Rapid and Selective Photo-degradation of Polymers: Design of an Alternating Copolymer with an o-Nitrobenzyl Ether Pendant

The development of polymers with on-demand degradability is required to alleviate the current global issues on polymer-waste pollution. Therefore, we designed a vinyl ether monomer with an o-nitrobenzyl (oNBn) group as a photo-deprotectable pendant (oNBnVE) and synthesized an alternating copolymer with an oNBn-capped acetal backbone via cationic copolymerization with p-tolualdehyde (pMeBzA). The resultant alternating copolymer could be rapidly degraded into lower-molecular-weight compounds upon simple exposure to UV irradiation without any reactants or catalysts, while it was sufficiently stable toward heat and ambient light. This degradation proceeds via cleavage of the hemiacetal structure generated upon photo-deprotection of the oNBn pendant. The oNBn-peculiar degradability allowed the exclusive photo-degradation of the oNBnVE/pMeBzA segments in a diblock copolymer composed of oNBnVE/pMeBzA and benzyl vinyl ether (BnVE)/pMeBzA segments.     

Decorating Channel Walls in Metal–Organic Frameworks with Crown Ethers for Efficient and Selective Separation of Radioactive Strontium(II)

Nuclear accidents and the improper disposal of nuclear wastes have led to serious environmental radioactive pollutions. The rational design of adsorbents for the highly efficient separation of strontium(II) is essential in treating nuclear waste and recovering radioactive strontium resources. Metal–organic frameworks (MOFs) are potential materials for the separation of aqueous metal ions owing to their designable structure and tunable functionality. Herein, a novel 3D MOF material MOF-18Cr6, in which 1D channels are formed using 18-crown-6-ether-containing ligands as channel walls, is fabricated for strontium(II) separation. In contrast to traditional MOFs designed by grafting functional groups in the framework pores, MOF-18Cr6 possesses regular 18-crown-6-ether cavities on the channel walls, which not only can transport and intake strontium(II) via the channels, but also prevent blockage of the channels after the binding of strontium(II). Consequently, the functional sites are fully utilized to achieve a high strontium(II) removal rate of 99.73 % in simulated nuclear wastewater. This study fabricates a highly promising adsorbent for the separation of aqueous radioactive strontium(II), and more importantly, can provide a new strategy for the rational design of high-performance MOF adsorbents for separating target substances from complex aqueous environments.     

Green Ether Electrolytes for Sustainable High-voltage Potassium Ion Batteries

Ether-based electrolytes are promising for secondary batteries due to their good compatibility with alkali metal anodes and high ionic conductivity. However, they suffer from poor oxidative stability and high toxicity, leading to severe electrolyte decomposition at high voltage and biosafety/environmental concerns when electrolyte leakage occurs. Here, we report a green ether solvent through a rational design of carbon-chain regulation to elicit steric hindrance, such a structure significantly reducing the solvent‘s biotoxicity and tuning the solvation structure of electrolytes. Notably, our solvent design is versatile, and an anion-dominated solvation structure is favored, facilitating a stable interphase formation on both the anode and cathode in potassium-ion batteries. Remarkably, the green ether-based electrolyte demonstrates excellent compatibility with K metal and graphite anode and a 4.2 V high-voltage cathode (200 cycles with average Coulombic efficiency of 99.64 %). This work points to a promising path toward the molecular design of green ether-based electrolytes for practical high-voltage potassium-ion batteries and other rechargeable batteries.     

High-Performance Lithium Metal Batteries Enabled by a Fluorinated Cyclic Ether with a Low Reduction Potential

Electrolyte engineering is crucial for developing high-performance lithium metal batteries (LMB). Here, we synthesized two cosolvents methyl bis(fluorosulfonyl)imide (MFSI) and 3,3,4,4-tetrafluorotetrahydrofuran (TFF) with significantly different reduction potentials and add them into LiFSI-DME electrolytes. The LiFSI/TFF-DME electrolyte gave an average Li Coulombic efficiency (CE) of 99.41 % over 200 cycles, while the average Li CEs for MFSI-based electrolyte is only 98.62 %. Additionally, the TFF-based electrolytes exhibited a more reversible performance than the state-of-the-art fluorinated 1,4-dimethoxylbutane electrolyte in both Li||Cu half-cell and anode-free Cu||LiNi_0.8Mn_0.1Co_0.1O₂ full cell. More importantly, the decomposition product from bis(fluorosulfonyl)imide anion could react with ether solvent, which destroyed the SEI, thus decreasing cell performance. These key discoveries provide new insights into the rational design of electrolyte solvents and cosolvents for LMB.     

