作者：Yi Liu, Hong-Xia Xiang, Kai-Ti Wang*, Gang Wu, You-Bing Li
关键字：copolymerization, cyclic olefin copolymers, olefin polymerization, polymeric intermediates, vanadium catalysts
论文来源：期刊
具体来源：Macromol. Chem. Phys
发表时间：2019年

Five β-ketoimine vanadium(III) catalysts with promising thermal stability are employed to promote efficient ethylene/dicyclopentadiene (DCPD), ethylene/5-ethylidene-2-norbornene (ENB), and ethylene/5-vinyl-2-norbornene (VNB) copolymerizations, respectively. These vanadium catalysts show high activities toward ethylene/DCPD and ethylene/ENB copolymerization, producing copolymers with high molecular weight and co-monomer incorporations. By contrast, they exhibit moderate activities toward ethylene/VNB copolymerization and afford copolymers with much lower molecular weight and co-monomer incorporation. This can be ascribed to less steric hindrance around the pendant vinyl group in VNB. All of the selected catalysts exhibit a single-site catalytic behavior during the copolymerization. These dienes enchained by vinyl-type addition via the intra cyclic C=C bonds of norbornene and the extra C=C bonds are totally maintained as unreacted. Besides, the conversion rates of the monomer, as well as the molecular weight and co-monomer contents of the copolymers can be effectively regulated by varying the structure of catalysts and the processing parameters.