Copolymerization of norbornene and butyl methacrylate at elevated temperatures by a single centre nickel catalyst bearing bulky bis(α-diimine) ligand with strong electron-withdrawing groups

Abstract

A bulky α-diimine ligand with a three dimensional geometry and strong electron-withdrawing groups (–NO₂), 9,10-dihydro-9,10-ethanoanthracene-11,12-di(p-PhNO₂)imine(L), and a corresponding single nickel catalyst (NiL₂Br₂) were synthesized, and the molecular structure of the NiL₂Br₂ catalyst was confirmed by X-ray crystallography. After being activated with B(C₆F₅)₃, the NiL₂Br₂ catalyst exhibited high activity towards homopolymerization and copolymerization of norbornene(NB) and butyl methacrylate (BMA). The obtained poly(NB-co-BMA)s were confirmed to be vinyl-addition copolymers and noncrystalline. The BMA monomer content in the copolymers could be controlled up to 6.0%–78.7% by varying the BMA monomer feed ratios from 10% to 90%. The obtained poly(NB-co-BMA)s exhibited high thermal stability (T_d > 390 °C), high-molecular-weight and narrow molecular weight distribution (PDI ≤ 1.4) and could be processed into films with good transparency and mechanical properties.