α-二亚胺镍催化乙烯等温与非等温链转移聚合研究

研究了α-二亚胺镍催化剂在链转移剂(ZnEt_2)的作用下催化乙烯等温与非等温聚合行为,并利用凝胶渗透色谱法(GPC)和核磁共振法(~(13)CNMR)对所得聚烯烃进行表征。结果发现:无论在等温还是非等温条件下,α-二亚胺镍催化剂催化乙烯聚合所得的聚烯烃的分子量分布都变窄;等温聚合体系中,链转移反应导致分子量明显降低,而非等温体系具有活性聚合的特征,分子量有可能增加;在链转移与链行走竞争反应中,链转移反应明显抑制了链行走反应,控制聚烯烃的支化度。

Ethylene chain transfer polymerization using α-diimine nickel complex under isothermal and non-isothermal conditions

The ethylene polymerization behaviors of the α-diimine catalyst in the presence of chain transfer agent (ZnEt2) is investigated under isothermal and non-isothermal conditions, and gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy (13CNMR) are used to characterize the polyolefins. Results show that the chain transfer polymerization led to significantly narrow the molecular weight distribution both under isothermal and non-isothermal conditions, and chain transfer polymerization reduced obviously molecular weight under isothermal condition, while the characteristics of living polymerization under non-isothermal conditions possibly resulted in increasing molecular weight. In the competition with chain walking reaction, chain transfer reaction inhibited availably the reaction of chain walking to control the branching density of polyolefin.