State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022, China.
School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China.
Molecules. 2022 Dec 15;27(24):8942. doi: 10.3390/molecules27248942.
Among various catalyst design strategies used in the α-diimine nickel(II) and palladium(II) catalyst systems, the unsymmetrical strategy is an effective and widely utilized method. In this contribution, unsymmetrical nickel and palladium α-diimine catalysts ( and ) derived from the dibenzobarrelene backbone were constructed via the combination of pentiptycenyl and diisopropylphenyl substituents, and investigated toward ethylene (co)polymerization. Both of these catalysts were capable of polymerizing ethylene in a broad temperature range of 0-120 °C, in which could maintain activity in the level of 10 g mol h even at 120 °C. The branching densities of polyethylenes generated by both nickel and palladium catalysts could be modulated by the reaction temperature. Compared with symmetrical and , exhibited the highest activity, the highest polymer molecular weight, and the lowest branching density. In addition, could produce copolymers of ethylene and methyl acrylate, with the polar monomer incorporating both on the main chain and the terminal of branches. Remarkably, the ratio of the in-chain and end-chain polar monomer incorporations could be modulated by varying the temperature.
在用于 α-二亚胺镍(II)和钯(II)催化剂体系的各种催化剂设计策略中，不对称策略是一种有效且广泛应用的方法。在本研究中，通过将戊基并菲基和二异丙基苯基取代基组合，构建了源自二苯并桶烯骨架的不对称镍和钯α-二亚胺催化剂（和），并将其用于乙烯（共聚）聚合。这两种催化剂都能够在 0-120°C 的较宽温度范围内聚合乙烯，其中在 120°C 时仍能保持 10 g mol h 的活性水平。通过反应温度可以调节由镍和钯催化剂生成的聚乙烯的支化密度。与对称的和相比，表现出最高的活性、最高的聚合物分子量和最低的支化密度。此外，还可以生成乙烯和甲基丙烯酸甲酯的共聚物，其中极性单体同时存在于主链和支链的末端。值得注意的是，通过改变温度可以调节链内和端基极性单体的掺入比。
