E. V. Kolyakina

The production of polymeric materials is one of the fast-growing sectors in the chemical industry. Improving methods for synthesizing high-molecular compounds and studying their physicochemical characteristics are important tasks of synthetic chemistry. Radical polymerization is currently the main method for producing polymeric materials. Its advantages involve simplicity and low cost, along with the possibility of obtaining a wide range of polymeric materials. The results of measuring the dielectric parameters of various high-molecular compounds (polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, poly(glycidyl methacrylate)) in the frequency range of 100–200 GHz (refractive index and dielectric loss tangent tgδ) are presented. The compounds under study were both those synthesized by radical polymerization with the participation of the conventional initiator, i.e., azobisisobutyric acid dinitrile, and commercial products. The absorption capacity of polymers at room temperature was compared. Polymers with the highest and lowest absorption capacity were determined. The dependence of tgδ on frequency for all the polymers under study is linear, with absorption in the polymers increasing with frequency. Poly(glycidyl methacrylate) exhibits the highest absorption among the studied macromolecules with tgδ being equal to 0.043 at 200 GHz. The minimum tgδ value of 0.0068 was found for polystyrene. For the polymers under study, the refractive index value varies in the range from 1.09 to 1.39. In addition, dielectric properties of the original vinyl monomers (styrene, vinyl acetate, glycidyl methacrylate) were studied. The results are of interest when developing approaches to obtaining polymeric materials with specified characteristics based on vinyl monomers by the method of radical polymerization.

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.

We studied the effect of bis[4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-ortho-iminobenzosemi-quinono]cobalt(II) on the kinetics of the bulk polymerization of methyl methacrylate at 70°C and on the molecular-weight characteristics of the polymer synthesized. The effective chain transfer constant in the polymerization of methyl methacrylate in the presence of the complex in benzene at 70°C was determined by the Mayo method and by linearizing the macromolecule chain length distribution. The constants obtained were compared with the same parameters available from the literature for a number of known chain-transfer agents, viz., dodecyl mercaptan and cobalt porphyrin and oxime complexes.