Targeted synthesis of homo-and copolymers of propylene in liquid propylene initiated by highly efficient homogenous metallocene catalysts

Studies devoted to the homo-and copolymerization of propylene with ethylene and higher olefins (1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene) in liquid propylene under the action of homogeneous metallocene catalysts of various types are surveyed in brief. The main kinetic features of the processes and the properties of the polymers are discussed. The optimal conditions for the highly efficient syntheses of isotactic, syndiotactic, hemiisotactic, and stereoblock PPs are described. It is shown that the combined cocatalyst—polymethylaluminoxane coupled with (i-Bu)₃Al—shows promise for the processes under consideration. Depending on the type of catalyst used, the copolymerization of propylene with ethylene yields copolymers with a block, random, or close to alternating distribution of comonomer units in a polymer chain. The copolymerization of propylene with higher olefins in the monomer bulk initiated by highly active sterically hindered isospecific catalytic systems shows an ideal character, and the reactivity ratios are r ₁ ≈ r ₂ ≈ 1; that is, the composition of the copolymer is equal to the composition of the monomer mixture at all comonomer ratios. It is demonstrated that the synthesis of homo-and copolymers of propylene in the monomer bulk in the presence of modern homogeneous catalysts is promising for highly efficient production of both traditional and new polymer materials with a unique combination of mechanical and thermal properties.