Hyperbranched Polyethylene Ionomers Containing Cationic Tetralkylammonium Ions Synthesized by Pd–Diimine-Catalyzed Direct Ethylene Copolymerization with Ionic Liquid Comonomers

1T-2H Mixed-Phase MoS2 Stabilized with a Hyperbranched Polyethylene Ionomer for Mg2+ /Li+ Co-Intercalation Toward High-Capacity Dual-Salt Batteries

Dual-salt magnesium/lithium-ion batteries (MLIBs) benefit from fast lithium ion diffusion on the cathode side while providing safety due to the dendrite-free Mg2+ stripping/plating mechanism on the anode side. Bulk MoS2 (B-MoS2 ), as a cathode for magnesium-ion batteries (MIBs), suffers from low conductivity and relatively van der Waals gaps and, consequently, resists against divalent Mg2+ insertion due to the high Coulombic interactions. In MLIBs, it exhibits a Daniell-cell type mechanism with the sole accommodation of Li+ . In this paper, the synthesis of a 1T/2H mixed-phase MoS2 (MP-MoS2 ) modified with a hyperbranched polyethylene ionomer, I@MP-MoS2 , for high-capacity MLIBs with a distinct Mg2+ /Li+ co-intercalation mechanism is reported. Benefiting from the enhanced conductivity (due to 53% metallic 1T phase), expanded van der Waals gaps (79% expansion compared to B-MoS2 , 1.11 vs 0.62 nm), and enhanced interactions with THF-based electrolytes following the modification, I@MP-MoS2 shows a dramatically increased Mg2+ storage compared to its parent analogue (144 mAh g-1 vs ≈2 mAh g-1 at 20 mA g-1 ). In MLIBs, I@MP-MoS2 is demonstrated to exhibit remarkable specific capacities up to ≈270 mAh g-1 at 20 mA g-1 through a Mg2+ /Li+ co-intercalation mechanism with 87% of capacity retention over 200 cycles at 100 mA g-1 .

Ortho-Functionalized Dibenzhydryl Substituents in α-Diimine Pd Catalyzed Ethylene Polymerization and Copolymerization

Sterically bulky diarylmethyl-based ligands have received increasing attention in the field of late-transition-metal catalyzed olefin polymerization. Ortho-substituents may have a significant impact on the performance of diarylmethyl-based α-diimine Pd catalysts. In this contribution, a series of α-diimine Pd catalysts bearing ortho-methoxyl/hydroxyl functionalized dibenzhydryl units were prepared, characterized, and investigated in ethylene polymerization and copolymerization with methyl acrylate (MA). The catalytic performances were improved by introducing more ortho-substituents. The catalysts exhibited good thermal stabilities at high temperatures, producing branched polyethylenes. The catalysts bearing hydroxyl groups possessing intramolecular H-bonding, resulted in slightly higher incorporation ratios of MA unit when compared with the catalysts bearing methoxyl groups.

Ionic Liquid-Grafted Polyamide 6 by Radiation-Induced Grafting: New Strategy To Prepare Covalently Bonded Ion-Containing Polymers and their Application as Functional Fibers

Ion-containing polymers are of great importance for its unique structure and properties. An ion-containing polyamide 6 (PA6) was prepared by grafting an ionic liquid, 1-vinyl-3-butyl imidazole chloride [VBIM][Cl], onto the main chain of PA6 using radiation-induced grafting. The grafted ions on the PA6 main chain significantly influenced the structure and properties of the PA6 matrix. The ions form nanoscale aggregations without inducing further microphase separation. Acting as a physical "cross-linking point," each aggregation enhanced inter/intrachain interactions, which increased the viscosity, storage modulus, and relaxation time and reduced the ability of PA6 to crystallize. However, the bulky cations of the grafted ionic liquid can also be seen as "spacers," which enlarge the distance among chains and reduce the strength of the hydrogen bonds inherently existing in the PA6 matrix. The "cross-linking points" and "spacers" of ions as well as the hydrogen bonds of PA6 take effect collectively in the system. Moreover, the ion-containing PA6 retains good melt processability compared with PA6, despite increased viscosity, and can be easily melt-spun into fibers. Fibers prepared from ion-containing PA6 showed improved mechanical properties and antistatic performance and exhibited the expected antibacterial properties, especially with regard to Escherichia coli. Inspiringly, covalently bonding ions to the PA6 main chain offers a new strategy for fabricating functional fibers with permanent antistatic and antibacterial properties.

"Living" Polymerization of Ethylene and 1-Hexene Using Novel Binuclear Pd⁻Diimine Catalysts

We report the synthesis of two novel binuclear Pd–diimine catalysts and their unique behaviors in initiating “living” polymerization of ethylene and 1-hexene. These two binuclear catalysts, [(N^N)Pd(CH₂)₃C(O)O(CH₂)_mO(O)C(CH₂)₃Pd(N^N)](SbF₆)₂ (3a: m = 4, 3b: m = 6) (N^N≡ArN=C(Me)–(Me)C=NAr, Ar≡2,6–(iPr)₂C₆H₃), were synthesized by simply reacting [(N^N)Pd(CH₃)(N≡CMe)]SbF₆ (1) with diacrylates, 1,4-butanediol diacrylate and 1,6-hexanediol diacrylate, respectively. Their unique binuclear structure with two identical Pd–diimine acrylate chelates covalently linked together through an ester linkage was confirmed by NMR and single crystal XRD measurements. Ethylene “living” polymerizations were carried out at 5 °C and under ethylene pressure of 400 and 100 psi, respectively, with the binuclear catalysts, along with a mononuclear chelate catalyst, [(N^N)Pd(CH₂)₃C(O)OMe]SbF₆ (2), for comparison. All the polyethylenes produced with both binuclear catalysts show bimodal molecular weight distribution with the number-average molecular weight of the higher molecular weight portion being approximately twice that of the lower molecular weight portion. The results demonstrate the presence of monofunctional chain growing species resembling catalyst 2, in addition to the expected bifunctional species leading to bifunctional “living” polymerization, in the polymerization systems. Both types of chain growing species exhibit “living” characteristics under the studied conditions, leading to the simultaneous linear increase of molecular weight in both portions. However, when applied for the “living” polymerization of 1-hexene, the binuclear catalyst 3a leads to polymers with only monomodal molecular weight distribution, indicating the sole presence of monofunctional chain growing species. These two binuclear catalysts are the first Pd–diimine catalysts capable of initiating bifunctional ethylene “living” polymerization.

Efficient, robust surface functionalization and stabilization of gold nanorods with quaternary ammonium-containing ionomers as multidentate macromolecular ligands

Quaternary ammonium-containing ionomers are a novel class of multidentate macromolecular surface ligands for efficient functionalization and stabilization of gold nanorods.