Poly Ethylene Glycol Dimethyl Ether Research Articles

Preparation of Pebax based ternary mixed matrix membranes for enhancing CO2 transport and separation

As a type of material for membrane separation in carbon capture technology, mixed matrix membranes (MMMs) have the advantages of simple processing and excellent gas separation performance and have great research prospects. However, the affinity between organic matrix and inorganic fillers is usually poor, and microphase separation occurs at the interface. At the same time, as the filler content increases, the filler particles will aggregate, leading to non-selective defects in the homogeneous membrane and reducing the gas separation performance of MMMs. Herein, the strategy of adding a third component was adopted. Small molecule polyethylene glycol dimethyl ether (PEGDME) was introduced into the Pebax/NH2-MIL-101 membrane to prepare a ternary mixed matrix membrane Pebax/PEGDME/NH2-MIL-101. Adding small molecules as the third component optimized the membrane structure by utilizing the interaction between the third component, inorganic fillers, and polymer matrix, effectively improving the physical microenvironment of gas separation. At the same time, NH2-MIL-101 was modified to PEI-MIL-101, further improving the performance of the mixed matrix membrane. The CO2 permeability of the Pebax/PEGDME/NH2-MIL-101 ternary mixed matrix membrane reached 313 Barrer, and the CO2/N2 selectivity reached 47.7. The CO2 permeability coefficient of Pebax/PEGDME/PEI-MIL-101 membrane reached 286 Barrer, and the CO2/N2 selectivity coefficient reached 54.2. This work provides new ideas for optimizing the gas separation performance of mixed matrix membranes.

Achieving High‐Performance in Zinc Hybrid Capacitors with Zn(TFSI)2/PEGDME Molecular Crowding Electrolytes

Aqueous Zinc‐hybrid capacitors (ZHCs) are gaining attention for their high‐safety, low cost, easy maintenance, high‐power, and longevity. Despite various strategies to mitigate dendrites, corrosion, and HER, practical application remains challenging. Here, we utilize an advanced polyethylene glycol dimethyl ether (PEGDME)‐based molecular crowding electrolyte (MCE) to significantly enhance performance of ZHCs. Our MCE offers a wider electrochemical stability window (2.7 V), low HER activity, and superior Zn anti‐corrosion properties due to reduced water activity compared to conventional electrolyte. This results in higher coulombic efficiencies (98–100%) at various areal capacities and current densities, and longer longevity of Zn//Cu and Zn//Zn symmetric cells with MCE compared to conventional and water‐in‐salt electrolytes. The Zn/MCE/AC displays an enhanced voltage window (~2 V), achieving the highest capacitance (281 F/g), competitive energy density (138 Wh/kg), low self‐discharge, and excellent cyclability (19100 cycles at 1 A/g with 100% capacity retention), indicating that MCE is a promising approach for practical energy storage applications

Dilute aqueous hybrid electrolyte endows a high-voltage window for supercapacitors

Developing aqueous electrolyte with wide electrochemical stability window (ESW) is one of the key technologies to boosting the energy density of aqueous electrochemical double-layer capacitors (EDLCs). However, expanding the ESW using super-concentrated electrolytes comes at the expense of cost, ionic conductivity and the mass density of the device. Herein, we selected a cost-effective and environmentally friendly molecular crowding agent, polyethylene glycol dimethyl ether (PEGDME-250), as the electrolyte additive designed to achieve high ESW at low salt concentrations. First, PEGDME can reduces the activity of water and increases the ESW of the electrolyte by forming hydrogen bonds with free water molecule. In addition, PEGDME does not have the interaction between terminal groups compared to conventional polyethylene glycols (PEG), which helps to reduce the viscosity and improve the ionic conductivity of the electrolyte. By adjusting the composition of the electrolyte, the optimal electrolyte with a high ESW of 2.96 V was achieved with the formula of 3 m NaClO4-25 % H2O-75 % PEGDME. The EDLCs assembled with this diluted aqueous electrolyte and YP-50 F electrodes presents a high operational voltage window of 2.4 V and outstanding cycle stability (>10000 cycles), and maintains excellent rate performance in a temperature range of −10–35 ℃.

