In the description of multicenter ion-coordination polymerization of isoprene on the catalytic system GdCl3· n(i-C3Н7OH)‒Al(i-C4H9)3 the inverse kinetic task for the scheme of a process with slow initiation has been solved. The task of determining the number of active centers of polymerization was solved by deconvolution of experimental MWDs through superposition of Flory distributions. It has been shown that four types of active centers participate in polymerization, the kinetic difference of which in the process of formation of polymer fractions with their characteristic average molecular weights and the most probable MWD, is associated with their difference in the concentrations of pre-reaction catalytic centers and the rate constants of reactions occurring on them. For each type of active centers, partial conversions of monomer consumption and rate constants of initiation, chain propagation, and chain transfer to the monomer are determined.

Reliable NMR determination of the stereoisomeric composition of polyisoprene obtained in the presence of a catalyst based on a solvation complex of gadolinium chloride with isopropanol, activated with triisobutylaluminum, is possible only after thorough removal of traces of gadolinium compounds, which are strong relaxants in magnetic resonance imaging. In determination of the stereoisomeric composition of polyisoprene by Fourier IR spectroscopy, more reliable results are reached when plotting a separate baseline for each absorption band.

Lanthanide catalysts are used in the industrial production of stereoregular rubbers. It is believed that the activity of solvate complexes of lanthanide chlorides increases with decreasing size of their particles and increasing content of the solvating ligand. The kinetics of isoprene polymerization catalyzed by the isopropanol solvates of gadolinium chloride GdCl 3 · n ( i -PrOH), which were obtained by various methods (conventional mechanical stirring, hydrodynamic exposure, ultrasonic irradiation), was studied. A correlation between the particle size and composition of the solvate complex and the activity of the catalyst was found whatever the method the solvate complex was obtained. At the same time, the resulting data show that, at comparable particle size and composition of the complex, its activity in the polymerization of isoprene nevertheless depends on the method of synthesis. It was shown that the gadolinium catalysts exhibit the highest activity in isoprene polymerization, when the solvate complexes are subjected to hydrodynamic treatment after preliminary solvation for 4–8 h.

For butadiene polymerization with the multicenter catalyst TiCl 4 –Al( i -C 4 H 9 ) 3 the inverse kinetic task with identification of the kinetic scheme and determination of the kinetic parameters is solved. The preliminary experimental molecular weight distribution of polybutadiene macromolecules is approximated by the superposition of Flory distributions. Polymerization is modeled by the Monte Carlo method using a novel fast “inversion” algorithm that enables the time of calculations to be reduced by two orders of magnitude compared with the classical scheme of the method. It is shown that for identification of the kinetic scheme of diene polymerization in the presence of multicenter catalysts coincidence between the experimental and calculated dependences of monomer conversion on time and the dependences of average weights (or average degrees of polymerization) on polymerization time is insufficient. Coincidence between molecular weight distributions at all polymerization times is also required.

The disperse composition of trans-1,4-polyisoprene granules and supported titatium–magnesium catalyst particles in the ultrarapid polymerization of isoprene within 0.1–0.7 s is studied. It is shown that within this period the alteration of external and internal fragmentations occurs between two fractions of polymer granules that are formed by 0.1 s of polymerization and already contain significantly fragmented catalyst particles. The correlation between these processes and molecular mass characteristics of trans-1,4-polyisoprene is investigated. It is found that the external fragmentation is accompanied by a decrease in the average molecular masses of the polymer, while the internal fragmentation leads to formation of a higher molecular mass trans-1,4-polyisoprene. As a result, the fraction of polymer granules with a diameter of 7.5 μm is formed by 0.7 s of polymerization and replication to high conversions is developed on their basis.