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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Influence of linkage chemistry and side-chain polarity on Ion 2 transport in click-functionalized polymerized ionic liquids.

Post-polymerization functionalization offers precise molecular weight control and enables the high-throughput investigation of structure−property relationships in polymer research. However, post-polymerization functionalization strategies often introduce additional linkage chemistry, and its role in the physical properties of polymerized ionic liquids (PILs) has yet to be explored. In this work, a series of PILs were synthesized using Cu(I)-catalyzed azide−alkyne cycloaddition (CuAAC), with comparison made to N-alkylation substitution chemistry. The triazole ring introduced by CuAAC chemistry was found to induce extensive ion aggregation and deteriorate ion transport. The impact of linkage chemistry on ion transport can be alleviated by incorporating polar ethylene glycol spacers in the side chain, achieving an ionic conductivity of 2.1 × 10−4 S/cm at 30 °C. Furthermore, the effect of polar spacer placement was explored, revealing that overall side-chain polarity, rather than polarity in the vicinity of the ionic group, governs ion aggregation and ion transport in PILs.

Shan, Naisong↗
DOE OSTI2023

Microwave Regeneration and Thermal and Oxidative Stability of Imidazolium Cyanopyrrolide Ionic Liquid for Direct Air Capture of Carbon Dioxide

Abstract Understanding the oxidative and thermal degradation of CO 2 sorbents is essential for assessing long‐term sorbent stability in direct air capture (DAC). The potential degradation pathway of imidazolium cyanopyrrolide, an ionic liquid (IL) functionalized for superior CO 2 capacity and selectivity, is evaluated under accelerated degradation conditions to elucidate the secondary reactions that can occur during repetitive absorption‐desorption thermal‐swing cycles. The combined analysis from various spectroscopic, chromatographic, and thermal gravimetric measurements indicated that radical and S N 2 mechanisms in degradation are encouraged by the nucleophilicity of the anion. Thickening of the liquid and gas evolution are accompanied by 50 % reduction in CO 2 capacity after a 7‐day exposure to O 2 under 80 °C. To prevent long exposure to conventional thermal heating, microwave (MW) regeneration of the CO 2 ‐reactive IL is used, where dielectric heating at 80 and 100 °C rapidly desorbs CO 2 and regenerates the IL without any measurable degradation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Charge Transport in Imidazolium-Based Homo- and Triblock Poly(ionic liquid)s

Ion dynamics in a series of imidazolium-based triblock copolymers (triblock co-PILs) are investigated using broadband dielectric spectroscopy (BDS) and differential scanning calorimetry (DSC) and compared to their homopolymer counterparts (homo-PILs). Two calorimetric glass transition temperatures (T g ) are observed corresponding to the charged poly(ionic liquid) (PIL) blocks and noncharged polystyrene (PS) blocks. Varying the counterion from Br – to NTf 2 – decreases the T g of the charged block by over 50 °C, thereby increasing the room-temperature ionic dc conductivity by over 6 orders of magnitude. Interestingly, for a given anion, varying the volume fraction of the charged block, from ~0.5 to ~0.8, has very minimal effect on the dc ionic conductivity, indicating that the choice of counterion is the key factor influencing charge transport in these systems.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Organometallic Synthesis of Bimetallic Cobalt‐Rhodium Nanoparticles in Supported Ionic Liquid Phases (Co x Rh 100− x @SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates

Abstract The synthesis, characterization, and catalytic properties of bimetallic cobalt‐rhodium nanoparticles of defined Co:Rh ratios immobilized in an imidazolium‐based supported ionic liquid phase (Co x Rh 100− x @SILP) are described. Following an organometallic approach, precise control of the Co:Rh ratios is accomplished. Electron microscopy and X‐ray absorption spectroscopy confirm the formation of small, well‐dispersed, and homogeneously alloyed zero‐valent bimetallic nanoparticles in all investigated materials. Benzylideneacetone and various bicyclic heteroaromatics are used as chemical probes to investigate the hydrogenation performances of the Co x Rh 100− x @SILP materials. The Co:Rh ratio of the nanoparticles is found to have a critical influence on observed activity and selectivity, with clear synergistic effects arising from the combination of the noble metal and its 3d congener. In particular, the ability of Co x Rh 100− x @SILP catalysts to hydrogenate 6‐membered aromatic rings is found to experience a remarkable sharp switch in a narrow composition range between Co 25 Rh 75 (full ring hydrogenation) and Co 30 Rh 70 (no ring hydrogenation).

