The Studies Of Microstructure And Synthesis Of Functional Hyperbranched Polyethylene

Hyperbranched polymer is a macromolecule of the very high branching degree. They hold the character of low-viscosity, good-rheologic and lots of functional group, which is belong to the traditional linear polymer. In the later years, there are some hyperbranched polyolefin. The polyolefin is a current macromolecular material, which production and kinds are more and more. They are more high-powered and functional to develop. One of development is to synthesize a new catalyst which is used to modify the polymer. At 1995, the Ni/Pa α-diimine catalyst was reported to copolymerize ethylene with α-olefin by Brookhart. It can synthesize the hyperbranched polyethylene from feed-only ethylene by the mechanics of "chain-walking".In this paper, the copolymerization of ethylene with polar comonomer to hyperbranched functional copolymer was studied by the late transition metal catalyst. The microstructure of copolymer was investigated. And the functional route was explored. In this study, the catalyst is 2,3-bis-(2,6-di-methylphenyl-imino)hexane -nickel(II) -dibromide(MHNB). The polyethylene was synthesized by MHNB, which activity can arrive to 2 ×10⁶g/mol.Ni?hr. The influence of polymerization by the reactive conditions was investigated. Besides, the comonomers of different protecting groups were synthesized. The copolymer of different molecular weight, branching and incorporation rate was copolymerized by ethylene and polar comonomers. The copolymerization activity influenced by temperature, polar comonomers of different protecting groups and the concentration of comonomer was studied. There was a large difference in activity of copolymerizing ethylene with polar comonomer which own different protecting groups. The bulky protecting group can result in a higher activity. The concentration of comonomer didn't influence the activity of copolymerization. There was an activity of 1.0 × 10⁶g/mol.Ni·hr. The activity of the copolymerization increased with temperature with its highest value at 20℃. Further increasingtemperature decreased the catalyst activity. The microstructure of copolymer was investigated in detail. The incorporation rate of comonomer was analyzed by ¹H NMR. The incorporation rate of comonomer was increasing by temperature at a constant concentration of comonomer. Because the activity of polymerization decreased with temperature, the conversion of comonomer decreased. Besides, the incorporation rate of comonomer increased as the concentration of comonomer. There was an incorporation rate of 0.3%-4.0%. The microstructure of copolymer was analyzed by ¹³C NMR. The degree of branches was obtained. The degree of branches of copolymer can reach above 100 at 1000 backbone carbon. The molecular weight of copolymer can be obtained by GPC, Mw of which were 4×10⁴-2.2×10⁵. The functionality of hyperbranched copolymer was investigated. The hydroxyl of copolymers was substituted by acryloyl chloride. The substitution product can be used in light-solidifying coating.