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
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 (Td > 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.