Outer‐Shell Self‐Supported Nickel Catalysts for the Synthesis of Polyolefin Composites

Abstract

In situ heterogeneous olefin polymerization has attracted much attention for the synthesis of polyolefin composites. However, the complicated syntheses of specially designed catalysts or the detrimental effects of interactions between catalyst and solid supports pose great challenges. In this contribution, an outer‐shell self‐supporting strategy was designed to heterogenize nickel catalysts on different fillers via precipitation homopolymerization of ionic cluster type polar monomer. These catalysts demonstrated high activity, good product morphology control, and stable performances in ethylene polymerization and copolymerization. Moreover, various polyolefin composites with great mechanical and customized properties can be efficiently synthesized.

Dual-Site Polymeric Heterogeneous α-Diimine Ni Catalysts with Tailored Spatial Distribution for Ethylene Polymerization

“…Polar polyolefin particles were precipitated from the solvent n -heptane due to the highly polar ionic cluster cross-linking networks. The nickel catalysts were coprecipitated. , Three classical Brookhart Ni catalysts without anchoring groups were used (Figure B). , The spatial distribution of the two catalytic components is controlled by the process of precipitation polymerization. The single-site A and B type-supported catalysts were easily prepared in one step.…”

“…The use of supported catalysts led to good product morphological control and avoidance of reactor fouling (Figure A). − Moreover, due to the polar polyolefin component derived from 10-undecenoic acid (containing ca. 2 wt % of polar monomer unit), the in-reactor blend resulting from the heterogeneous catalyst exhibits better hydrophilicity than the product of homogeneous polymerization (Figure B,C).…”

Emulsion Polymerization Strategy for Heterogenization of Olefin Polymerization Catalysts

“…Since the discovery of ethylene free radical polymerization in the 1930s and the development of olefin coordination polymerization in the 1950s, polyolefins have become one of the most important synthetic polymers in the world. , Over the past decades, the design and development of high-performance catalysts suitable for industrial polymerization processes have received significant attention from academia and industry. − Despite the large annual production of polyolefin materials, one of their greatest drawbacks is their nonpolar nature, which results in poor compatibility with polar materials, limiting their application in many fields. The introduction of polar functional groups can improve many properties, such as adhesion, compatibility, and dyeability, enabling the preparation of novel polyolefin-based functional materials. − Transition-metal-catalyzed coordination copolymerization of olefins with polar monomers holds great potential in obtaining polar-functionalized polyolefins, − which is regarded as one of the last holy grails in this field . Late-transition-metal olefin polymerization catalysts have been of interest due to their low oxophilicity and correspondingly high tolerance toward polar groups. − Furthermore, some late-transition-metal catalysts based on imino ligands can generate unique branched polyolefins by a chain walking mechanism, and the branch density and topology of these branched polyolefins can be adjusted by changing ligand structures or polymerization conditions. ,− …”

“…In the past 30 years, hundreds of homogeneous late-transition-metal-based olefin polymerization catalysts have been reported. − However, very few heterogeneous catalysts have been studied for the copolymerization of ethylene with polar comonomers. − Industrial polyolefin processes mainly use heterogeneous systems because of their great advantages in product morphological control, avoidance of reactor fouling, and stable production operations. − This represents one of the key challenges for the successful commercialization of late-transition-metal catalysts. Heterogenization of homogeneous metal catalysts on solid supports has been widely studied for catalytic organic reactions − and represents a promising strategy to address the above issue. − This is usually achieved via two methods: (a) combination of a solid support or a cocatalyst-modified support with a metal complex through a covalent bond, hydrogen bond, or coordination bond (Scheme A, left); (b) generation of ion pairs by mixing the solid support/cocatalyst with a transition-metal precatalyst (Scheme A, right). ,,− ,− Recently, Chen and co-workers reported an ionic cluster strategy that can enable product morphology control utilizing metal salt polar α-polar monomers (Scheme B) .…”

“…The introduction of polar functional groups can improve many properties, such as adhesion, compatibility, and dyeability, enabling the preparation of novel polyolefin-based functional materials. − Transition-metal-catalyzed coordination copolymerization of olefins with polar monomers holds great potential in obtaining polar-functionalized polyolefins, − which is regarded as one of the last holy grails in this field . Late-transition-metal olefin polymerization catalysts have been of interest due to their low oxophilicity and correspondingly high tolerance toward polar groups. − Furthermore, some late-transition-metal catalysts based on imino ligands can generate unique branched polyolefins by a chain walking mechanism, and the branch density and topology of these branched polyolefins can be adjusted by changing ligand structures or polymerization conditions. ,− …”