FUNCTIONALIZATION OF POLYETHYLENE USING BORANE REAGENTS AND METALLOCENE CATALYSTS

A new method to prepare functionalized polyethylene involving borane intermediates and transition metal catalysts is described. Two processes, direct and post polymerizations, were employed to prepare borane-containing polyethylene (PE-B), which can be transformed to functionalized polyethylene (LLDPE-f) with various functional groups, such as -BR(2), -OH, -NH2, -OSi(CH3)(3). In the direct process, the PE-B copolymers were prepared in one step by copolymerization of ethylene with a borane monomer (omega-borane-alpha-olefin). The post polymerization process requires two steps: copolymerization of ethylene and 1,4-hexadiene, and subsequential hydroboration reaction of unsaturated PE. Three transition metal catalysts, including two homogeneous metallocene (Cp(2)ZrCl(2) [bis(cyclopentadienyl) zirconium dichloride] and Et(Ind)(2)ZrCl2 [1,1'-ethylenedi-eta(5)-indenyl-zirconium dichloride] with MAO (methylaluminoxane)) and one heterogeneous (TiCl3 . AA/Et(2)AlCl) ones, were studied in the copolymerization reactions. The single site Et(Ind)(2)ZrCl2/MAO homogeneous catalyst, with a strained ligand geometry and opened active site, is by far the most effective system in the incorporation of high olefins into polyethylene structures.