Diethylene Glycol Research Articles

Performance Evaluation of PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA Equations of State for Predicting Density, Thermal Expansion Coefficient, Isothermal Compressibility, Isobaric Heat Capacity, Speed of Sound, and Saturated Vapor Pressure of Three Pure Ethylene Glycols and Their Mixtures

Ethylene glycols are a group of versatile industrial solvents with broad applications across various sectors. Accurate thermodynamic modeling of these compounds is essential for enhancing their utilization and optimizing industrial processes. Among the advanced models available, the Statistical Associating Fluid Theory (SAFT) type equation of state (EoS) stands out for its effectiveness in capturing the thermodynamic behavior of complex fluids. This study employs the PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA EoSs to model pure monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG), and their mixtures. Furthermore, the predictive capabilities of these models are critically evaluated for polyethylene glycol 400 (PEG 400). The performance of the PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA EoSs was evaluated for predicting key thermodynamic properties, including density, thermal expansion coefficient, isothermal compressibility, isobaric heat capacity, speed of sound, and saturated vapor pressure, for pure MEG, DEG, TEG, and PEG 400. Among the models, the PρT-SAFT demonstrated superior accuracy in modeling their properties. Subsequently, the volumetric properties and vapor–liquid equilibrium data of binary mixtures of MEG, DEG, and TEG were predicted using the same EoSs, without incorporating any binary interaction parameters. Under these conditions, the PρT-SAFT achieved the highest accuracy. Furthermore, predictions of the volumetric properties for the ternary mixture of MEG, DEG, and TEG also indicated that the PρT-SAFT outperformed the other models. The overall average absolute deviation percentages for the PρT-SAFT, PρT-PC-SAFT, PC-SAFT, and CPA EoSs across all examined thermodynamic properties and systems were 7.0, 8.2, 22.2, and 30.2, respectively, confirming the robustness of the PρT-SAFT.

Direct calibration using atmospheric particles and performance evaluation of Particle Size Magnifier (PSM) 2.0 for sub-10 nm particle measurements

Abstract. The Particle Size Magnifier is widely used for measuring nano-sized particles. Here we calibrated the newly developed Particle Size Magnifier version 2.0 (PSM 2.0). We used 1–10 nm particles with different compositions, including metal particles, organic particles generated in the laboratory, and atmospheric particles collected in Helsinki and Hyytiälä. A noticeable difference among the calibration curves was observed. Atmospheric particles from Hyytiälä required higher diethylene glycol (DEG) supersaturation to be activated compared to metal particles (standard calibration particles) and other types of particles. This suggests that chemical composition differences introduce measurement uncertainties and highlights the importance of in situ calibration. The size resolution of PSM 2.0 was characterized using metal particles. The maximum size resolution was observed at 2–3 nm. PSM 2.0 was then operated in Hyytiälä for ambient particle measurements in parallel with a Half Mini differential mobility particle sizer (DMPS). During new particle formation (NPF) events, comparable total particle concentrations were observed between the Half Mini DMPS and PSM 2.0 based on Hyytiälä atmospheric particle calibration. Meanwhile, applying the calibration with metal particles to atmospheric measurements caused an overestimation of 3–10 nm particles. In terms of the particle size distributions, similar patterns were observed between the DMPS and PSM when using the calibration of Hyytiälä atmospheric particles. In summary, PSM 2.0 is a powerful instrument for measuring sub-10 nm particles and can achieve more precise particle size distribution measurements with proper calibration.

