Copolymerization of Ethylene and α-Olefins with Bridged Metallocene/MAO

Copolymerization of ethylene and α-olefins via novel cyclohexylidene-bridged metallocenes [CH25C] (t-BuCp)2ZrCl2(I),[CH25C](t-BuCp)2TiCl2 (Ⅱ) activated with MAO. There exhibit the relationship between structural characteristics and the catalytic properties with behavior of polymers. And both catalyst I and II presented a comonomer effect in copolymerization activity by increasing the initial concentration of α-olefin (1-hexene, 1-octene). The melting points of the copolymers decreased with the increasing of comonomer, and the enthalpies of fusion decrease greatly due to the lower crystallinity. The selectivity of metallocene Ⅱ was bigger than metallocene I due to the larger reaction space of the metal center in metallocene I.