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(η5-C5H5)-(κ2-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. 13C 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.