Fuel Resistance of Firefighting Surfactant Foam Formulations

Aqueous film-forming foam (AFFF) is widely recognized for its excellent fire-extinguishing capabilities, yet the specific roles of its components remain insufficiently understood. AFFF typically consists of fluorocarbon and hydrocarbon surfactants, as well as organic solvents such as diethylene glycol butyl ether (DGBE), which can significantly influence foam performance. This study investigates the effects of surfactant mixtures and the DGBE additive on foam stability and fuel resistance at room temperature and ambient humidity. Static foam ignition experiments were conducted to assess fuel transport through foams using various hydrocarbon fuels, including n-octane, iso-octane, n-heptane, methylcyclohexane, methylcyclopentane, and a mixture of 25% trimethylbenzene with 75% n-heptane. Methylcyclopentane, with its higher vapor pressure and solubility, led to the shortest ignition times, indicating faster fuel transport. The addition of DGBE increased ignition times by a factor of 1.2 to 3.7 for individual surfactants, while the Capstone+Glucopon mixture improved ignition times by a factor of 2.4 to 5.5 compared to the individual surfactants. Further enhancement was observed with Capstone+Glucopon+DGBE, increasing ignition times by a factor of 3 to 7.3 compared to the individual surfactants. Additionally, combining DGBE with surfactant mixtures reduced fuel concentration in the bulk solution by over 60% compared to individual surfactants, significantly enhancing fuel resistance. Interface experiments showed that fuel presence, particularly methylcyclopentane and n-octane, altered the foam structure and accelerated drainage at the foam/fuel interface, impacting foam stability and fuel transport. These findings demonstrate that surfactant mixtures and DGBE-enhanced formulations substantially improve foam stability and fuel resistance.

Development of Latent Fingerprints on Wet, Non-Porous Surfaces by Small Particle Reagent with Zinc Oxide Nanoparticles

Small particle reagent (SPR) technique is a method used for detecting latent fingerprints on wet, non-porous surfaces by suspending nanoparticles in a reagent that binds with fatty acid residues on fingerprints. The small particle reagent technique is particularly effective for detecting latent fingerprints on evidence that has been submerged underwater for prolonged periods. However, due to its reliance on imported reagents, SPR is often expensive and involves a lengthy waiting period. Consequently, many researchers have attempted to develop SPR formulations using easily obtainable, cost-effective, and safe chemicals. In this study, we prepared two new SPR formulations containing zinc oxide nanoparticles mixed with diethylene glycol monoethyl ether. Both formulations used a surfactant composed of two types (sodium tetradecyl sulfate and Tergitol NP-9) for the development of latent fingerprints on wet surfaces. Latent fingerprints were deposited on four different non-porous surfaces, including stainless-steel spoons, glass slides, aluminum foil, and plastic slides. These surfaces were immersed in tap water for 1, 3, 7, 14 and 30 days. The resulting latent fingerprints were analyzed using the Mini Automated Fingerprint Identification System and were shown to produce clear, sharp, and detailed fingerprints on the non-porous surfaces. The best results were found on the surfaces of stainless-steel spoons with both formulations, where minutiae were detectable at more than 40 points even after the surfaces had been immersed in water for up to 30 days. This study provides forensic scientists and crime scene investigators with a faster and safer method for developing latent fingerprints using non-hazardous materials, which could serve as an alternative to conventional formulations.

An Efficient Synthesis of 3,5-Bis-Aminated Pyrazolo[1,5-a]Pyrimidines: Microwave-Assisted Copper Catalyzed C-3 Amination of 5-Amino-3-Bromo-Substituted Precursors

An efficient method has been developed for the rapid production of diverse arrays of 3,5-bis-aminated pyrazolo[1,5-a]pyrimidines. The method utilizes CuI (5 mol%) and carbazole-based ligand L-1 (N-(9H-carbazol-9-yl)-1H-pyrrole-2-carboxamide) (10 mol%) for efficient Ullmann-type coupling of various amines to 5-amino-3-bromopyrazolo[1,5-a]pyrimidine precursors after heating in diethylene glycol (DEG) for only 1 h at 80 °C (microwave heating). 3,5-Bis-aminated products were obtained in good to excellent yields (60–93%, 83% average for 29 examples). 1° and 2° alkylamines, as well as a variety of aryl- or heteroarylamines coupled efficiently, and 1° and 2° alkyl (or aryl) amines at C-5 were well tolerated. The optimized conditions worked well on both the 50 mg and 1.0 g scales and gave products in only two steps from commercially available 3-bromo-5-chloropyrazolo[1,5-a]pyrimidine. Advantages provided by this method include short reaction time, excellent yields, broad substrate scope, and avoidance of toxic reagents commonly utilized for reductive aminations of C-3 NH2 substituted precursors.

Sole-Solvent High-Entropy Electrolyte Realizes Wide-Temperature and High-Voltage Practical Anode-Free Sodium Pouch Cells.