Rengshausen, Simon↗
DOE OSTI2016

Chemical and Radiation Stability of Ionic Liquids: A Computational Screening Study

Using a variety of density functional theory (DFT) methods, we present a systematic computational screening effort to analyze the chemical and radiation stability for a large number of anions and cations that constitute room-temperature ionic liquids (RTILs). We compute various electronic properties such as the HOMO–LUMO gap, the ionization potential, and the electron affinities for a large library of ions (42 cations and 42 anions). The theoretical analysis provides the most comprehensive characterization of the chemical and radiation stability of individual ions in RTILs to date. Our calculations reveal that cation stability is closely related to constituent alkyl chain length and branching, whereas the anion stability is mostly dictated by ion size and electronegativity. Furthermore, these calculations show that the ωB97XD functional is the most internally consistent for predicting the chemical and radiation stability. In conclusion, these calculations establish a chemical stability database and a theoretical procedure for further experimental and computational studies of RTILs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Improved Lubricating Performance by Combining Oil-Soluble Hairy Silica Nanoparticles and an Ionic Liquid as an Additive for a Synthetic Base Oil

This article reports on improved lubricating performance by combining oil-soluble poly(lauryl methacrylate) brush-grafted silica nanoparticles (hairy NPs or HNP) and an oil-miscible phosphonium-phosphate ionic liquid (IL) as a friction-reducing additive for a polyalphaolefin (PAO) oil. The HNP was synthesized by surface-initiated reversible addition–fragmentation chain transfer polymerization. At a total concentration of 2% and sufficiently high individual concentrations for HNP and IL in PAO, high-contact stress, ball-on-flat reciprocating tribological tests showed that the friction decreased by up to 23% compared with 2% HNP alone in PAO and by up to 35% compared to the PAO mixed with 2% IL. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy (XPS) analysis revealed that the tribofilm formed from the PAO containing 1% HNP + 1% IL was enriched with both Si and P, indicating that both hairy NPs and IL were involved in the tribochemical reactions. In addition, the O 1s and Si 2p peaks in the core-level XPS spectra exhibited significant shifts for the mixture of 1% HNP + 1% IL compared to those for 2% HNP, suggesting the possible formation of new covalent bonds. These results indicated that HNP and IL reacted with each other and also with the metal substrate during the rubbing process, which likely strengthened the tribofilm and its bonding with the substrate and thus further improved the lubrication.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electrostatic Interactions Control the Nanostructure of Conjugated Polyelectrolyte–Polymeric Ionic Liquid Blends

Polyelectrolyte complexation offers unique opportunities to compatibilize polymers with very different backbone chemistries and to control the morphology of the resulting blend via electrostatic manipulation. In this study, we demonstrate the ability to formulate homogeneous complexes of a conjugated polyelectrolyte with a polymeric ionic liquid, utilizing the electrostatic attraction among their oppositely charged side chains. Variation of electrostatic parameters, such as counterion concentration or polymer charge fraction, tunes the morphology of these polymer complexes from homogeneously disordered blend to weakly structured microemulsion where the local ordering arises from backbone-immiscibility-induced microphase segregation. Our experimental observations are in qualitative agreement with both field-theoretic simulation and random-phase approximation calculations. Simulated morphology snapshots suggest and experimental evidence also indicates that the microphase-segregated complex likely takes on a cocontinuous microemulsion structure. Our findings show that ionic interactions are an effective pathway to compatibilize polymers at macroscopic length scales while achieving controlled nanostructures in these ionic blends. Such systems have great potential for engineering the nanostructure of polymers to tailor applications such as nanofiltration, catalysis, and energy storage, where local ordering can enhance the physical properties of an otherwise macroscopically homogeneous structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Physical insight into switchgrass dissolution in the ionic liquid 1-ethyl-3-methylimidazolium acetate

Small-angle neutron scattering was used to characterize solutions of switchgrass and the constituent biopolymers cellulose, hemicellulose, and lignin, as well as a physical mixture of them mimicking the composition of switchgrass, dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate. The results demonstrate that the IL dissolves the cellulose fibrils of switchgrass, although a supramolecular biopolymer network remains that is not present in solutions of the individual biopolymers and that does not self-assemble in a solution containing the physical mixture of the individual biopolymers. The persistence of a network-like structure indicates that dissolving switchgrass in the IL does not disrupt all of the physical entanglements and covalent linkages between the biopolymers created during plant growth. Reconstitution of the IL-dissolved switchgrass yields carbohydrate-rich material containing cellulose with a low degree of crystallinity, as determined by powder X-ray diffraction, which impacts potential down-stream uses of the biopolymers produced by the process. The data suggests that the use of chemical additives which would break bonds that exist between the lignin and hemicellulose might improve the purity of the resulting product, but may not be able to disrupt the highly physically-entangled biopolymer network sufficiently to facilitate their separation.

