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The features of radical polymerization of methyl methacrylate involving phenazine as photocatalyst, under UV irradiation, have been investigated. It has been found that the phenazine-based compositions allow initiation of the methyl methacrylate polymerization and, in certain cases, performing it in a controlled regime. It has been shown that it is possible to prepare poly(methyl methacrylate) over sufficiently wide range of molecular mass by adjusting the composition of the phenazine + organobromine compound + tertiary amine catalytic system, the obtained polymer being prone to further modification via block copolymerization. A specific feature of the suggested catalytic compositions is the possibility of the polymer synthesis to high conversion using a low concentration of the catalyst and without prior degassing of the reaction mixture. [ABSTRACT FROM AUTHOR]

Novel catalytic systems based on complexes of copper(II) bromide with polydentate nitrogen-containing ligands, tris[(2-pyridyl)methyl]amine and tris[(2-dimethylamino)ethyl]amine, and salts of organic acids (Rochelle salt, sodium oxalate, sodium lactate, and sodium pyruvate) acting as catalyst regenerating agents have been developed for the radical polymerization of acrylonitrile. It has been shown that the polymerization of acrylonitrile carried out in the presence of these systems and halogen-containing initiators occurs by the atom transfer mechanism, affording polymers with target molecular weight values. Effect of the nature of reducing agent and initiator on the process of polymerization and the degree of control over molecular weight characteristics of the resulting samples has been studied. It has been found that Rochelle salt and sodium oxalate are the most efficient reducing agents allowing for a high rate of polymerization while maintaining control over the process. [ABSTRACT FROM AUTHOR]

Features of the polymerization of methyl methacrylate and a number of other (meth)acrylate monomers in the presence of catalytic systems based on phenazine dyes (Neutral Red and Safranin Т) under visible light irradiation are investigated. It is shown that amines of various structure as well as air oxygen affect the kinetic features of polymerization and the molecular weight characteristics of polymers. It is found that polymerization may proceed in the controlled mode up to high conversions at room temperature and a low photocatalyst concentration, among them without preliminary degassing of the reaction medium. [ABSTRACT FROM AUTHOR]

Using methyl methacrylate polymerization as an example, the features of polymer synthesis in the presence of the catalytic system [methylene blue + ethyl 2-bromoisobutyrate] at room temperature under visible light irradiation are investigated. The effect of polymerization conditions, including the light irradiation wavelength and various structure activators, on the monomer conversion and molecular weight characteristics of polymers is estimated. It is shown that polymerization can proceed in the controlled mode under mild temperature conditions according to the atom transfer mechanism (Metal Free Atom Transfer Radical Polymerization) to high conversions at low photocatalyst concentrations. [ABSTRACT FROM AUTHOR]

The capacity of the coupling reactions of polystyrene bearing an ω-terminal bromine group in the presence of various nitrones and nitroso compounds has been disclosed. As exemplified by the coupling using С-phenyl-N-tert-butylnitrone, acetonitrile and tetrahydrofuran have been found the best solvents of the probed series (toluene, ethyl acetate, benzene, acetonitrile, and tetrahydrofuran). The said solvents have revealed the strongest coordination ability towards the catalytical system based on copper(I) bromide and have afforded high coupling degree (above 90%) preserving low polydispersity of the synthesized samples. It has been shown that the nitroso compounds involved in the coupling with styrene favor the formation of terminal nitroxyl fragments. In contrast to nitroso compounds, the nitrones have afforded symmetrical high-molecular alkoxyamines bearing a nitroxyl fragment in the middle of the polymer chain. [ABSTRACT FROM AUTHOR]

The effect of conjugated dinitrones N,N-dimethylglyoxaldinitrone, N,N-di-tert-butylglyoxaldinitrone, and N,N-diphenylglyoxaldinitrone on the radical polymerization of styrene initiated by azobis(isobutyronitrile) is studied. It is found that, during the polymerization of styrene at temperatures below 90°C, chains terminate on the studied nitrones to generate high molecular weight nitroxide radicals. The regularities of polystyrene synthesis in the presence of conjugated nitrones at 130°C (the first reaction order with respect to the monomer over the entire conversion range, a linear increase in molecular weight with conversion, and postpolymerization) indicate that the polymerization of styrene can be implemented under reversible inhibition conditions in the high temperature regime. It is shown that the acceptance and specific features of styrene polymerization mediated by nitroxide radicals formed in situ are directly related to the initial structure of dinitrones. For example, the presence of conjugation between phenyl and nitronyl groups in diphenyl dinitrone leads to a decrease in its accepting ability, lowering the effectiveness of high molecular weight nitroxides as polymerization regulators in the high temperature mode. Using the methods of static and dynamic light scattering, the hydrodynamic sizes of macromolecules are estimated and the form factor Rg/Rh of a linear polymer and polymers synthesized with the participation of dinitrones is calculated. [ABSTRACT FROM AUTHOR]

