Copolymerization of Norbornene and Styrene Catalyzed by a Series of Bis(β-ketoamine) Nickel(II) Complexes in the Presence of Methylaluminoxane

Abstract

Random copolymerization of norbornene with styrene was studied by using a series of late metal catalysts/MAO. The precatalysts used here are nickel complexes with b-ketoamine ligands based on pyrazolone derivatives. The copolymers obtained here suggest that only one type of active species is present. Copolymers were characterized by 13C NMR, Gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and FT-IR spectra. The analyses of the product by 1H NMR and 13C NMR spectra gave the verification of “true” random vinyl addition copolymer. Varying the monomer feed ratio controlled the composition of the copolymers. A copolymerization reactivity ratio (rNBE = 20.35 and rSty = 0.027) indicates a much higher reactivity of norbornene, which suggests a coordination polymerization mechanism. The solubility and processability of the copolymers are improved relative to polynorbornene and the thermostability of the copolymers is improved relative to polystyrene.