Realization of Enhanced Interfacial Lithium-Ion Transfer in Composite Polymer Electrolytes via Grafting Oligo-PEG Molecular Brushes on Silica-Coated Nanofibers for All-Solid-State Lithium Metal Batteries.

Polyether-based polymer electrolytes are attractive but still challenging for high-energy-density solid-state lithium metal batteries due to their limited Li-ion conductivity at room temperature. Herein, an oligomeric polyethylene glycol methyl ether methacrylate (PEGMEM)-modified silica-coated polyimide fibrous scaffold (PINF@PEGMEM-SiO2) was introduced in polyethylene glycol dimethyl ether (PEGDME) to enhance the Li-ion transportation at room temperature. PINF@PEGMEM-SiO2 was developed to build a continuous and interconnected interface for continuous Li-ion transportation in bulk. The carbonyl groups (C═O) of PEGMEM on SiO2 can promote the dissociation of lithium salts and enhance the migration of free Li ions at the interface. The same -C-C-O- unit contained in both PEGMEM and PEGDME ensures the compatibility of PEGMEM at the interface and PEGDME in the bulk. The prepared PEGDME-based polymer electrolyte exhibits a high ionic conductivity of 1.14 × 10-4 S cm-1 at 25 °C and an improved Li-ion transference number of 0.41. Furthermore, LiFePO4/Li and LiNi0.8Co0.1Mn0.1O2/Li cells with excellent cyclability and rate capability at ambient temperature are obtained.

A thermostable ionic liquid-methacrylate-based polymer electrolyte for energy storage application

In recent years, gel polymer electrolytes (GPEs) incorporating ionic liquids (ILs) have been explored extensively for lithium-ion batteries due to their favourable thermal stability and high ionic conductivity. Gel polymer electrolytes can also improve the safety of lithium-ion batteries by eliminating the flammable organic solvents which are often used in traditional electrolyte systems. Herein, we report an efficient synthesis of a thermostable ionic liquid-methacrylate-based polymer gel electrolyte via a photo-initiated phase separation (PIPS) process in an inert environment. Anionic liquid phase of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI), coupled with a low molecular weight polyethylene glycol dimethyl ether (PEGDME), was combined with a solid phase of bisphenol A ethoxylate dimethacrylate (BEMA) at varying solid to liquid ratios to produce a thermally stable gel electrolyte. The highest ionic conductivity of 1.9 × 10−3 S cm−1 (at 30 °C) was achieved for the electrolyte with a solid-to-liquid ratio of 1:3 by weight. The Lithium metal cells utilizing these electrolytes and LiFePO4 as cathode active material exhibited the initial discharge capacity of 144 mAh g−1 with capacity retention of 85 % over 100 cycles in ambient temperature. The thermal stability of the cells was significantly improved upon increasing the EMIMTFSI content. This study illustrates the potential application of the IL-methacrylate gel polymer electrolyte system in enhancing the safety of Li-ion batteries through careful tuning of the composition. Their versatile properties also make them suitable for quasi-solid-state batteries with high energy density and safety.

3D Printable Multifunctional Electrochemical Nano‐Doped Biofilament

AbstractFused deposition modeling (FDM) represents a state‐of‐the‐art 3D printing technology that holds great promise in the field of electrochemistry as a fast, in‐house, and digital fabrication method of sustainable sensors. Despite the progress in FDM, existing practical 3D printed sensors still require post‐printing treatment to improve their operational features, either through (electro)chemical surface activation or surface modification with external functional materials. Herein, a novel lab‐made conductive biofilament with integrated two different types of metallic nanoparticles (NPs) for the 3D printing of ready‐to‐use and multiplexed electrochemical sensors is introduced. The filament is composed of biodegradable polylactic acid as a base, polyethylene glycol dimethyl ether as a plasticizer, carbon black as a conductive filler, and nanopowder oxides of bismuth and copper as integrated functional precursor materials. The as‐printed sensors serve as multifunctional transducers for the direct and sensitive determinations of several analytes, by exploiting the different properties of the two co‐existing NPs. Particularly, heavy metals (such as lead, and cadmium) are voltammetrically quantified by amalgamation with BiNPs electrogenerated from Bi2O3, while biomarkers (such as glucose, and uric acid) are determined in enzymatic‐free modes. Determination of glucose takes advantage of the electrocatalytic properties of CuO, while uric acid is directly oxidized at the sensor.

