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In a brief review, the main trends in the modern development of the concept of controlled radical polymerization were considered and illustrated by specific examples. The prospects for applying the methodology of controlled synthesis of macromolecular structures, as well as for obtaining industrially significant and high-tech polymers, including precursors for the production of carbon fiber and other popular polymer materials and composites, were analyzed. Particular emphasis was placed on the use of photocatalysis and nature-like technologies in the controlled synthesis of polymers. [ABSTRACT FROM AUTHOR]

The influence of the structure of high-molecular-weight alkoxyamines (obtained in situ from C-phenyl-N-tert-butylnitrone and 2-(benzylideneamino)-2-methyl-1-phenylpropanol-1-N-oxide) and their low-molecular-weight analogs on styrene polymerization in the temperature range 70—110 ° was analyzed. The controlled synthesis of polystyrene in the presence of low-molecular-weight alkoxyamines was revealed to occur most efficiently at 110 °. The use of high-molecular-weight alkoxyamines makes it possible to perform the controlled process under lower-temperature conditions (70—90 °), when the constant polymerization rate and linear increase in the molecular weight with conversion are observed, and the synthesis of polymers with fairly low polydispersity (Mw/Mn ~ 1.26) is also possible. The quantum chemical calculations showed that the energy of the C-ON bond in alkoxyamines is determined by the length of the chains at the nitroxide fragment rather than the structure of the substituents. It is found that the equilibrium dissociation constants of high-molecular-weight alkoxyamines are caused by both the structure of the nitroxide fragment and molecular weights. [ABSTRACT FROM AUTHOR]

The review considers modern methods for the synthesis of polyacrylonitrile as a precursor for the production of high-strength carbon fiber. Special emphasis was placed on using controlled radical polymerization techniques for the synthesis of a polyacrylonitrile precursor of a given molecular weight in organic solvents. [ABSTRACT FROM AUTHOR]

The influence of bis[4,6-di- tert-butyl- N-(2,6-dimethylphenyl)- o-iminobenzosemiquinonato]cobalt( ii) and 4,6-di- tert-butyl- N-(2,6-diisopropylphenyl)- o-iminobenzosemiquinonato]-[4,6-di- tert-butyl- N-(2,6-diisopropylphenyl)- o-amidophenolate]manganese( iii) on polymerization of methyl methacrylate and acrylonitrile in the presence of azobisisobutyronitrile (as a traditional radical initiator) and alkyl halides (used for initiation of controlled atom transfer radical polymerization process) was studied. The effect of the nature of the activating agents (amines) and the temperature conditions on the overall polymerization rate of the indicated monomers, as well as molecular weight characteristics of the synthesized polymers, were analyzed. The optimal conditions for the synthesis of polyacrylonitrile and poly(methyl methacrylate) with a relatively narrow molecular weight distribution were selected. [ABSTRACT FROM AUTHOR]

The effect of a number of quinoid compounds on methyl methacrylate polymerization initiated by azo-bis(isobutyronitrile) has been studied. It has been revealed that N-aryl- o-iminobenzoquinones, in contrast to o-benzoquinones, can provide radical polymerization of methyl methacrylate in controllable mode. The efficiency of the compounds as chain growth regulators has been found to depend on their composition and reaction conditions. It has been established that 4,6-di- tert-butyl- N-(2,6-diethylphenyl)- o-iminobenzoquinone and 4,6-di- tert-butyl- N-(2,6-diisopropylphenyl)- o-iminobenzoquinone under radical initiation conditions provide the synthesis of poly(methyl methacrylate) with wide-range molecular weight, retaining polydispersity indices about ~1.4-1.8 up to deep conversions. [ABSTRACT FROM AUTHOR]

Polymerization of methyl methacrylate and styrene in the presence of manganese cyclopentadienylcarbonyl complexes containing π-alkene (methyl methacrylate), vinylidene, and allenylidene ligands was investigated. It was found that metal complex ligand environment plays a key role in the initiation of the polymerization and in the regulation of the molecular weight characteristics of synthesized polymers. In particular, the manganese complexes with cumulenylidene ligands are capable to initiate spontaneously polymerization of vinyl monomers. The process of polymerization proceeds to high conversions (over 90%), and the resulting polymers are characterized by high values of molecular weight and relatively broad molecular weight distribution. [ABSTRACT FROM AUTHOR]

An additive based on stearyl methacrylate-vinyl acetate copolymer was synthesized by the method of controlled atom transfer radical polymerization. The additive simultaneously improves the low-temperature properties of hydrotreated diesel fuels and enhances their resistance to thermal oxidation to meet the European quality standards. Comparative analysis of the effect exerted on the characteristics of environmentally clean diesel fuel by the synthesized additive and Dodiflow commercial depressor additive was made, and the negative effect of the latter on the thermo oxidative stability of diesel fuel was revealed of the fuel to thermal oxidation was revealed. [ABSTRACT FROM AUTHOR]