The controlled synthesis of poly(stearyl methacrylate) and stearyl methacrylate–acrylonitrile copolymers is conducted using a catalytic system consisting of copper(I) bromide, tris[(2-pyridyl)methyl]amine as a ligand, and isopropylamine as an activating agent. Effects of activator concentration and monomer mixture composition on the molecular-weight characteristics of the (co)polymers are estimated. It is shown that the products of synthesis may be used as depressor additives lowering the cloud point, pour point, and cold filter plugging point of diesel fuel. [ABSTRACT FROM AUTHOR]

Features of radical polymerization of several vinyl monomers in the presence of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone were studied. This compound was found to have an effect on the kinetic regularities of the synthesis of polymers at different temperatures and their molecular weight characteristics. Optimum conditions for the preparation of corresponding polymers and block copolymers involving 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone in a wide range of molecular weights and compositions were determined. [ABSTRACT FROM AUTHOR]

New regulators of radical polymerization of methyl methacrylate based on N-(aryl)- o-iminoquinones of various structures are proposed. It is shown that samples of polymethylmethacrylate with the participation of N-(aryl)- o-iminobenzoquinones could be used as macroinitiators of polymerization. Optimal conditions to synthesize polymers in the presence of o-iminobenzoquinones are determined, which make it possible to obtain polymethylmethacrylate with a polydispersity coefficient of no more than 1.5 on deep conversions during bulk polymerization. [ABSTRACT FROM AUTHOR]

The polymerization of acrylonitrile in the presence of catalytic systems based on copper(I) bromide, tris(2-pyridylmethyl)amine, and different reducing/activating agents is studied. It is found that the polymerization is controlled and that the activating agent is regenerated by a single-electron transfer. Moreover, the polymerization leads to the formation of polymers with high molecular weight and relatively narrow molecular-weight distribution. It is found that glucose and ascorbic acid are the most efficient among the studied activating agents in terms of the polymerization rate and the control over the molecular-weight characteristics of synthesized polymers. [ABSTRACT FROM AUTHOR]

The radical polymerization of isobornyl acrylate, isobornyl methacrylate, and tert-butyl methacrylate under conditions of catalysis by ruthenium compounds is studied. It is found that the catalytic system based on the carborane complex of ruthenium 3,3-{[1,1-diphenyl-6-phenyl-6-(6,8-( o-phenylene))]-1,6-diphosphahexane}-3-chloro- closo-3,1,2-dicarbollyl ruthenium and isopropylamine makes it possible to conduct the controlled free-radical polymerization of the mentioned monomers via the Atom Tranfer Radical Polymerization mechanism. The molecular weights of the polymers linearly increase, while their polydispersity coefficients linearly decrease during the process. Block copolymers are synthesized on the basis of the above monomers, and the molecular-weight characteristics and glass-transition temperatures of these copolymers are measured. [ABSTRACT FROM AUTHOR]

The influence of bis[4,6-di- tert-butyl- N-(2,6-dimethylphenyl)- o-iminobenzosemiquinonato]cobalt (II) on the radical polymerization of methyl methacrylate and styrene under the conditions of radical initiation by azo-bis-isobutyric acid dinitrile in the temperature range 70-90°C has been studied. The use of the cobalt complex containing redox-oxidized ligands leads to the suppression of autoacceleration of the polymerization of methyl methacrylate and to a linear increase in the molecular masses of the polymers with conversion. In the case of styrene polymerization, the control over the kinetics of the process and molecular weight characteristics of the polymers synthesized in the presence of the cobalt iminobenzosemiquinone complex is less pronounced. [ABSTRACT FROM AUTHOR]

Catalytic systems based on carborane complexes of ruthenium with long-chain diphosphine ligands, such as 1,4-bis(diphenylphosphino)butane and 1,5-bis(diphenylphosphino)pentane, are prepared for the controlled radical polymerization of methyl methacrylate. It is found that the used metallacarboranes can catalyze polymerization initiated by both carbon tetrachloride and 2,2′-azo-bis(isobutyronitrile). It is shown that closo-ruthenacarborane with 1,5-bis(diphenylphosphino)pentane 3,3-[PPh(CH)PPh]-3-Cl-3,1,2- closo-RuCBH and its o-phenylenecycloborated derivatives make it possible to conduct polymerization at higher rates than those attained with the use of previously synthesized complexes based on diphosphines with a smaller length of the hydrocarbon fragment. The relationship between the redox potential of the complex and the efficiency of control over molecular-mass characteristics of the polymers is analyzed. Experiments reveal that the addition of small amounts of aliphatic amines causes a considerable increase in the rate of polymerization and leads to a decrease in the concentration of the catalyst with retention of a high degree of control over the process. [ABSTRACT FROM AUTHOR]