In‐Situ Polymerization Confined PEGDME‐Based Composite Quasi‐Solid‐State Electrolytes for Lithium Metal Batteries

AbstractSolid‐state lithium metal batteries are under development for higher energy density and better safety. A key is to develop new electrolyte systems that are readily processible and capable to improve electrochemical cycling stability. In this study, A quasi‐solid‐state composite electrolyte based on low‐molecular‐weight polyethylene glycol dimethyl ether (PEGDME) in situ confined within polymerized methyl methacrylate (PMMA) backbone is designed and presented. The new design of the polymer matrix, together with Li+‐conducting ceramic fillers and appropriate lithium salts, has satisfactory Li‐ionic conductivity (1.1 × 10−4 S cm−1 at 30 C and 1.0 × 10−3 S cm−1 at 80 °C), good electrochemical stability (>4.7 V vs Li+/Li), and high compatibility with lithium metal anode, enabling room‐temperature operation and stable long‐term cycling of both Li||Li symmetric cells and lithium‐metal full cells (including LiFePO4 or LiCoO2 cathode). This work can extend the design boundaries of composite electrolytes meaningfully, and the idea of in situ polymerization limiting applies to almost all low‐molecular‐weight polymers, high‐molecular‐weight backbones, ceramic fillers, lithium salts, and additives in future development of room‐temperature solid‐state lithium metal batteries.

Screening of toluene absorbents based on molecular simulation and experimental investigation on novel compound solvents

This work aims to screen out absorbents with excellent performance to control toluene pollution. Based on density functional theory (DFT), this article calculated the binding energy between toluene and organic solvents molecules with specific functional groups, and comprehensively examined the physical and chemical properties of the solvents to screen out suitable toluene absorbents. The computational binding energy and the experimental absorption efficiency have the same change tendency, that is, the value of the binding energy determines the ability of the solvents to absorb toluene. Pentaethylene glycol dimethyl ether (PGDE), 1-methyl-2-pyrrolidinone (NMP), dioctyl phthalate (DOP) and sulfolane (SUL) were initially selected as toluene absorbents. Atoms in molecules (AIM) analysis, reduced density gradient (RDG) analysis and symmetry-adapted perturbation theory (SAPT) analysis were used to explore the microscopic mechanism of toluene absorption by four organic solvents. The results show that the interactions between organic solvents and toluene are weak interactions dominated by dispersion attraction. The experiment used polyethylene glycol dimethyl ether (NHD) with very low volatility as the main solvent, which is a polymer containing the main component PGDE, and compounded it with NMP, DOP, and SUL respectively. The absorption experiment investigated the efficiency of compound solvents with different mass fractions of compound components on toluene under the conditions of normal pressure, liquid-to-gas ratio 2.5 L/m3, gas flow rate 4 L/min, temperature 30°C, inlet concentration approximately 6000 mg/m3, and packing height 60 cm. The results show that the toluene absorption efficiency of the three compound solvents is more than 91%. Considering the absorption performance, consumption and stability of the solvent, NHD-SUL solvent (20 wt.% SUL) was finally selected as the new compound solvent. The new compound solvent regenerated lean solution still maintains a good absorption efficiency of 90% after 13 desorption cycles. Theoretical and experimental research are of great significance for the future treatment of exhaust gas pollution.

Energy-efficient biphasic solvents for industrial CO2 capture: Absorption mechanism and stability characteristics

The traditional CO2 capture process represented by monoethanolamine has excessive energy consumption, serious oxidative degradation and metal corrosion, which limits its potential for large-scale industrial applications. This study produced a highly effective biphasic 3-amino-1-propanol (MPA)–polyethylene glycol dimethyl ether (NHD)–H2O absorbent with easy modulation of phase separation and low levels of oxidative degradation and metal corrosion. The principal absorbent was MPA, and NHD served as the phase separation solvent. NHD's solvent effect decreased the energy barrier preventing MPA from forming zwitterions (MPA+COO−) and carbamate, thus promoting chemical absorption. The large polarity difference between the reaction products and NHD triggered phase separation, producing a low-polarity CO2-lean phase and a high-polarity CO2-rich phase; 97.41% of the absorbed CO2 accumulated in 43.7% of the CO2-rich phase solution. The sensible heat and latent heat of the MPA–NHD–H2O absorbent were relatively low because of the low saturation vapor pressure, high vaporization enthalpy, and excellent phase separation performance of NHD. The regeneration energy was as low as 2.66 GJ/t CO2, which was 30% less than that for monoethanolamine. Additionally, the oxidative degradation rate for the proposed absorbent was only 10.7% of that for monoethanolamine. This study provides a theoretical reference for application of the MPA–NHD–H2O biphasic absorbent.

