Accessing Multiple Catalytically Active States in Redox-Controlled Olefin Polymerization

The majority of work in the field of olefin polymerization catalysis has been focused on ligand modifications. In this work, we describe an alternative strategy for the modulation of olefin polymerization and copolymerization processes. The two ferrocenyl units in an α-diimine palladium catalyst can be oxidized in a stepwise fashion. This stepwise redox control can be used to modulate the catalyst properties during the homopolymerization of ethylene and 1-hexene, as well as the copolymerizations of ethylene with norbornene, methyl acrylate, and 5-norbornene-2-yl acetate. Moreover, polymer microstructure and polydispersity can be controlled during these stepwise oxidation processes.

烯烃聚合催化领域的绝大多数研究工作均聚焦于配体修饰。本研究提出了一种用于调控烯烃聚合与共聚过程的替代策略。α-二亚胺钯催化剂（α-diimine palladium catalyst）中的两个二茂铁单元可实现分步氧化。该分步氧化还原调控手段可用于调控乙烯、1-己烯的均聚，以及乙烯与降冰片烯、丙烯酸甲酯、乙酸5-降冰片烯-2-基酯的共聚过程中的催化剂性能。此外，在上述分步氧化过程中，聚合物的微观结构与多分散性也可得到调控。