It was shown that mono- and binuclear carbonyl complexes combined with carbon tetrachloride were effective initiators of the radical polymerization of acrylonitrile. The mechanism of initiation of acrylonitrile polymerization in the presence of the investigated iron complexes was studied. [ABSTRACT FROM AUTHOR]

The radical polymerization of methyl methacrylate catalyzed by systems based on paramagnetic closo-ruthenacarboranes with diphosphine ligands is studied. Effects of the structure of metallocomplex catalysts on the rate of polymerization and the molecular-mass characteristics of the polymers are investigated. It is shown that the addition of amines to the reaction solution makes it possible to reduce the concentration of metallacarborane catalysts to hundredths of a percent, while control over the polymerization process remains at a high level. [ABSTRACT FROM AUTHOR]

The polymerization of styrene, methyl methacrylate, and vinyl chloride catalyzed by η-cyclopentadienyl-η-styrenedicarbonylmanganese is studied. It is shown that the cyclopentadienyl complex of manganese containing the monomer ligand (styrene) in the coordination sphere can initiate the radical polymerization of vinyl monomers in a mild temperature range. On the basis of the experimental data and the quantum-chemical simulation of the initial stages of the process, schemes describing the initiation of polymerization under the action of the complex under study and the binary initiating system containing carbon tetrachloride are advanced. In the latter case, additional acceleration of the reaction is related to the interaction of carbon tetrachloride with the triplet form of the manganese complex that yields trichloromethyl radicals initiating polymerization. [ABSTRACT FROM AUTHOR]

The polymerization of methyl methacrylate initiated by a catalytic system based on the complex CH=CHCHN(PPh)NiBr containing a bidentate phosphine ligand in the coordination sphere of nickel is studied. The activities of this system and of the catalytic system based on NiBr(PPh) with a monodentate ligand at the nickel atom in the synthesis of PMMA are compared. A scheme of polymerization catalyzed by the CH=CHCHN(PPh))NiBr system is advanced. [ABSTRACT FROM AUTHOR]

The regularities of methyl methacrylate and styrene (co)polymerization in the presence of catalytic systems based on a Ni(II) complex combined with zinc and an aryl halide have been studied. The effects of temperature and catalytic system components on conversion are established. The molecular masses of the polymers linearly increase with monomer conversion, thus suggesting the controlled character of the polymerization. Reactivity ratios are calculated for methyl methacrylate-styrene copolymerization ( r MMA = 0.45, r styrene = 1.70) in the presence of NiBr2(PPh3)2/Zn/PhI. The rate of copolymerization is shown to decrease with an increase in methyl methacrylate concentration. The scheme of the process is proposed based on an analysis of the experimental and literature data. [ABSTRACT FROM AUTHOR]

The synthesis of PS in the presence of diethyl(3,6-di- tert-butylcatecholato)tin(IV) tetrahydrofuranate and diphenyl(3,6-di- tert-butylcatecholato)tin(IV) tetrahydrofuranate has been studied. It has been found that such tin catecholates can act as chain length regulators in the polymerization of styrene and ensure a linear increase in molecular mass with conversion. Using the macroinitiators obtained in the presence of diphenyl(3,6-di- tert-butylcatecholato)tin(IV) tetrahydrofuranate, the postpolymerization of styrene has been carried out. [ABSTRACT FROM AUTHOR]

The polymerization of styrene and methyl methacrylate in the presence of 2,2-diethyl-4,5,5-trimethyl- 2,5-dihydroimidazol-1-oxyl has been studied. It has been demonstrated that the nitroxyl radical makes it possible to control chain propagation in the polymerization of styrene and to synthesize polymers with relatively low polydispersity coefficients (<1.4). The polymerization of methyl methacrylate in the controlled mode cannot be performed because of the occurrence of a side reaction related to hydrogen atom transfer. [ABSTRACT FROM AUTHOR]

2,2,5,5-Tetramethyl-4-phenyl-2,5-dihydroimidazole-1-oxyl and 2,2,5,5-tetramethyl-4-phenyl-2,5-dihydroimidazole-3-oxide-1-oxyl have been used as regulators of chain growth in the free-radical polymerization of styrene. It has been shown that the compounds of the dihydroimidazole series function as new living polymerization agents and allow the synthesis of polymers with low polydispersity coefficients and desired molecular masses. [ABSTRACT FROM AUTHOR]