The incorporation of comonomers during ethylene polymerization can efficiently modulate important material properties of the polyolefins. Utilizing bioresourced comonomers for the generation of high‐performance polyolefin materials is attractive from a sustainability point of view. In this contribution, bioresourced eugenol and related comonomers were incorporated into polyolefins through palladium‐catalyzed copolymerization and terpolymerization reactions. Importantly, high‐molecular‐weight catechol‐functionalized polyolefins can be generated. The introduction of different metal ions induces efficient interactions with the incorporated catechol groups, leading to enhanced mechanical properties and self‐healing properties. Moreover, the catechol functionality can greatly improve other properties such as surface properties, adhesion properties, and compatibilizing properties. The catechol‐functionalized polyolefin was demonstrated as a versatile platform polymer for accessing various materials with dramatically different properties. 相似文献
The facile and reversible interconversion between neutral and oxidized forms of palladium complexes containing ferrocene‐bridged phosphine sulfonate ligands was demonstrated. The activity of these palladium complexes could be controlled using redox reagents during ethylene homopolymerization, ethylene/methyl acrylate copolymerization, and norbornene oligomerization. Specifically in norbornene oligomerization, the neutral complexes were not active at all whereas the oxidized counterparts showed appreciable activity. In situ switching between the neutral and oxidized forms resulted in an interesting “off” and “on” behavior in norbornene oligomerization. This work provides a new strategy to control the olefin polymerization process. 相似文献
The introduction of even a small amount of polar functional groups into polyolefins could excise great control over important material properties. As the most direct and economic strategy, the transition‐metal‐catalyzed copolymerization of olefins with polar, functionalized monomers represents one of the biggest challenges in this field. The presence of polar monomers usually dramatically reduces the catalytic activity and copolymer molecular weight (to the level of thousands or even hundreds Da), rendering the copolymerization process and the copolymer materials far from ideal for industrial applications. In this contribution, we demonstrate that these obstacles can be addressed through rational catalyst design. Copolymers with highly linear microstructures, high melting temperatures, and very high molecular weights (close to or above 1 000 000 Da) were generated. The direct synthesis of polar functionalized high‐molecular‐weight polyethylene was thus achieved. 相似文献
Primary alcohol‐functionalized β‐diketones (bdks) are successfully synthesized via facile one‐step Claisen condensation between aromatic monoketones and ε‐caprolactone (ε‐CL). To demonstrate application potentials, these bdk alcohols are used to chelate with various Lewis acids, including Tb (III), Eu (III), and B (III). It is discovered that the resulting Tb (III) and Eu (III) diketonate complexes can serve as both catalysts and initiators for ring‐opening polymerization (ROP) under solvent‐free conditions, using lactide monomer as an example. The polylactides (PLAs) thus obtained exhibit luminescence properties characteristic of Tb (III) and Eu (III), respectively. On the other hand, boron‐chelated diketone can initiate ROP of lactide in the presence of Sn(oct)2, and affords a PLA material with dual‐emission, i.e., fluorescence and room temperature phosphorescence. The synthesis described here represents a shortcut for the preparation of bdk‐based macroligands and subsequent functional materials.
<正>Introduction of polar comonomers into polyethylene is highly challenging, paving the way to tuning the copolymers’ mechanical properties, adhesion/compatibility, and biodegradability. Polar-group tolerant single-site palladium and, more tempting, nickel-based catalysts have demonstrated promising reactivities in the ethylene copolymerization with polar comonomers via coordination/insertion mechanism, providing tighter control of polymer micro- 相似文献