Xu G, Ruckenstein E
Department of Chemical Engineering, State University of New York at Buffalo, Buffalo, New York 14260.
Macromolecules. 1998 Jul 28;31(15):4724-9. doi: 10.1021/ma980498d.
A new effective constrained geometry catalyst precursor for the ethylene/1-octene copolymerization, namely 2-methylbenz[e]indenylamido complex [eta5:eta1-(2-MeBenzInd)SiMe2NtBu]TiCl2 (4), was synthesized. Activated with methylaluminoxane (MAO), the complex 4 showed (a) an improved copolymerization activity and stability, (b) an enhanced comonomer incorporation in the copolymer, and (c) most importantly, an increased copolymer molecular weight, when compared with the previously employed catalysts. The polymerization conditions were found to have a significant effect on the catalyst activity, 1-octene incorporation, molecular weight, and even copolymer microstructure. For the copolymerization parameters, the values rE approximately 2.20 for ethylene and rO approximately 0.55 for 1-octene with rE.rO approximately 1.21 were obtained, reflecting a pronounced tendency for the random distribution of the comonomers in the copolymer chain. The 13C NMR analysis revealed that the E-O copolymer generated by the MAO-activated complex 4 has a regioirregular arrangement of the 1-octene repeat units as a result of some tail-to-tail incorporation of the 1-octene comonomer.
合成了一种用于乙烯/1-辛烯共聚的新型高效受限几何催化剂前体，即2-甲基苯并[e]茚基氨基络合物[η5:η1-(2-MeBenzInd)SiMe2NtBu]TiCl2（4）。与先前使用的催化剂相比，用甲基铝氧烷（MAO）活化后的络合物4表现出：（a）共聚活性和稳定性提高；（b）共聚单体在共聚物中的掺入量增加；（c）最重要的是，共聚物分子量增加。发现聚合条件对催化剂活性、1-辛烯掺入量、分子量甚至共聚物微观结构都有显著影响。对于共聚参数，得到乙烯的rE约为2.20，1-辛烯的rO约为0.55，rE·rO约为1.21，这反映出共聚单体在共聚物链中具有明显的无规分布趋势。13C NMR分析表明，由MAO活化的络合物4生成的E-O共聚物由于1-辛烯共聚单体的一些尾对尾掺入而具有1-辛烯重复单元的区域不规则排列。
