Study On Polymerization Of Isoprene Catalyzed By Late Transition Metal Co Complexes

In this paper,the structures of cobalt dichloride complexes catalyst with the 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridyl cobalt(Ⅱ)dichlorides as ligand were studied,and using them and cocatalyst,polymerization of isoprene was discussed.Using 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridyl cobalt(Ⅱ)dichlorides ligand as the main catalyst,isoprene was polymerized.The effect of co ligands and modification of alkyl aluminum catalytic system on polymerization of isoprene was studied.The results of IR and NMR showed that the polyisoprene contained cis-1,4 and 3,4 structure,lateral subgrade on primary catalyst ligand changes can have a greater impact on aggregate activity and the structure of the product.The change of cocatalyst can also affect the polymerization.The ethylaluminum sesquichloride is greater than diethylaluminum chloride,and structure of products were different.The products contained high cis-1,4 structure using ethylaluminum sesquichloride as cocatalyst,the content reached 95%.However,using diethylaluminum chloride as cocatalyst,the content of 3,4 structure of products can reached 30%.The polymerization conditions and other factors also effect polymerization activity and the structure of products obtained with the catalyst of 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridyl cobalt(Ⅱ)dichlorides ligand complexes based cobalt dichloride were studied.With the increasing of polymerization time,the conversion ratio and catalytic efficiency of catalyst(Ac)increased,intrinsic viscosity of polymers firstly increased and then decreased,and gel content increased.Monomer conversion ratio and catalyst efficiency increased with the rising of Al/Co and then decreased.The intrinsic viscosity of polymers first increased and then decreased with the increase of Al/Co and change significantly.At 20℃-50℃,the monomer conversion ratio and catalytic efficiency increased rapidly with the rising of temperature,and intrinsic viscosity of polymer and gel content increased with the rising of temperature.The effect of the polymerization solvent polymerization process was studied.The polymerization activity using toluene as solvent is greater than when the solvent is n-heptane and product structure contained high content of cis-1,4 structures,the content is about 90%,and the gel content of polymers is less(2-10%),but the relative molecular mass of polymer is also low.But when n-heptane is the solvent,the structures of polymers contained cis-1,4 and 3,4 structure,the content of 3,4 structure is in 15-35%,but the gel content of products is high,and molecular weight is higher than products using toluene as solvent.