Functionalization and block reactions of polyolefins using metallocene catalysts and borane reagents

This paper discusses the utilization of metallocene catalyst and borane reagent for the preparation of functionalized polyolefins and diblock copolymers containing polyolefin and functional polymer segments. Two advantages in the metallocene catalyst with strained ligand geometry are (i) the excellent incorporation of high α-olefin, including borane-containing α-olefin, into polyolefin chain with relatively narrow molecular weight and composition distributions, (ii) the production of polyolefin with chain end unsaturation which can be effectively hydroborated to form the borane- terminated polyolefin. In turn, the borane groups in polyolefin are very versatile intermediates, which not only can be quantitatively interconverted to various functional groups but also can easily be oxidized to produce 'living' polymeric radicals for radical polymerization. With the coexistence of free radical-polymerizable monomers, we have prepared many diblock copolymers, such as PP-b-PMMA, PP-b PVA and PP-b-PS, most of them would be very difficult to prepare by other methods.