultaneously suppresses the effect of the second component, the product polydispersity reaching in certain cases M w /M n = 3.2.…”

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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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“…This material is typically synthesized by living anionic polymerization; stereospecific PMMA synthesized from controlled/ living radical polymerization has not been used previously in stereocomplexation studies. In this study, we utilized a novel syndiotactic (st-)PMMA star polymer synthesized by stereospecific living radical polymerization (SLRP) [15] and investigated its stereocomplexation behavior with linear isotactic (it-)PMMA. The macromolecular assembly of various nanoto-macroscale structures from a single pair of complementary polymers through helix formation has not been reported previously.…”

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Nano‐to‐Macroscale Poly(methyl methacrylate) Stereocomplex Assemblies

et al. 2009

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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%

“…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…”

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confidence: 99%

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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Stereospecific living radical polymerization for simultaneous control of molecular weight and tacticity

Cited by 52 publications

References 60 publications

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

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

Nano‐to‐Macroscale Poly(methyl methacrylate) Stereocomplex Assemblies

Recent developments in metal-catalyzed living radical polymerization

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