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Depressor additives based on stearyl methacrylate homopolymer and its copolymers with various monomers (butyl methacrylate, methacrylic acid esters of С10–С14 fraction, maleic anhydride) were synthesized in the presence of reversible addition–fragmentation chain-transfer agents allowing control of the molecular-weight characteristics of the polymers. The low-temperature properties of the diesel fuel containing additives based on the above polymers were evaluated. The copolymers exhibit the better depressor effect compared to the stearyl methacrylate homopolymer. Modification of the stearyl methacrylate–maleic anhydride copolymer with 1-octanol was performed. The modified additive well competes in performance with the modern commercial depressor-dispersing additives and can decrease the congealing point of hydrotreated diesel fuels by 20°С. [ABSTRACT FROM AUTHOR]

Polymers based on methacrylic monomers were synthesized using 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone. They can be used for the directed synthesis of linear block copolymers with various compositions in the wide range of molecular weights under conditions of the polymerization according to the mechanism of reversible inhibition. It has been demonstrated that a structure of monomer plays the key role in the synthesis of block copolymers with relatively low values of the polydispersity coefficient. The optimal conditions for the synthesis of linear block copolymers based on methacrylic structures monomers have been revealed. [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.

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]

The effects of amines on the activity of ruthenium catalysts in the controlled synthesis of poly(methyl methacrylate) are reported at 80°C. The introduction of tert-butylamine or triethylamine into the polymerization system raises the polymerization rate by 1–2 orders of magnitude without reducing the high degree of control over the chain propagation step. The “living” character of methyl methacrylate polymerization in the presence of ruthenacarboranes and amines is proved by the fact that, as the monomer conversion increases, the molecular weight of the resulting polymer increases linearly and the polydispersity index decreases. The polymer can serve as a macroinitiator for postpolymerization and block copolymer synthesis. [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]