Anode-free sodium batteries (AFSBs) hold great promise for high-density energy storage. However, high-voltage AFSBs, especially those can stably cycle at a wide temperature range are challenging due to the poor electrolyte compatibility toward both the cathode and anode. Herein, high-voltage AFSBs with cycling ability in a wide temperature range (-20-60°C) are realized for the first time via a sole-solvent high-entropy electrolyte based on the diethylene glycol dibutyl ether solvent (D2) and NaPF6 salt. The sole-solvent high-entropy electrolyte with unique solvent-ions effect of strong anion interaction and weak cation solvation enables entropy-driven electrolyte salt disassociation and high-concentration contact ion pairs, thus simultaneously forming stable anion-derived electrode-electrolyte interphases on cathode and anode. Moreover, the wide liquid range of D2 further extends the temperature extremes of the battery. Consequently, ampere-hour (Ah)-level anode-free sodium pouch cells with cyclability in a wide temperature range of -20-60°C are realized. Impressively, the pouch cell achieves a leadingly high cell-level energy density of 209Wh kg-1 and a high capacity retention of 83.1% after 100 cycles at 25°C. This work provides inspirations for designing advanced electrolytes for practical AFSBs.

Dielectric Relaxation Study of Binary Mixture Using Kirkwood Correlation Factor - Time Domain Reflectometry Technique

We have reported, the results of dielectric parameters for Diethylene glycol Monomethyl ether (DGME) -chlorobenzene (CB) binary mixture over the entire range of concentrations in the frequency range from 10MHz-20GHz at different temperatures by time domain reflectometry (TDR) technique. Dielectric parameters viz. dielectric constant (_0 ), relaxation time (τ in ps) were obtained from complex permittivity spectra using nonlinear least squares fit method. Using these parameters excess permittivity (〖_0〗^E ), excess inverse relaxation time(〖1⁄〗^E ), Kirkwood correlation factor 〖(g〗^eff) were determined. On the basis of these parameters, intermolecular interaction and dynamics of molecules at molecular level are predicated. The Kirkwood correlation factor is used to understand the molecular orientation in the mixture. In this paper, the given data provide information regarding solute-solvent interaction.

Assessing the impact of different solvents in the bacterial reverse mutation test.

The bacterial reverse mutation test is essential for identifying the mutagenic potential of chemicals. The solubility of the test substance is vital for achieving the recommended assay concentration. Preferred solvents like dimethyl sulfoxide and water are chosen for their compatibility and historical data. Selecting a compatible solvent with Salmonella typhimurium and Escherichia coli WP2 uvrA strains, considering a maximum cytotoxic concentration or the limit of 5 mg/plate, can be challenging. This study assessed various solvents, including N,N-dimethylformamide, acetone, acetonitrile, ethyl acetate, 95% ethanol, diethylene glycol monomethyl ether, methanol, P-dioxane, tetrahydrofuran, and dimethylacetamide, as alternative solvents in the AMES test. Results showed all solvents, except tetrahydrofuran, were compatible at concentrations up to 100 μL/plate or more, as they did not inhibit S9 enzymes, bacterial growth, or alter bacterial revertant colony counts, making them suitable for the bacterial reverse mutation test.

Permeation Enhancer in Microemulsions and Microemulsion-Based Gels: A Comparison of Diethylene Glycol Monoethyl Ether and Oleyl Alcohol.

Microemulsions have been commonly used with various permeation enhancers to improve permeability through the skin. The purpose of this study was to compare the release and permeation ability of two commonly used permeation enhancers-diethylene glycol monoethyl ether (DGME) and oleyl alcohol-by the changes in oil composition, the addition of a gelling agent, and water content using ibuprofen as a model drug. Four microemulsions were formulated, selection was based on ternary phase diagrams, and physicochemical properties were evaluated. The release and permeation of the microemulsion formulations were performed in vitro by Franz cell studies on a regenerated cellulose membrane and a Strat-M® membrane, respectively, and the amount of ibuprofen permeated and released was analyzed by high-performance liquid chromatography (HPLC). All four microemulsions were compatible with the skin pH, and the average pH ranged from 4.9 to 5.6. The average droplet size of the microemulsions ranged from 119.8 to 153.3 nm. Drug release was significantly the highest from the gel-based microemulsions (59% and 64%, p < 0.05). However, there was a fourfold difference in drug permeation from these gels-a significantly higher permeation from the microemulsion-gel containing oleic acid and oleyl alcohol compared to the DGME formulation. These results indicated that the microemulsion-gel with oleyl alcohol as the permeation enhancer could be a preferable formulation approach for the topical administration of ibuprofen. These results highlight the need for optimization of the microemulsion formulation to confirm the permeation-enhancing effects of chosen permeation enhancers despite being a well-known permeation enhancer.

