Xu Mengli, Yu Fan, Li Pei, Xu Guoyong, Zhang Shaojie, Wang Fuzhou
Institutes of Physical Science and Information Technology, School of Computer Science and Technology, Anhui University, Hefei 230601, Anhui, China.
Inorg Chem. 2020 Apr 6;59(7):4475-4482. doi: 10.1021/acs.inorgchem.9b03647. Epub 2020 Mar 19.
Improving the efficiency of chain initiation is highly important and also highly challenging in the development of olefin polymerization catalysts. A series of 2-methylallyl-based nickel complexes supported by aryl--bridged diphosphazane monoxide (PNPO) ligands containing different electronic and steric substituents were prepared and characterized. These nickel complexes are highly active single-component catalysts for ethylene polymerization and copolymerization with methyl acrylate (MA). 2-Methylallyl substituent on the allyl catalysts led to an increase in the efficiency of chain initiation compared with the corresponding allyl-based analogues, improving the catalytic performances with high activity (up to 4.02 × 10 g PE (mol Ni) h). Linear polyethylenes with high molecular weight, narrow PDI values, and high melting temperatures were generated. Most importantly, these 2-methylallyl nickel catalysts can promote ethylene-MA copolymerization to afford functionalized polyethylenes with MA incorporation of up to 7.0 mol %. The current work demonstrates that the change of initiating units can lead to enhancement in catalyst performances. This provides an alternative, simple, and potentially general strategy to improve the properties of different catalyst systems.
在烯烃聚合催化剂的开发中，提高链引发效率非常重要且极具挑战性。制备并表征了一系列由含有不同电子和空间取代基的芳基桥联二磷氮烷单氧化物（PNPO）配体支撑的基于2-甲基烯丙基的镍配合物。这些镍配合物是用于乙烯聚合以及与丙烯酸甲酯（MA）共聚的高活性单组分催化剂。与相应的基于烯丙基的类似物相比，烯丙基催化剂上的2-甲基烯丙基取代基导致链引发效率提高，以高活性（高达4.02×10⁶ g PE/(mol Ni) h）改善了催化性能。生成了具有高分子量、窄PDI值和高熔点的线性聚乙烯。最重要的是，这些2-甲基烯丙基镍催化剂可以促进乙烯与MA的共聚，得到MA掺入量高达7.0 mol%的功能化聚乙烯。目前的工作表明，引发单元的改变可以导致催化剂性能的提高。这为改善不同催化剂体系的性能提供了一种替代的、简单且可能通用的策略。
