| A series of nickel complexes based on?-ketiminato ligands bearing various an electron-donating or electron-withdrawing substituents on the para-position of the aniline group were synthesized and unambiguously characterized.All complexes exhibited high activity up to 1.56×106 gPE·molNi-1·h-1 toward ethylene polymerization,affording polymers with molecule weight up to 16600.The obtained polyethylenes were proved to have a few of methyl branches and exhibited low melting points.All complexes exhibited high activities up to 1.25-1.35×107 g PNB·mol Ni-1·h-1toward norbornene(NBE)addition polymerization(conversion>91.2%in 2 min)under low loading of B(C6F5)3(B/Ni=3)at 30?,affording polymers with high molecular weight around 3×106.Different levels of decrease in catalytic activities could be observed all catalysts as the reaction temperature increased,while complex bearing a strong electron-withdrawing-CF3 group showed the highest activity at 70?,while others exhibited notable decrease in catalytic activity with the raise in reaction temperature.All complexes also showed remarkable tolerance to polar groups and could efficiently promote the copolymerization of NBE with its polar derivatives,including NBE bearing small acetate and hydroxyl group,as well as bulky oligomers.The copolymerization apparent-conversion rate up to 97.0%.The incorporation of NBA and NBM up to 9.00mol%and 9.31mol%,respectively.Two macromolecular norbornene derivatives 5-Norbornene-2-yl methyl-polyol(NB-PPO)and 5-Norbornene-2-yl methyl dodecanoate(NMD),respectively,were synthesized and copolymerized with NBE.Copolymers with tunable comonomer incorporations(incorporation of monomers,I(NMD)=35.5mol%,I(NB-PPO)=4.58mol%)were obtained in high yields.All these newly obtained functional copolymers showed much improved solubility at room temperature. |
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