Vol 65, No 4 (2023)

The features of ethylene polymerization in the presence of dichloridobis(salicylaldaryliminato)titanium(IV) complexes containing a 4-allyloxy-2,3,5,6-tetrafluorophenylimino group, namely, {2‑[(4-CH2=CH-CH2O)C6F4N=CH]-6-R1-4-R2-C6H2O}2TiCl2 (R1 = t-Bu, CMe2(Ph); R2 = H, Me, OMe, t-Bu, CMe2(Ph), Cl, Br) in the presence of methylalumoxane, have been studied. All the complexes exhibit high catalytic activity (27.8×106 гПЭ∙мольTi‐ 1∙МПаC2H4-1∙ч‐ 1)) in the temperature range of 10‒60°C and form powdered ultrahigh molecular weight polyethylene (UHMWPE) (M = (4.4–16.0) × 106 g/mol) with a low number of intermolecular entanglements. It has been shown that during polymerization, the complexes are immobilized on UHMWPE macromolecules.

Исследован процесс полимеризации L-лактида под действием органического катализатора 1,8-диазабицикло[5.4.0]ундец-7-ена. Определены частные порядки реакции по мономеру и катализатору, рассчитана константа скорости полимеризации. Синтезированы перспективные для применения в медицине линейные поли-L-лактиды со среднемассовой молекулярной массой от 29 × 10³ до 125 × 10³ и индексом полидисперсности не выше 1.25. Показана возможность использования комбинации органокатализатора и гидроксилсодержащих инициаторов для синтеза звездообразного полилактида и амфифильного сополимера полилактид–блок–полиэтиленоксид.

Submicron composite particles with the core/shell structure are synthesized by the seeded emulsion polymerization of a mixture of various acrylates in the presence of a redox initiation system. The diameter, morphology, and surface structure of particles as well as their ability to self-assemble into 3D ordered thin-film structures are studied by scanning electron microscopy, FTIR spectroscopy, thermogravimetry, and dynamic light scattering. It is shown that under the used experimental conditions particles with a shell thickness of 10‒35 nm are synthesized. The effect of shell composition (in particular, the alkyl chain length of acrylate comonomers) on the morphology and structure of the surface layer of the obtained composite particles is traced.

The influence of the substituents inductive effect and the proton-donor OH group in the substituted cyclocarbonates differing in the alkyl chain length on the activation barrier of their aminolysis reaction, which underlies the process of urethane formation without the participation of isocyanates, has been studied. Account for the solvent molecules has allowed quantitative interpretation of the process regularities. Kinetics of the model aminolysis reaction of a series of monomers in DMSO has been investigated.

The conditions to prepare luminescent acrylate polymers containing the organic dyad, molecule of which combines two different emitting fragments, hydroxyl-substituted 2,4,5–triarylimidazole and 8-azomethine-7-hydroxycoumarine moieties, via photocuring have been optimized. The effect of the nature of the photocured network acrylate polymers on luminescent properties of the dyad has been investigated. The prepared aliphatic network polymers have exhibited independent fluorescence of both molecule fragments, dependent on the excitation wavelength. At the same time, the aromatic network polymers and the aliphatic network polymers containing ether links have revealed only the imidazole fragment fluorescence. The fluorescence nature has been stronger dependent on the polymer repeat unit structure and the content of the aromatic fragments in the polymer matrix than on the presence of the hydroxyl groups in the polymer. It has been shown that the emission of the imidazole fragment of the dyad in the aliphatic network polymers depends on the internode distance and conditional polarity of the medium.

Polymerization of 5-vinyltetrazole under conditions of radical initiation in aqueous media in the presence of chitosan gave network graft copolymers, the structure of which is built from chitosan macromolecules crosslinked by chain fragments of poly(5-vinyltetrazole). It was determined that the polymerization is preceded by the formation of a saltlike product between chitosan macromolecules and vinyl monomer, which affects its polymerization activity. The obtained graft copolymers are prone to limited swelling in water to form pH-sensitive ampholytic hydrogels.