Depolymerization of Rigid Polyurethane Waste by Catalytic Glycolysis with Diethylene Glycol

Depolymerization of Rigid Polyurethane Waste by Catalytic Glycolysis with Diethylene Glycol

Solubility determination and correlation, solvent effect and thermodynamics of itraconazole in sixteen mono solvents and ternary mixtures of N-methyl-2-pyrrolidone, diethylene glycol monoethyl ether, and ethanol

Solubility determination and correlation, solvent effect and thermodynamics of itraconazole in sixteen mono solvents and ternary mixtures of N-methyl-2-pyrrolidone, diethylene glycol monoethyl ether, and ethanol

Effect of Various Stabilizers on the Characteristics of a Nitrate Esters-Double Base Propellant under Thermal Aging

ABSTRACT The current study examined the stabilizing effect of lignin biopolymer in comparison to traditional 2-nitrodiphenylamine (2-NDPA) and 1,3-Dimethyl-1,3-diphenylurea (C-II) stabilizers on the stability of double-base nitrocellulose (NC)/diethylene glycol dinitrate (DEGDN) propellant during artificial aging (at 338.65 K for 60 days). Various spectroscopic techniques, including Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD), were used, along with traditional stability tests like the Bergmann-Junk (BJ) test and isothermal thermogravimetric analysis (TGA). Experimental results confirmed that FTIR and XRD provided valuable insights into chemical changes during aging. Particularly, lignin-stabilized NC/DEGDN exhibited comparable stability to C-II and 2-NDPA at all stages of aging, as evidenced by the amount of the released nitrous gases measured by BJ test and thermal stability assessed by TGA. Additionally, multivariate data analysis using principal component analysis (PCA) of FTIR spectra successfully differentiated between aged and unaged samples and highlighted trends in stability. Overall, the findings suggest that lignin offers a comparable stabilizing effect for NC/DEGDN propellants relative to traditional stabilizers.

Effect of Chemical Structure and Apparent Density of Rigid Polyurethane Foams on the Properties of Their Chemical Recycling Products.

The aim of this work was to synthesize polyurethane foams based on petrochemical polyols and biopolyols with specific apparent densities (40, 60, 80, 100, and 120 kg/m3), test their properties, glycolyze them, and finally analyze each glycolyzed product. The petroleum-based foams, used as reference foams, and the bio-based foams underwent a series of standard tests to define their properties (the content of closed cells 20-95%, compressive strength 73-1323 kPa, thermal conductivity 24-42 mW/m∙K, brittleness 4.6-82.9%, changes in linear dimensions < 1%, and water absorption < 1%). Taking into account the need for recycling, the foams were shredded and then glycolyzed by diethylene glycol, with the addition of a catalyst in the form of potassium hydroxide. The chemolysis products were analyzed through determination, i.e., the amine and the hydroxyl values, viscosity, and molecular weight. The obtained rebiopolyols had hydroxyl numbers ranging from 476 to 511 mg KOH/g. The type of biopolyol used in the PUR foam systems had a significant impact on the amine number and the viscosity of the obtained rebiopolyol.

Self-assembly of cationic surfactant in choline chloride-based deep eutectic solvents: structural solvation and dynamics.

