Silica-supported Ni(II) complex bearing [O^N] ligand and copolymerization to afford silica hybrid polynorbornenes nanocomposites

Abstract

In situ polymerization is an ideal technique to make a perfect dispersion of nanosilica into polymer matrixes. So, in this article, a novel silica-supported β-ketoamine nickel(II) dibromide precatalyst was efficiently prepared and used in in situ slurry polymerizations of norbornene (NB) to afford a highly productive NB addition polymerization system in combination with tris(pentafluorophenyl)borane (B(C₆F₅)₃) cocatalyst. It exhibited productivity of 176.8 kg of polynorbornene (mol Ni)⁻¹ h⁻¹ at a mole ratio of B/Ni = 20, and the catalyst deactivation kinetics in the early stage of polymerization fitted well by the first-order deactivation kinetics up to about 60 min. The catalyst system was also effective for the copolymerization of NB and 5-norbornene-2-carboxylic acid methyl ester to produce the addition-type copolymers with high-molecular-weights (3.28–3.45 × 10⁵ g mol⁻¹) and incorporation rates (8.1–49.1%) as well as narrow molecular weight distributions (polydispersity index = 1.6). The nanoparticles were confirmed to be well-dispersed in the polymer matrix with each individual nanoparticle surrounded by polymer. Transparency of nanocomposites could be kept up to about 60%. The brittleness of polymer was obviously improved, and the tensile strength of polymer film could be as high as 47.8 MPa.