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.

Hydrogen‐Bonding‐Induced Heterogenization of Nickel and Palladium Catalysts for Copolymerization of Ethylene with Polar Monomers

“…This approach is simple and widely practiced, but usually suffers from low activity and low comonomer incorporation because of the steric hindrance around the active species caused by the bulky solid counter anion [22–27] . The second approach is the chemical tethering of a metal complex to a solid support ( B , Scheme 1), which often suffers from complicated syntheses and difficult in catalyst characterization/modification [28–30] . Thirdly, metal complexes can be heterogenized in situ through the reactions of specially designed reactive sites (such as hydroxy or amino groups) on the ligand with a supported aluminum co‐catalyst ( C , Scheme 1), which differs from approach A by covalently linking the metal complex to the supported cocatalyst [31–35] .…”

Influence of Silica-Supported Alkylaluminum on Heterogeneous Zwitterionic Anilinonaphthoquinone Nickel and Palladium-Catalyzed Ethylene Polymerization and Copolymerization with Polar Monomers

“…Among them, a widely practiced method is the simple formation of ion pairs between a metal active center and solid-supported cocatalysts. However, this often leads to poor polymerization properties because the sterically large solid counter anion around the active species may hinder the monomer coordination process. − On the other hand, although the approach using the solid-supported metal complex through remotely bounded direct chemical tethering of the ligand and the solid surface can maintain good polymerization properties, it involves complicated catalyst preparation and characterization processes. − Therefore, in situ heterogenization of late transition metal complexes was accomplished through the covalent attachment of the solid-supported cocatalyst and specially designed functional sites on the ligand, which not only retain good polymerization properties but also display features of relatively easy preparation processes and characterization . Despite these achievements, effective catalytic systems based on nickel or palladium catalysts available for the direct copolymerization of olefins with polar monomers have remained largely unexplored .…”

Hydrogen‐Bonding‐Induced Heterogenization of Nickel and Palladium Catalysts for Copolymerization of Ethylene with Polar Monomers

“…[22][23][24][25][26][27] The second approach is the chemical tethering of a metal complex to a solid support (B, Scheme 1), which often suffers from complicated syntheses and difficult in catalyst characterization/modification. [28][29][30] Thirdly, metal complexes can be heterogenized in situ through the reactions of specially designed reactive sites (such as hydroxy or amino groups) on the ligand with a supported aluminum co-catalyst (C, Scheme 1), which differs from approach A by covalently linking the metal complex to the supported cocatalyst. [31][32][33][34][35] Still, this approach requires complicated ligand syntheses and the utilization of expensive and pyrophoric aluminum cocatalysts.…”