Wang, Hui↗
DOE OSTI2019

110th Anniversary: High-Molecular-Weight Chitin and Cellulose Hydrogels from Biomass in Ionic Liquids without Chemical Crosslinking

In this work, cellulose, chitin, and composite 3D hydrogels and membranes were fabricated without any chemical modification from high-molecular-weight chitin and cellulose-rich material (CRM) extracted from shrimp shell or pine wood, respectively, using the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]). The hydrogels were prepared by redissolution of the extracted biopolymers in the same IL, or in a one-pot process directly from a solution of the biomass after extraction, followed by molding/gelation (“3D gels”) or casting (membranes), and then washing. For comparison, the preparation of gels was attempted using commercial microcrystalline cellulose or chitin. From all of the sources, the regenerated CRM or chitin required significantly lower load. Hydrogels were also converted to aerogels via transformation to alcogels and then Sc-CO 2 drying, giving materials of low density, high porosity, favorable compressibility, high water uptake, and moderate antioxidant activity. Air-dried membranes were dense, of high tensile strength, and exhibited high water-vapor transmission.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium

Abstract Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium acetate ([C 2 mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C 2 mim] n [{Ln 2 (OAc) 7 } n ] and the dimeric [C 2 mim] 2 [Ln 2 (OAc) 8 ], based on the ion size and the ratio of IL used. A reaction with an IL : Ln‐salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy−Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal‐acetate coordination modes where η 2 μκ 2 is the most represented in both structure types.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Sulfur tolerant hydrophobic ionic liquid solvent

Exemplary embodiments relate to methods for removal of CO.sub.2 and other acid gases from gaseous fuels prior to combustion. Exemplary methods may be used for CO.sub.2 capture, H.sub.2 purification and natural gas sweetening. Exemplary methods use at least one ionic liquid that has excellent CO.sub.2 solubility, selectivity over hydrogen, low viscosity, and resistance to H.sub.2S.

03 NATURAL GAS↗
DOE OSTI2025

Ionic‐Liquid Free and Flexible Transistors Made of 2D Material Inks

The development of thin-film transistors (TFTs) using 2D materials is crucial for enabling scalable, low-cost, and flexible electronics. Currently, 2D TFTs with the highest performance have been achieved by using ionic-liquid gating (ILG), a technique suited for proof-of-concept studies. However, ILG suffers from slow switching speeds, temperature sensitivity, poor long-term stability, and integration challenges, making it unsuitable for practical use. Moreover, typical fabrication methods for 2D TFTs involve harsh conditions such as strong acids or high temperatures (>300 °C), limiting integration with flexible substrates. This work provides the first demonstration of an ILG-free, all-2D-material TFT fabricated onto a flexible substrate. Water-based graphene and hexagonal boron nitride (h-BN) inks are printed to deposit the electrodes and dielectric layers, respectively. The MoS 2 channel is produced via supramolecular interfacial self-assembly, yielding uniform, monolayer-rich films transferable to rigid and flexible substrates. The resulting TFTs operate below 3 V, exhibit negligible leakage current, and achieve field-effect mobilities up to 0.46 cm 2 V −1 s −1 (rising to 2.47 cm 2 V −1 s −1 with silver electrodes) measured under ambient conditions, while maintaining excellent mechanical flexibility. This work establishes a low-cost and scalable solution-processable platform for flexible electronics based on 2D materials that match requirements for practical applications.

2D materials↗
DOE OSTI2021

Prediction of solubility parameters of lignin and ionic liquids using multi-resolution simulation approaches

The solubility parameter (SP) of a molecular species is a vital feature that indicates polarity and quantifies the ‘like-seeks-like’ principle, which is used in chemistry to screen solvents for dissolution. Recent studies have demonstrated that ionic liquids (ILs) and deep eutectic solvents (DESs) efficiently solubilize lignocellulosic biomass and promote enzymatic saccharification into sugars used for the production of biofuels and value-added chemicals. Understanding the solubility of plant biopolymers, particularly lignin, in ILs and DESs is critical for selecting candidate ILs and DESs for biomass pretreatment; however, experimentally measuring SPs is challenging. Thus, the present study investigates lignin dissolution mechanisms in IL/DES and prediction of the solubility parameters (Hildebrand and Hansen) of lignin, ILs, and DESs using multi-resolution simulation approaches. Here, solubility parameters of the studied compounds were predicted using molecular dynamics (MD) simulations, and the SP of lignin was determined to be 23–27 MPa 1/2 , which was close to the polymeric lignin solubility parameter (24.3–25.5 MPa 1/2 ). The SPs of ILs namely [Ch][Lys], [Ch][Oct], and [Emim][Lys] were predicted to be ~26 MPa 1/2 , which is close to lignin's SPs and resulted in increased biomass delignification. The MD simulated SPs were validated by both the COSMO-RS model and experimental investigations, with the results showing a close agreement between the predicted and experimentally obtained SPs. In addition, the enthalpy of vaporization (ΔH vap ) of ILs/DESs was predicted based on the potential energy of the system, and the ΔH vap of ILs/DESs was around 40–65 kcal mol –1 , which is 5–8 times higher than that of traditional organic solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Improved Stability of Oxysulfide Solid-State Electrolytes in Li(G3)TFSI Solvate Ionic Liquid Electrolyte

