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

Abstract

The practical synthesis of polar-functionalized polyolefins using transition-metal-catalyzed copolymerization of olefins with polar monomers is a challenge; the use of heterogeneous catalysts is little explored. Herein, we report the synthesis of heterogeneous naphthoquinone-based nickel (Ni/ SiO 2 ) and palladium (Pd/SiO 2 ) catalysts through hydrogen bonding interactions of the ligands with the silica surface. Ni/ SiO 2 exhibits high activities (up to 2.65 10 6 g mol À1 h À1 ) during the copolymerization of ethylene with 5-hexene-1-ylacetate, affording high-molecular-weight (M n up to 630 000) polar-functionalized semicrystalline polyethylene (comonomer incorporation up to 2.8 mol %), along with great morphology control. The resulting copolymers possess improved surface properties and great mechanical properties. Pd/SiO 2 can mediate ethylene copolymerization with polar monomers with moderate activity to produce high-molecular-weight copolymers with tunable comonomer incorporation.Scheme 1. Plausible heterogenization approaches for olefin polymerization catalysts.

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

“…Stable catalyst performance is desirable in practice because it increases the predictability of polymerization results. In contrast, in conventional heterogenization route (Figure 1C), the interaction between the support and the catalyst may significantly influence the steric and electronic effect of the catalysts as well as their catalytic performances, leading to dramatically reduced activity and molecular weight [7, 14, 35, 40–45] . These effects are often erratic and unpredictable and therefore undesirable in practice.…”

“…However, the typical heterogenization route remains largely unexplored in late transition metal olefin polymerization catalyst systems [7, 34–41] . In order to achieve high polymerization activity and universal applicability to different fillers, it is often necessary to synthesize new catalysts bearing specific anchoring groups (Figure 1C, right) [7, 34–43] . Furthermore, catalyst performances may be significantly altered due to the interaction of the support with the catalyst at the molecular level, resulting in poor predictability [1, 14, 35, 40–45] .…”

“…In order to achieve high polymerization activity and universal applicability to different fillers, it is often necessary to synthesize new catalysts bearing specific anchoring groups (Figure 1C, right) [7, 34–43] . Furthermore, catalyst performances may be significantly altered due to the interaction of the support with the catalyst at the molecular level, resulting in poor predictability [1, 14, 35, 40–45] . It may also result in significant decreases in (co)polymerization activity, molecular weight, and comonomer incorporation ratio [1, 13, 14, 40, 41] .…”

Tailor-Made Functional Polyolefins of Complex Architectures: Recent Advances, Applications, and Prospects

“…Typically, this class of catalysts produces highly branched amorphous polyolefins, e.g., hyperbranched polyethylene (HPBE), through the chain walking polymerization (CWP) mechanism. Although such functional copolymers are valuable because of their chain-end-functionalized microstructure, their polar monomer content is limited. , Numerous studies have been performed to develop new late-transition-metal-based catalysis with enhanced polar monomer incorporation. − Some comprehensive reviews and perspectives have recently been published on the progression in late-transition-metal-mediated polymerization of olefins with polar monomers. − This field has evolved dramatically in the past few years, and many high-performance catalysts have been developed. − However, this approach is still unable to manufacture more complex architectures such as block copolymers.…”

Bidentate Pyridyl‐Amido Hafnium Catalysts for Copolymerization of Ethylene with 1‐Octene and Norbornene

“…For example, through copolymerization of ethylene and propylene as well as their terpolymerization with diene comonomers, ethylene propylene rubbers (EPR/EPDM) have become one of the most widely used non‐tire elastomers with huge annual production [16–19] . The incorporation of some polar functionalized comonomers can efficiently alter the nonpolar nature of polyolefins and introduce new material properties [20–25] . The incorporation of a large content of α‐olefins can decrease crystallinity and enable elastic properties, leading to the generation of polyolefin elastomers (POEs) [26,27] .…”