Copolymerization of 2-butene and ethylene with catalysts based on titanium and zirconium complexes

Abstract

The polymerization of 2-butene and its copolymerization with ethylene have been investigated using four kinds of dichlorobis(β-diketonato)titanium complexes, [ArN(CH2)3NAr]TiCl2 (Ar = 2,6-iPr2C6H3) and typical metallocene catalysts. The obtained copolymers display lower melting points than those produced of homopolyethylene under the same polymerization conditions. 13C NMR analysis indicates that 9.3 mol-% of 2-butene units were incorporated into the polymer chains with Ti(BFA)2Cl2-MAO as the catalyst system. With the trans-2-butene a higher copolymerization rate was observed than with cis-2-butene. A highly regioselective catalyst system for propene polymerization, [ArN(CH2)3NAr]TiCl2 complex using a mixture of triisobutylaluminium and Ph3CB(C6F5)4 as cocatalyst, was found to copolymerize a mixture of 1-butene and trans-2-butene with ethylene up to 3.1 mol-%. Monomer isomerization-polymerization proceeds with typical metallocene catalysts to produce copolymers consisting of ethylene and 1-butene.