FUNCTIONALIZATION AND BLOCK REACTIONS OF POLYOLEFINS USING METALLOCENE CATALYSTS AND BORANE REAGENTS

This paper discusses the utilization of metallocene catalyst and boran e reagent for the preparation of functionalized polyolefins and dibloc k copolymers containing polyolefin and functional polymer segments. Tw o advantages in the metallocene catalyst with strained ligand geometry are (i) the excellent incorporation of high alpha-olefin, including b orane-containing alpha-olefin, into polyolefin chain with relatively n arrow molecular weight and composition distributions, (ii) the product ion of polyolefin with chain end unsaturation which can be effectively hydroborated to form the borane-terminated polyolefin. In turn, the b orane groups in polyolefin are very versatile intermediates, which not only can be quantitatively interconverted to various functional group s but also can easily be oxidized to produce 'living' polymeric radica ls for radical polymerization. With the coexistence of free radical-po lymerizable monomers, we have prepared many diblock copolymers, such a s PP-b-PMMA, PP-b-PVA and PP-b-PS, most of them would be very difficul t to prepare by other methods.