Deep eutectic solvents (DESs) have gained popularity in various applications due to their improved environmental sustainability and biodegradability. For the present study, several polyhydric alcohols, including ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), and glycerol (Gly), have been used as hydrogen bond donors (HBDs) and choline chloride (ChCl) as a hydrogen bond acceptor (HBA) in a fixed molar ratio to form a homogenous and stable DES. Controlled water mixing into such neat DESs has always been thought to be a quick and efficient method to tune the chemical and thermodynamic properties of DESs. The structural solvation and dynamics of the prepared DESs with the inclusion of water vary from low to high water concentrations that have been examined employing Fourier transform infrared (FT-IR), and proton nuclear magnetic resonance (1H-NMR) spectroscopy. Herein, the micellization behavior of a cationic surfactant, dodecyltrimethylammonium bromide (DTAB), in neat DESs and DES-water mixtures has been demonstrated by using tensiometry, dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS) techniques. Furthermore, it has been observed that DESs exhibit an ample thermodynamic driving force for creating micelles, since they contain an H-bonded nanostructure. However, such self-assembly appears to be very much dependent on DESs, the amount of water, and the surfactant used. A computational simulation approach using a semiempirical method is put forth employing the Gaussian 09 W calculation window in the Gauss View 5.0.9 software package. In addition, this study includes the determination of several optimized descriptors that intend to offer an in-depth examination of the surfactant-DES interactions.

Engineering RAFT Polymers to the Protein-capped Gold Nanoclusters for Developing Fluorescent Polymeric Nanoconjugates.

The synthesis of fluorescent hybrid nanomaterials engineered via the chain-end modification of reversible addition-fragmentation chain-transfer (RAFT) polymers on the surface of bovine serum albumin (BSA) protein-stabilized gold nanoclusters (AuNCs@BSA) is described. Based on the "grafting-to" approach the core-shell structured nanoconjugates AuNCs@BSA/polymer are generated via effective ligation of hydrophilic, and stimuli-responsive polymers. Such nanomaterials are characterized via various microscopic and spectroscopic studies and exhibit their size as ≈5 nm and emission peak at ≈650 nm. Interestingly, the conjugation of thermoresponsive polymer poly(diethylene glycol monomethyl ether methacrylate) (PDEGMA) transformed the nanoconjugates AuNCs@BSA/PDEGMA as dual thermo/pH-responsive nanomaterials.

A Flexible Yet Robust 3D-Hybrid Gel Solid-State Electrolyte Based on Metal-Organic Frameworks for Rechargeable Lithium Metal Batteries.

Compared to traditional liquid electrolytes, solid electrolytes have received widespread attention due to their higher safety. In this work, a vinyl functionalized metal-organic framework porous material (MIL-101(Cr)-NH-Met, noted as MCN-M) is synthesized by postsynthetic modification. A novel three-dimensional hybrid gel composite solid electrolyte (GCSE-P/MCN-M) is successfully prepared via in situ gel reaction of a mixture containing multifunctional hybrid crosslinker (MCN-M), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), ethylene carbonate (EC), diethylene glycol monomethyl ether methacrylate (EGM) and polyethylene (vinylidene fluoridee) (PVDF). Benefiting from the excellent mechanical properties, rich pore structure, and numerous unsaturated metal sites of GCSE-P/MCN-M, our GCSE-P/MCN-M exhibits excellent mechanical modulus (953 MPa), good ionic conductivity (9.3 × 10-4 S cm-1) and wide electrochemical window (4.8 V). In addition, Li/LiFePO4 batteries based on GCSE-P/MCN-M have also demonstrated excellent cycling performance (a high-capacity retention of 87% after 200 cycles at 0.5 C). This work provides a promising approach for developing gel solid-state electrolytes with high ion conduction and excellent safety performance.

High-performance bio-based foam from agricultural waste luffa seed oil polyols

The present study aimed to develop eco-friendly polyurethane viscoelastic foam (PVF) with enhanced tear strength while preserving softness, comfort, and safety by utilizing bio-based polyols derived from luffa seed oil (LSO). Two types of bio-based polyols (PLSO-D and PLSO-M) were synthesized through the epoxidation process using diethylene glycol (DEG) and methanol (MeOH), respectively, for the production of LSO-based polyurethane viscoelastic foams (LSO-PVFs). The analyses revealed that these polyols exhibited high dispersion, appropriate hydroxyl values, and contained by-products such as oligomeric esters of fatty acids that facilitated physical and chemical crosslinking. LSO-PVFs demonstrated a uniform and fine cell structure with abundant open-cells, thick cell walls (55.5–76.6µm), and high apparent density (48.7–50.7kg/m3). Moreover, they exhibited enhanced tensile and tear strength (increasing up to 200% compared to petroleum-based PVFs), lower water absorption, excellent mildew resistance at 10% PLSO substitution. Additionally, these factors endowed LSO-PVFs with low indentation hardness and good bottom support performance, characterized by a compressive deflection coefficient of 2.30–3.54. This approach presents a sustainable alternative for foam production that offers comfort, durability while promoting the value-added utilization of agricultural waste.