A Molecule Crowding Strategy to Stabilize Aqueous Sodium‐Ion Batteries

AbstractAqueous sodium‐ion batteries (ASIBs) have recently emerged as a compelling choice for large‐scale energy storage when considering their safe operational characteristics and cost‐effectiveness. Nonetheless, the inadequate electrochemical stability window (ESW) of water (1.23 V) and severe dissolution of electrodes in aqueous electrolytes have proven bottlenecks to enabling high energy density and long lifespan of ASIBs. Here, a molecular crowding electrolyte is introduced, featuring nonflammable polyethylene glycol dimethyl ether (PED) as a crowding agent and a hydrogen bond receptor to further diminish the water activity. The 4.5 m (mol kg−1) NaClO4‐4 wt% H2O‐96 wt% PED electrolyte displayed an impressive ESW of 3.4 V, all while maintaining a moderate salt concentration of 4.5 m. Meanwhile, this electrolyte demonstrated substantial mitigation of vanadium dissolution in Na3V2(PO4)3. Consequently, in a comprehensive evaluation, the aqueous NaTi2(PO4)3||Na3V2(PO4)3 full cell exhibited an energy density of 47 Wh kg−1 at 1 C with a 74% retention after 100 cycles, and displayed negligible capacity decay (≈0.014% per cycle) at 5 C in 1000 cycles with high average coulombic efficiency of 99.8%. This work offers a universal strategy for the design of aqueous electrolytes with wide ESW and the ability to effectively suppress vanadium dissolution.

Microstructural investigation of the cooperative gelation of syndiotactic polystyrene and high MW polyethylene glycol di-methyl ether in common solution in THF

The gelation of syndiotactic polystyrene (sPS) in THF in the presence of high molecular weight PEGDME was investigated in detail using contrast-matching SANS complemented by in situ FTIR. Using the contrast-matching method, the scattering contribution of each of the two polymers in the common solution in THF at high temperature (110 °C), in the single-coil conformational state and in the gelation state of sPS (below 40 °C and down to 10 °C) was observed, and the structural characterization of the polymer coils and the junction structures of the gel was obtained. The local scale conformation of the two types of polymer molecules in the different regimes was additionally monitored by FTIR. The gelation and melting temperatures were determined by DSC. sPS changes from the amorphous coil to the helical TTGG conformation when the gelation temperature is passed, forming fibrillar morphologies with a local 2D aspect due to cooperative interactions with the solvent molecules. These are the junction structures of the large-scale network morphology of the gel. The high molecular weight PEGDME transitions from the amorphous coil to an elongated amorphous conformation and incorporates into the fibrillar morphology together with the sPS during the gelation process. High MW PEGDME alone in THF forms a "house of cards" gel consisting of stacked lamellar structures on a smaller length scale, as shown by the scattering data. Thus, in the presence of sPS, smaller and softer structures appear as a result of a cooperative gelation process controlled by sPS. Incorporation of high MW PEGDME into these aggregates leads to polymer nanocomposites that can render the sPS hydrophilic, a topic that should be the focus of future structural and morphological studies.