Specific features of the (co)polymerization of acrylonitrile in the presence of a catalytic system based on zero-valent copper and 2,2-bipyridyl in various solvents was studied. It is shown that these systems can be successfully used in the presence of halogen-containing initiators to obtain homo- and copolymers of acrylonitrile with dimethyl itaconate and methyl acrylate in the controlled mode. It was found that introduction of comonomers (methyl acrylate and dimethyl itaconate) in low concentrations has no effect on parameters of the acrylonitrile polymerization process, but strongly affects some properties and characteristics of samples being synthesized. [ABSTRACT FROM AUTHOR]

Using polymerization of a series of acrylic monomers of various structure in the presence of ruthenium complexes as an example, it was shown that introduction of amines into the polymerization system allows to overcome one of the significant drawbacks of the controlled polymer synthesis under the radical initiation conditions, connected with the low rate of the polymerization. The influence of the amine nature on the peculiarities of the controlled polymer synthesis in the presence of ruthenacarboranes has been studied and amine was found to act as a reducing agent converting ruthenium in a complex to the lowest oxidation state and regenerating the true polymerization catalyst. [ABSTRACT FROM AUTHOR]

Published data on controlled synthesis of polyvinyl chloride and of copolymers of vinyl chloride with other monomers under the conditions of radical initiation and coordination catalysis are analyzed. Prospects for using the known methods for controlled synthesis of macromolecules to obtain vinyl chloride homo- and copolymers under the conditions close to those of industrial processes are evaluated. Particular attention is paid to the use of metal complexes for preparing vinyl chloride based (co)polymers with preset values of the molecular mass and polydispersity in the living chain mode by the mechanism of atom transfer radical polymerization. The majority of papers analyzed in the review have been published in the past decade. [ABSTRACT FROM AUTHOR]

The effect of tin( IV) monocathecholate 36CatSnR• nTHF (36Cat is 3,6-di- tert-butylcatehol dianion; R = Me, Et, Ph, or Cl; n = 1 and 2) on the radical polymerization of methyl methacrylate and {itn}-butyl methacrylate was studied. The role of the complexes in the synthesis of the corresponding polymers is mainly determined by the structure of tin o-semiquinone derivatives formed directly in the polymerization process. Tin( IV) monocatecholates can control the synthesis of polymers via the mechanism of reversible inhibition and, in certain cases, exert an accelerating effect on the polymerization of methacrylic monomers like Lewis acids. [ABSTRACT FROM AUTHOR]

Radical polymerization of methyl methacrylate was studied in the presence of initiating systems based on bis[4,6-di- tert-butyl- N-(2,6-dimethylphenyl)- o-iminobenzosemiquinono]-cobalt(II) and hydrocarbon halo derivatives of different structure. The introduction of amines in the polymerizing system was found to lead to a significant increase in the polymerization rate. The polymerization proceeds via the atom transfer mechanism, which was confirmed by detection of ω-terminal chlorine atoms in the macromolecules by NMR, the linear dependence of the polymer molecular weight on conversion of monomer, and the synthesis of block-copolymers. [ABSTRACT FROM AUTHOR]

Specific features of radical polymerization of vinyl chloride in the presence of nitroxyl radicals of the imidazoline series (2-methyl-2,3-diphenyl-1,4-diazaspiro[4,5]dec-3-ene-1-oxyl, 2,2,5,5-tetramethyl-4-phenyl-2,5-dihydroimidazole-1-oxyl, 2,2,5-trimethyl-4,5-diphenyl-2,5-dihydroimidazole-1-oxyl) were studied. The possibility of preparing vinyl chloride-styrene block copolymers in the presence of these nitroxyl radicals was demonstrated, suggesting the occurrence of the polymerization by the reversible inhibition mechanism. The molecular-mass characteristics and the glass transition points of the synthesized samples were determined. [ABSTRACT FROM AUTHOR]

Characteristic features of synthesis of various polymers with participation of the tin complex imSQSnBuCl, where imSQ is the 4,6-di- tert-butyl- N-(2,6-diisopropylphenyl)- o-iminobenzoquinone radical anion, were studied. It was shown that for a number of monomers, this complex acts as an iniferter, i.e., it can not only initiate the polymerization, but can also regulate the chain growth of macromolecules. The effect of the conditions of the process on the possibility of obtaining macromolecular products with a narrow polydispersity was estimated. [ABSTRACT FROM AUTHOR]

It is shown that a cyclopentadienyl dicarbonyl iron dimer [CpFe(CO)2]2 in combination with an organohalogen compound is an effective initiator/regulator of the polymerisation of vinyl chloride at temperatures of 50- 70°C. The molecular weight characteristics, composition, and certain physicochemical properties of homo- and copolymers synthesised on the basis of vinyl chloride in the presence of the iron complex were investigated. [ABSTRACT FROM AUTHOR]

