Homopolymerization of styrenic monomers and their copolymerization with ethylene using group 4 non-metallocene catalysts

摘要

Homopolymerization of styrenic monomers (St, p-Me-St, p-tBu-St, p-tBuO-St) and their copolymerization with ethylene, with the use of [((O2NN)-O- tBu2 ')ZrCl](2)(mu-O) (1) and ((O2NN)-O- tBu2 ')TiCl2 (2), where (O2NN)-O- tBu2 ' = Me2N(CH2)(2)N(CH2-2-O--3,5-tBu(2)-C6H2)(2), is explored in the presence of MMAO and (iBu)(3)Al/Ph3CB(C6F5)(4). The ethylene/styrenic monomers copolymerization with 1/MMAO produces exclusively copolymers with high activity and good comonomer incorporation whereas the other catalytic systems yield mixtures of copolymers and homopolymers. The use of p-alkyl styrene derivatives instead of styrene raises the catalytic activity, comonomer incorporation and molecular weights of the copolymers. Complex 2 exhibits higher activity in homopolymerization of styrenic monomers than 1 irrespective of the kind of the activator employed. A clear dependence is observed for the molecular weight and catalyst activity against the kind of the styrenic monomer. The obtained polymers were atactic and only the complex 2, when activated by MMAO, promoted the highly syndiospecific polymerization of p-Me-St and p-tBu-St. Poly(p-tBuO-St) exhibits fiber-forming properties.