Techno-economic analysis of solvent-based biogas upgrading technologies for vehicular biomethane production: A case study in Prados de la Montaña landfill, Mexico City

This study examines the feasibility of utilizing biogas from the Prados de la Montaña landfill (PML) in Mexico City to produce vehicular biomethane. Five solvent-based biogas upgrading technologies are analyzed: water scrubbing (WS), propylene carbonate (PC), dimethyl ether of polyethylene glycol (DPEG), monoethanolamine solution (MEA), and potassium carbonate solution (K2CO3). Process modeling and economic analysis are conducted, focusing on the levelized cost of energy (LCOE) as a comparative indicator. The results indicate that the quality and production capacity of biomethane are comparable across all evaluated technologies. The carbon capture system, which significantly impacts the LCOE, represents the largest component cost of the biogas upgrading plant. Among the case studies, the PC solvent demonstrates the most favorable economic performance ($14.5/MMBTU), followed by the solvents K2CO3, DPEG, and WS, which exhibit similar LCOE values ($17.1–17.5/MMBTU). Conversely, the MEA solvent exhibits the highest cost ($20.3/MMBTU). While these LCOEs exceed the historical average cost of natural gas in the market, the PC solvent remains competitive at a carbon tax price ≥ $9.6/tCO2eq. In conclusion, the commercial viability of producing vehicular biomethane at PML using these technologies is primarily dependent on the projected price of imported natural gas and the carbon tax.

Thermodynamic studies of solute–solute and solute–solvent interactions in ternary aqueous systems containing {betaine + PEGDME250} and {betaine + K3PO4 or K2HPO4} at 298.15 K

In this work, to evaluate solute–solute, solute–solvent and phase separation in aqueous systems containing {betaine + poly ethylene glycol dimethyl ether with molar mass 250 g mol−1 (PEGDME250)}, {betaine + K3PO4} and {betaine + K2HPO4}, first water activity measurements were made at 298.15 K and atmospheric pressure using the isopiestic technique. The water iso-activity lines of these three systems were obtained which have positive deviations from the semi-ideal solutions. This suggests that betaine-polymer and betaine-K3PO4 or betaine-K2HPO4 interactions are unfavorable; and these mixtures may form aqueous two-phase systems (ATPSs) at certain concentrations. Indeed the formation of ATPSs was observed experimentally. Then, osmotic coefficient values were calculated using the obtained water activity data; and, using the polynomial method the solute activity coefficients were determined. Using these activity coefficients, the transfer Gibbs energy (Delta {G}_{tr}^{i}) values were calculated for the transfer of betaine from aqueous binary to ternary systems consisting polymer (PEGDME250) or salts (K3PO4 and K2HPO4). The obtained positive Delta {G}_{tr}^{i} values again indicated that there is unfavorable interaction between betaine and these solutes. Finally, the volumetric and ultrasonic studies were made on these systems to examine the evidence for the nature of interactions between betaine and the studied salts or polymer.

Cryogenic CO2 capture from oxy-combustion flue gas by a hybrid distillation + physical absorption process

Hybrid flowsheets are defined, in the context of process intensification, as alternatives suitable for replacing energy-intensive separation methods through the combination of more than one unit operation. Given the undoubted importance of carbon capture, utilization, and storage (CCUS) in the next decades in the path to net-zero emissions and even negative emissions scenarios, this work focuses on CO2 capture from an oxy-combustion flue gas by means of a distillation-based hybrid process that avoids CO2 freeze-out, which is capable of delivering a liquid CO2-rich stream that can in principle be pumped to transport pressures with lower energy consumption in comparison to conventional post-combustion CO2 capture processes based on chemical absorption. A distillation-based process and a hybrid distillation + physical absorption process have been studied based on simulations in Aspen Hysys® V11 using the Peng-Robinson Equation of State and the “Acid Gas – Physical Solvents” thermodynamic property package. Firstly, a CO2 capture process based on cryogenic distillation has been proposed and a sensitivity analysis on the operating pressure and specified CO2 recovery has been performed in order to determine the most convenient configuration, balancing capital and operating costs. Then, a hybrid capture process has been proposed and analyzed, where cryogenic distillation is the bulk removal step and physical absorption into a mixture of homologues of the dimethylether of polyethylene glycol (DEPG) is the finishing step. Energy and economic analyses have shown that the hybrid process, delivering a CO2 product respecting the stringent purity requirement on the oxygen content for application for Enhanced Oil Recovery (EOR) and in the food industry is less energy intensive than the standalone cryogenic distillation, though it is characterized by higher capital costs.