The ruthenacarborane complexes of the exo-nido- and closo-structure, namely, diamagnetic exo-nido-5,6,10-[RuCl(PPh)]-5,6,10-(μ-H)-10-H-7,8-(CH)-7,8-CBH, 3,3-[PhP(CH)PPh]-3-H-3-Cl- closo-3,1,2-RuCBH ( n = 4, 5), paramagnetic 3,3-[PhP(CH)PPh]-3-Cl- closo-3,1,2-RuCBH ( n = 2-5), and their some ortho-phenylenecycloboronated derivatives, were studied by cyclic voltammetry. All chelate closo-complexes are characterized by reversible redox transitions, while the exo-nido-complex is liable to irreversible oxidation. Shortening of the methylene link in the diphosphine ligand of closo-ruthenacarboranes and/or the introduction of ortho-phenylenecycloboronated moieties and methyl substituents to the carbon atoms of the {CB} ligand lead to a decrease in the redox potential and electron density redistribution to the metal atom. A comparison of the experimental results on methyl methacrylate polymerization in the presence of the catalytic systems based on the studied metallacarboranes with the data on their electrochemical characteristics suggests that the efficiency of using the ruthenium complexes as catalysts is mainly determined by steric factors. [ABSTRACT FROM AUTHOR]

The article discusses the study which reports a method for conducting controlled polymerization of methyl methacrylate (MMA) media with the use of chlorine-containing tin(IV) o-iminosemiquinone derivatives. The study used the gel permeation chromatography (GPC) to determine the molecular-weight characteristics of the polymers. Results show that main-group metal complexes with redox-active ligands are prone to elimination reactions and alkyl addition.

Novel catalytic systems were proposed for controlled radical polymerization of vinyl monomers. These systems are based on the paramagnetic (17-electron) closo-complex, namely, 3,3-(dppb)-3-Cl- closo-3,1,2-RuCBH ( 1, dppb is 1,4-bis(diphenylphosphino)butane) and its mono( P-phenylene)- and di( P,P- ortho-phenylene)cycloboronated derivatives, namely, [Figure not available: see fulltext.] (R = H, n = 10 ( 2); R = Me, n = 8 ( 3)) and [Figure not available: see fulltext.] ( 4). With the polymerization of methyl methacrylate as an example, the effect of the steric hindrances in complexes 1- 4 on the synthesis and molecular-weight characteristics of the resulting polymers was analyzed. In the presence of aliphatic amines, the polymerization rate increases substantially and the catalyst concentration can be lowered without losing control of the process. The structure of 17-electron complex 3 in the solid state and its paramagnetic nature were confirmed by X-ray diffraction and ESR spectroscopy. [ABSTRACT FROM AUTHOR]

Polymerization of methyl methacrylate and styrene in the presence of manganese cyclopentadienyl carbonyl-olefin complexes, with styrene and methyl methacrylate as olefins, was studied. The molecular-weight distribution of the polymers obtained was examined. [ABSTRACT FROM AUTHOR]

The main features of the radical polymerization of styrene in the presence of germanium(IV) and tin(IV) bis-catecholate complexes were studied in the temperature range 70-110 °C. Depending on the initial composition and structure, as well as on the reaction conditions, the complexes used can play the role of inhibitors or regulators directing the polymerization process. The ESR data in the styrene medium showed formation of germanium and tin o-semiquinolate derivatives, that indicates a direct involvement of the organoelement additives into the propagation step. The polymers synthesized in the presence of the bis-catecholate complexes of the IV group elements can be used as macroinitiators of styrene polymerization. [ABSTRACT FROM AUTHOR]

Radical polymerization of styrene in the presence of 2,2,4,5,5-pentamethyl-2,5-dihydro- Imidazol-1-oxyl, 2,2-diethyl-4,5,5-trimethyl-2,5-dihydroimidazol-1-oxyl, 2,2,5,5-tetramethyl- 4-phenyl-2,5-dihydroimidazol-1-oxyl, 2,2,5-trimethyl-4,5-diphenyl-2,5-dihydroimidazol- 1-oxyl, and 2-methyl-2,3-diphenyl-1,4-diazaspiro[4.5]deca-3-en-1-oxyl was studied. Effect of substituents in the nitroxyl radical and the nature of initiator on the features of 'pseudoliving' polymerization and the molecular-weight characteristics of polystyrene synthesized were considered. Nitroxyl radicals of imidazoline series, like TEMPO and its derivatives, allow one to regulate polymerization of styrene and obtain polymers with relatively low values of polydispersity index. [ABSTRACT FROM AUTHOR]

Specific features of homo- and copolymerization of styrene and methyl methacrylate in the presence of the catalytic system NiBr2dppe/PhI/Zn were studied. [ABSTRACT FROM AUTHOR]

The NiBr2(PPh3)2/Zn catalytic system in combination with the PhI initiator ensures methyl methacrylate polymerization in a wide temperature range. The polymer yield is determined by the ligand environment of the nickel atom, the reaction temperature, and the ratio of the components of the catalytic system. An analysis of the macrokinetic relationships and of the molecular-weight characteristics of the products indicates that polymerization occurs in a controlled regime. [ABSTRACT FROM AUTHOR]