Excess properties, intermolecular interaction, and CO2 capture performance of diethylene glycol monomethyl ether + ethylenediamine binary mixed solutions

In this work, the density (ρ) and viscosity (η) values of diethylene glycol monomethyl ether (DEGME) (1) + ethylenediamine (EDA) (2) binary mixed solutions were experimentally measured over the temperature span of 298.15–318.15 K and at a constant pressure of 100.5 kPa. To delve into the physicochemical properties of the binary mixed solutions, the excess properties, including excess molar volume, viscosity deviation, and excess molar activation Gibbs free energy, and thermodynamic values, including activation Gibbs free energy, enthalpy change, entropy change, and activation energy, were systemically calculated. Furthermore, the relationship between mole fraction and temperature was modeled using the Jouyban-Acree (J-A) model and a least squares method. Additionally, the three-body McAllister, the four-body McAllister, the Eyring-Margules, and the Heric viscosity models were employed to establish a relationship between viscosity and mole fraction. The relationship between viscosity and temperature was determined utilizing the Arrhenius equation, and the Redlich-Kister (R-K) polynomial was applied to fit the excess molar volume, viscosity deviation, and excess molar activation Gibbs free energy values of the binary mixed solutions. To further validate the intermolecular interactions within the binary mixed solutions, Raman, UV, and 1H NMR spectroscopic analyses, and density-functional theory (DFT) calculations were also conducted. These comprehensive analyses collectively confirmed the presence of significant intermolecular hydrogen bonds (IHBs) between the DEGME and EDA molecules, which are characterized as the –OH⋯NH2– interaction. Ultimately, the CO2 absorption capacity of the binary mixed solutions was examined, revealing that diethylene glycol monomethyl ether (DEGME) (1) + ethylenediamine (EDA) (2) binary mixed solutions owned superior CO2 absorption efficiency, thus offering a promising approach for CO2 capture.

Electropolishing of Magnesium and Its Alloys in Highly Safe Sodium Chloride/Glycol Solutions

Magnesium and its alloys are expected to be used in various engineering fields, such as automobiles, trains, and electronic product enclosures due to their lightness and mechanical properties. Electropolishing of magnesium surfaces is an important technique for fundamental research works and industrial applications, and perchloric acid or nitric acid is typically used for electropolishing. However, these acids are highly reactive and hazardous, thus the usage should be avoided in the industrial application processes. In this study, we demonstrated a highly safe electropolishing process of magnesium using a novel sodium chloride/glycol solution.High-purity magnesium plates (99.95 wt%, 1 mm thick) were used as the starting materials. The specimens were ultrasonically degreased in ethanol for 10 min. The magnesium specimen as the anode and a platinum plate as the cathode were immersed in four types of glycol solutions including 0.5 M NaCl/ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), and tetraethylene glycol (TeEG) solutions at 278-308 K, and linear sweep voltammetry (0.1 Vs-1) and constant voltage electrolysis (25-100 V) were carried out. After electrolysis, the surface of the specimens was examined by stereo microscopy (SM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The regular reflectance from the magnesium surfaces was measured using a spectrophotometer. Two types of industrial magnesium alloys including Mg-Al alloy, AZ31, and Mg-Li alloy, LZ91, were also used for electrolysis.As the voltage-current curves were measured by linear sweep voltammetry of the pure magnesium specimen in four types of glycol solutions, clear diffusion limiting currents were obtained after the initial current increases. We found that the unevenness of the magnesium specimens decreased by constant voltage electrolysis at appropriate applied voltages in NaCl/DEG and NaCl/TeEG solutions. Figure 1a shows the surface appearances of pure magnesium, LZ91, and AZ31 after constant voltage electrolysis at 50 V in NaCl/DEG solution for 60 min. The pure magnesium specimen and LZ91 alloy were successfully electropolished by constant voltage electrolysis and mirror-finished surfaces were obtained. On the other hand, the AZ31 alloy exhibited a nonuniform appearance with the coexisting of metallic luster and brownish regions, although a mirror-finished surface was obtained. The difference of the electropolishing behaviors between LZ91 and AZ31 alloys may be due to the metallographic structure such as the solid solution and intermetallic compound. Three-dimensional magnesium specimens possessing the curved and spiral structures could also be electropolished by constant voltage electrolysis in NaCl/DEG (Fig. 1b). Figure 1