Vapor-liquid equilibria behavior of binary and ternary polymer-polymer alcoholic solutions

Aiming at scrutinizing the soluting effect occurring in alcoholic systems composed of two polymers (polymer 1 + polymer 2 + alcohol systems), the systematic isopiestic measurements of the vapor-liquid equilibrium behavior were carried out on some ternary ethanolic, propanolic, and butanolic solutions of two polymers at 298.1 K. In order to cover a wide range of hydrophilic and lipophilic behaviors, the polymers: polyethylene glycol 400 (PEG400), polyethylene glycol dimethyl ether 250 (PEGDME250), polyethylene glycol dimethyl ether 500 (PEGDME500), polypropylene glycol 400 (PPG400), polypropylene glycol 1000 (PPG1000) and polyvinylpyrrolidone 10000 (PVP10000) were selected. Deviations of iso-solvent activity lines from the linear isopiestic relation (LIR) were considered as a benchmark to identify the soluting effects of polymer 1 on polymer 2 in these systems. It was found that all the investigated solutions containing PVP show the soluting-in effect (positive deviation from the linear isopiestic relation), and the other solutions including PEG-PPG, PEG-PEGDME, PPG-PEGDME, PEG-PEG, PPG-PPG and PEGDME-PEGDME show the semi-ideal (linear isopiestic relation) behavior. The effect of alcohol type, polymer type, and polymer molar mass on the solvent activity of binary alcohol-polymer solutions as well as on the deviations of ternary systems from the semi-ideal behavior was studied. Finally, the obtained solvent activity data were used to calculate the vapor pressure of solutions as a function of concentration, and the segment-based local composition Wilson model was used to correlate the experimental solvent activity data.

Optimization and Comparison of CO<sub>2</sub> Capture Process Using DEPG and Methanol Solvents

This study focus is on the physical solvent-based CO2 capture process from an integrated Gasification Combined Cycle (IGCC) power plant, followed by a comparison of Dimethyl ether of polyethylene glycol (DEPG) solvent and methanol solvent, which is based on traditional technology and has a 95% CO2 purification requirement. After achieving the optimal condition, we would compare which solvents are suitable for this system. This procedure was simulated in Aspen HYSYS. Additionally, this study examined the effects of factors that provide the CO2 capture cost per ton ($/tCO2 captured). The response surface approach is used to get the optimal result. In the case of the optimal condition of DEPG solvent, the inlet temperature of fuel gas is – 2 °C, the stripper of inlet temperature is at 67 °C, the pressure of the absorber is at 2,994 kPa, and the stage of absorber appears to be 12 stages. As a result, the lowest DEPG solvent process cost is $189.63 per ton of CO2 collected. The minimum cost of CO2 capture under the optimal condition of methanol solvent, where the temperature of the absorbent and fuel gas is – 8 and – 20 °C, the stripper inlet temperature appears to be at – 6 °C, and the concentration of the absorbent is 88.85 wt.% in methanol solvent, is then $19.21 per ton of CO2 captured.

In-situ constructing of dual bifunctional interfacial layers of garnet-type Li6.4La3Zr1.4Ta0.6O12 solid electrolyte towards long-cycle stability for flexible solid metal lithium batteries

Lithium metal batteries are used widely because of their high security and high energy density. However, the solid electrolytes and electrodes have incompatible interfaces, and the lithium anode is also hindered by dendrite growth. Herein, a bifunctional stable electrode interface layer is constructed by in-situ polymerization of polyester-based monomers and organic solvent, revealing the strong correlation between cathode electrolyte interphase (CEI) on cathode and solid electrolyte interface (SEI) on Li metal anode. The sandwich-like composite electrolyte prepared with garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) active fillers and polymer electrolyte composed of (poly(ethylene glycol) dimethyl ether (PEGDME), trimethylolpropane trimethyllacrylate (TMPTMA), 1,6-hexanediol diacrylate (HDDA)(named as P(PF)1TH) exhibits excellent flexibility, wide electrochemical window, and good thermal stability. Moreover, P(PF)1TH-10%LLZTO electrolyte has satisfactory ionic conductivity (1.42 × 10−3) at 50 °C and high Li+ transference number (0.547) at 25 °C, and symmetrical Li|P(PF)1TH-10%LLZTO|Li cells can run stably for more than 1000 h at 0.1 mA cm−2 at 50 °C. The assembled LiFePO4(LEP)|P(PF)1TH-10%LLZTO |Li cell shows high discharge capacity of 139.9/122.8 mAh g−1 with capacity retain of 90.64%/97.96% after 200 cycles at 1C/2C. This work introduces a dual functional interface layer between electrolyte and electrode through in-situ polymerization, which brings a new idea for electrode interface compatibility.

