Binary Copolymerization of p-Methylstyrene with Butadiene and Isoprene Catalyzed by Titanium Compounds Showing Different Stereoselectivity

The synthesis of p -methylstyrene–butadiene and p -methylstyrene–isoprene binary copolymers promoted by the titanium complexes Ti(η 5 -C 5 H 5 )-(κ 2 -MBMP)Cl ( 1 ) (MBMP = 2,2′-methylenebis(6- tert -butyl-4-methylphenoxo)) and chloro{1,4-dithiabutanediyl-2,2′-bis(4,6-di- tert -butylphenoxy)}titanium ( 2 ) activated by methylaluminoxane (MAO) is reported. Syndiotactic poly( p- methylstyrene)- co - cis -1,4-poly(butadiene) and syndiotactic poly( p- methylstyrene)- co - cis -1,4-polyisoprene were obtained using catalyst 1, whereas isotactic poly( p- methylstyrene)- co - trans -1,4-poly(butadiene) and isotactic poly( p- methylstyrene)- co - trans -1,4-polyisoprene were obtained using the catalyst 2 . 13 C NMR analysis of the copolymer microstructure allowed to assess the monomer block lengths and distribution in the polymer chain, revealing a blocky distribution of the two monomers along the polymer chain in the presence of the catalyst 1 and a random distribution with the catalyst 2 for both binary copolymers.