Effects of Polymer Side Chains on Ion Transport Properties of Gel Electrolytes Containing High Concentration Li Salt Solution

Highly concentrated Li salt electrolyte solutions have attracted attention recently due to the unique physicochemical and electrochemical properties.1 Recently, our group reported that highly concentrated Li salt/sulfolane electrolytes exhibit Li+ ion hopping conduction mechanism.2 Gel electrolytes, which incorporate liquid electrolytes within polymer network generally maintain ion transport properties derived from liquid electrolytes. The gelation of liquid electrolytes can prevent the leakage of liquids and improve the safety of batteries. However, certain gel electrolytes containing high concentration Li salt solution have been reported that the ion transport properties can be affected by the participation of the polymer matrix in the solvation structure.3 In this study, we focused on the effects of polymer side chains on ion transport properties of gels. We prepared novel gel electrolytes using polymers with different side chains as a polymer matrix containing high concentration Li salt/sulfolane solutions. Gel electrolytes incorporating lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and sulfolane (SL) at 1:3 molar ratio, which exhibits a high Li+ ion transference number (t Li+ ), were prepared by free radical polymerization using four types of methacrylate monomers (methyl methacrylate: MMA, propyl methacrylate: PMA, 2,2,3,3-tetrafluoropropyl methacrylate: TFPMA, diethylene glycol monomethyl ether methacrylate: DEGMA). Ionic conductivity and of PMMA gel were comparable to those of PPMA gel with extended alkyl side chains, while in PDEGMA gel with multiple coordination sites for Li+ showed lower t Li+ because Li+ ions were trapped by the ether moiety of the side chain. On the other hand, PTFPMA gel with partially fluorinated propyl side chains showed a higher t Li+ . The self-diffusion coefficients of Li+, TFSA−, and SL in PTFPMA gel measured with pulsed field gradient (PFG) NMR suggested lower diffusivity of TFSA− compared to that in PPMA gel. Moreover, 19F NMR revealed that the signal derived from TFSA− shifted to downfield side in PPMA gel and upfield shift in PTFPMA gel compared to that in the liquid electrolyte of [LiTFSA]/[SL] =1:3, indicating a change of solvation structure due to the polymer side chain. Finally, we demonstrated rate capability tests for gel electrolytes with LiCoO2/Li cells and found that the cell with PTFPMA gel having high t Li+ exhibited better rate performance than one with PPMA gel. Acknowledgements This study was partially supported by Japan Science and Technology Agency (JST) GteX Program (Grant No. JPMJGX23S0) and JSPS KAKENHI (Grant No. 22H00340) from the Japan Society for the Promotion of Science (JSPS). References Yamada and A. Yamada, Review—Superconcentrated Electrolytes for Lithium Batteries, J. Electrochem. Soc., 2015, 162, A2406–A2423.Dokko, D. Watanabe, Y. Ugata, M. L. Thomas, S. Tsuzuki, W. Shinoda, K. Hashimoto, K. Ueno, Y. Umebayashi and M. Watanabe, Direct Evidence for Li Ion Hopping Conduction in Highly Concentrated Sulfolane-Based Liquid Electrolytes, J. Phys. Chem. B, 2018, 122, 10736–10745.Tasaki, Y. Ugata, K. Hashimoto, H. Kokubo, K. Ueno, M. Watanabe and K. Dokko, Tetra-arm poly(ethylene glycol) gels with highly concentrated sulfolane-based electrolytes exhibiting high Li-ion transference numbers, Phys. Chem. Chem. Phys., 2023, 25, 17793–17797.