Switchable Synthesis of Ethylene/Acrylate Copolymers by a Dinickel Catalyst: Evidence for Chain Growth on Both Nickel Centers and Concepts of Cation Exchange Polymerization
Shuoyan Xiong, Heather A. Spinney, B.C. Bailey, Briana S. Henderson, Adjeoda A. Tekpor, Matthew R. Espinosa, Paramita Saha, Theodor Agapie
Abstract
High Resolution Image Download MS PowerPoint Slide A dinickel complex, X-Ni 2, was developed and demonstrated to have a high performance in ethylene/acrylate copolymerization. Further mechanistic studies revealed that X-Ni 2 performs acrylate insertion at both Ni centers at distinct rates. Addition of NaBAr F 24 to X-Ni 2 leads to 1:1 binding and serves as a switch for tuning catalytic activity, copolymer MW and acrylate incorporation. NMR studies of cation binding, when present in substoichiometric amounts, suggest a dynamic process involving cation exchange. This phenomenon provides an alternative strategy for controlling chain growth in polar polyolefin synthesis and was probed herein.