Stabilizing Interfaces in High-Temperature NCM811-Li Batteries via Tuning Terminal Alkyl Chains of Ether Solvents

Ether electrolytes are promising for lithium metal batteries. Despite the intensive research in recent years, most state-of-the-art ether electrolytes still cannot form reliable electrode-electrolyte interfaces in NCM811-Li batteries at diluted concentrations, especially in those operating at elevated temperatures. We report a simple but effective strategy to break this bottleneck and stabilize interfaces in high-temperature NCM811-Li batteries in ether electrolytes. We propose that by gradually extending the terminal groups of glycol diethers from methyl groups to n-butyl groups, the comprehensive stability of ether electrolytes is improved. An anion-dominated solvation structure is realized at a concentration of 1 M. Accordingly, the electrode-electrolyte interactions are suppressed, and a thinner, denser, and more inorganic-rich solid- /cathode-electrolyte interface is achieved. Additionally, the surface phase transition and structural degradation of NCM811 cathode are alleviated. Consequently, in the ethylene glycol dibutyl ether-based electrolyte, the Coulombic efficiency for Li−Cu cells working at 60 °C is boosted to 99.41 % with a cycling life of over 200 cycles. The lifespan of high-temperature NCM811-Li cells is prolonged by more than 400 % with a stable average Coulombic efficiency of 99.77 % at quasi-practical conditions of 50 μm Li, lean electrolyte of 10 μL mAh⁻¹, and medium-high cathode loading of >2.2 mAh cm⁻².     

An Electron-Deficient CpE Iridium(III) Catalyst: Synthesis,Characterization, and Application to Ether-Directed C−H Amidation

The synthesis, characterization, and catalytic performance of an iridium(III) catalyst with an electron-deficient cyclopentadienyl ligand ([Cp^EIrI₂]₂) are reported. The [Cp^EIrI₂]₂ catalyst was synthesized by complexation of a precursor of the Cp^E ligand with [Ir(cod)OAc]₂, followed by oxidation, desilylation, and removal of the COD ligand. The electron-deficient [Cp^EIrI₂]₂ catalyst enabled C−H amidation reactions assisted by a weakly coordinating ether directing group. Experimental mechanistic studies and DFT calculations suggested that the high catalytic performance of [Cp^EIrI₂]₂ is due to its electron-deficient nature, which accelerates both C−H activation and Ir^V-nitrenoid formation.     

Direct ether formation of semibenzopinacol moieties in a photopolymerization system featured constant intensity of absorbed light

In a special photopolymerization reaction system, the reactivity of semibenzopinacol moieties was examined. Structural analysis by 1D/2D NMR showed that the hydroxyl groups of the semibenzopinacol moieties after hydrogen abstraction reaction have reacted directly to form a new ether structure instead of the cleavage of a C-C bond in a photopolymerization system featured constant intensity of absorbed light when there is only vinyl acetate added. In order to clarify this new reaction, comparative experiments and several characterization methods were applied. Results revealed that poly(vinyl acetate) radicals initiated by UV irradiation or benzophenone/triethanolamine system, and UV irradiation under or above 300 nm, were two necessary factors for the formation of the new ether structure from hydroxyl groups of semibenzopinacol moieties.     

(Liquid + liquid) equilibrium in binary systems of isomeric C8 aliphatic monoethers with acetonitrile and its interpretation by the COSMO-SAC model

The (liquid + liquid) solubility curves have been determined by a synthetic method for six binary mixtures of [acetonitrile + {heptyl methyl ether CH₃OⁿC₇H₁₅, or ethyl hexyl ether C₂H₅OⁿC₆H₁₃, or pentyl propyl ether ⁿC₃H₇OⁿC₅H₁₁, or isopentyl propyl ether ⁿC₃H₇Oⁱ C₅H₁₁, or dibutyl ether ⁿC₄H₉OⁿC₄H₉, or butyl isobutyl ether ⁿC₄H₉OⁱC₄H₉}]. The possibility of the COSMO-SAC model to account for the thermodynamic differences between these systems has been tested and the discussion on the influence of screening charge of ethers on the system properties was undertaken.     

Influence of Polar Modifiers on Microstructure of Polybutadiene Obtained by Anionic Polymerization. Part 2: Lewis Base (σ) Amine-Ether and Ether-Type Polar Modifiers

The influence of Lewis base (σ complex) amine-ether and ether-type polar modifiers on the microstructure of polybutadiene obtained by anionic polymerization was studied. Analysis of FT-IR-ATR, ¹H, and ¹³C NMR spectral data for polybutadienes obtained in the presence of the complexing agents showed that increase of concentration of all tested polar modifiers very strongly promoted formation of 1,2 butadiene isomeric structures, especially increasing the content of vinyl–vinyl and vinyl–trans-1,4 diads.     

近红外光谱法快速检测烟草中的石油醚提取物

为适应快速分析烟草中石油醚提取物含量的需要,建立了近红外光谱法预测烟草中石油醚提取物含量的方法,考察了光谱预处理方法、谱区范围对石油醚提取物含量预测值的影响。该方法具有简便、快速、低消耗、低成本、不破坏样品及重现性好等优点,且其预测值与烟草行业标准方法测定值较为接近,适用于大批量烟叶样品石油醚提取物含量的快速分析。