Butadiene polymerization with various half-titanocenes

The polymerizations of butadiene were performed with various half-titanocen es in combination with either modified methylalumoxane (MMAO) or (C6H5)(3)C B(C6F5)(4)/trialkylaluminum and the latter activator showed higher catalyst activities. The substitution of an alkyloxy group for a Cl atom in CpTiCl3 decreased activity and did not change the microstructure of polymers. CpTi Br3 and half-titanocenes with substituents on a Cp ring exhibited lower act ivities, but the microstructure of higher vinyl unit contents. The results of activity suggest cationic active species of Ti(+4). (C) 1999 Elsevier Sc ience B.V. All rights reserved.