Plasticization, Antiplasticization, and Fragility in Blends of Polyvinyl Butyral and Polyethylene Glycol Dimethyl Ether

AbstractBlends of polyvinyl butyral (PVB) and polyethylene glycol dimethyl ether (PEGDME) with low molecular weight (= 250 g mol−1) show two calorimetric (for PEGDME content higher than 11% by weight) and mechanical glass transitions. Their substantial changes in the relative content of the two components are explained by considering the self‐concentrations of both polymers determined by the connectivity of their own chains. Increasing content of PEGDME lower the glass transition temperature Tg of PVB (the component with the highest Tg) by about 100 K, also causing a progressive and significant increase of its fragility (following the Angell's strong/fragile liquids classification scheme). Strengthening of polymer blends is observed in the fully glassy region, quite below the Tg's of both the components, with the storage modulus E′ becoming more than a factor 2 higher than that of neat PVB. The progressive increase of E′, without any change of slope, points to structural homogeneity of blends determined by compatibility of components, as a result of interchain interactions activated by the polar groups of both polymers. The present results reveal that PEGDME plasticizes PVB when the blend is in the fully rubbery state while acting as an anti‐plasticizer in the fully glassy state.

Room-Temperature Solid-State Polymer Electrolyte in Li-LiFePO4 , Li-S and Li-O2 Batteries.

A solid polymer electrolyte has been developed and employed in lithium-metal batteries of relevant interest. The material includes crystalline poly(ethylene glycol)dimethyl ether (PEGDME), LiTFSI and LiNO3 salts, and a SiO2 ceramic filler. The electrolyte shows ionic conductivity more than 10-4 S cm-1 at room temperature and approaching 10-3 S cm-1 at 60 °C, a Li+ -transference number exceeding 0.3, electrochemical stability from 0 to 4.4 V vs. Li+ /Li, lithium stripping/deposition overvoltage below 0.08 V, and electrode/electrolyte interphase resistance of 400 Ω. Thermogravimetry indicates that the electrolyte stands up to 200 °C without significant weight loss, while FTIR spectroscopy suggests that the LiTFSI conducting salt dissolves in the polymer. The electrolyte is used in solid-state cells with various cathodes, including LiFePO4 olivine exploiting the Li-insertion, sulfur-carbon composite operating through Li conversion, and an oxygen electrode in which reduction and evolution reactions (i. e., ORR/OER) evolve on a carbon-coated gas diffusion layer (GDL). The cells operate reversibly at room temperature with a capacity of 140 mA h g-1 at 3.4 V for LiFePO4 , 400 mA h g-1 at 2 V for sulfur electrode, and 500 mA h g-1 at 2.5 V for oxygen. The results suggest that the electrolyte could be applied in room-temperature solid polymer cells.

Water hydration of polyethylene glycol dimethyl ether.

In this work, GHz and THz complex dielectric spectra of a polyethylene glycol dimethyl ether (2000 g/mol) aqueous solution were studied. The reorientation relaxation of water in this kind of macro-amphiphilic molecule solution can be well described by three Debye models, including under-coordinated water, bulk-like water [water molecules in a tetrahedral hydrogen bond network (bulk water) and bulk water molecules affected by hydrophobic groups], and slow hydrating water (water molecules donating hydrogen bonds to hydrophilic ether groups). The reorientation relaxation timescales of bulk-like water and slow hydration water both show increases with concentration from 9.8 to 26.7ps and from 46.9 to 100.1ps, respectively. By estimating the ratios of the dipole moment of slow hydration water to the dipole moment of bulk-like water, we calculated the experimental Kirkwood factors of bulk-like and slow hydrating water. The experimental Kirkwood factor of bulk-like water increased from 3.17 to 3.44 with concentrations, while the experimental Kirkwood factor of slow hydrating water roughly remained constant at 4.13 from concentrations of 15%-60%. The estimated water molecule numbers of three water components around monomers also confirm our sorting for water components.