The performance of all solid-state batteries is limited by poor interfacial contact between active material and solid-state electrolyte (SSE) particles. Semi-solid batteries utilize a secondary electrolyte phase to wet the SSE/AM interface to improve cell performance. Solvate ionic liquids (SILs) are one class of liquid electrolytes under consideration for use in semi-solid batteries. This paper focuses on the Li(G3)TFSI SIL consisting of the bis(trifluoromethanesulfonyl)imide (TFSI − ) anion coupled to a [Li(G3)] + solvate cation. Sulfide SSEs are normally subject to nucleophilic attack by trigylme (G3), however, strong coordination of Li + to G3 in the [Li(G3)] + solvate cation prevents this reaction from taking place. Consequently, the stability of sulfide SSE depends on the ideal 1:1 molar ratio of G3 to TFSI, which may be difficult to maintain. We studied the chemical stability of 70Li 2 S·(30-x)P 2 S 5 ·xP 2 O 5 (x = 0, 2, 5, 10) (oxy)sulfide solid-state electrolyte in Li(G3)TFSI SIL. By physical measurement, UV–vis spectroscopy, electrochemical evaluation, X-ray photoelectron spectroscopy, and first principles calculation it is shown that increased oxygen content improves the stability of SSE in various Li(G3) x TFSI (x = 1, 2, 3, 4) liquid electrolytes. The results suggest that an oxysulfide SSE + SIL semi-solid electrolyte is a good choice for future semi-solid battery designs.

Electrochemistry↗
DOE OSTI2014

Comparison of enzymatic reactivity of corn stover solids prepared by dilute acid, AFEX™, and ionic liquid pretreatments

Background: Pretreatment is essential to realize high product yields from biological conversion of naturally recalcitrant cellulosic biomass, with thermochemical pretreatments often favored for cost and performance. In this study, enzymatic digestion of solids from dilute sulfuric acid (DA), ammonia fiber expansion (AFEX™), and ionic liquid (IL) thermochemical pretreatments of corn stover were followed over time for the same range of total enzyme protein loadings to provide comparative data on glucose and xylose yields of monomers and oligomers from the pretreated solids. The composition of pretreated solids and enzyme adsorption on each substrate were also measured to determine. The extent glucose release could be related to these features. Results: Corn stover solids from pretreatment by DA, AFEX, and IL were enzymatically digested over a range of low to moderate loadings of commercial cellulase, xylanase, and pectinase enzyme mixtures, the proportions of which had been previously optimized for each pretreatment. Avicel® cellulose, regenerated amorphous cellulose (RAC), and beechwood xylan were also subjected to enzymatic hydrolysis as controls. Yields of glucose and xylose and their oligomers were followed for times up to 120 hours, and enzyme adsorption was measured. IL pretreated corn stover displayed the highest initial glucose yields at all enzyme loadings and the highest final yield for a low enzyme loading of 3 mg protein/g glucan in the raw material. However, increasing the enzyme loading to 12 mg/g glucan or more resulted in DA pretreated corn stover attaining the highest longer-term glucose yields. Hydrolyzate from AFEX pretreated corn stover had the highest proportion of xylooligomers, while IL produced the most glucooligomers. However, the amounts of both oligomers dropped with increasing enzyme loadings and hydrolysis times. IL pretreated corn stover had the highest enzyme adsorption capacity. Conclusions: Initial hydrolysis yields were highest for substrates with greater lignin removal, a greater degree of change in cellulose crystallinity, and high enzyme accessibility. Final glucose yields could not be clearly related to concentrations of xylooligomers released from xylan during hydrolysis. Overall, none of these factors could completely account for differences in enzymatic digestion performance of solids produced by AFEX, DA, and IL pretreatments.

09 BIOMASS FUELS↗
DOE OSTI2015

Genome Sequence of Halomonas sp. Strain KO116, an Ionic Liquid- Tolerant Marine Bacterium Isolated from a Lignin-Enriched Seawater Microcosm

Halomonas sp. strain KO116 was isolated from Nile Delta Mediterranean Sea surface water enriched with insoluble organosolv lignin. It was further screened for growth on alkali lignin minimal salts medium agar. The strain tolerates the ionic liquid 1-ethyl-3-methylimidazolium acetate. Its complete genome sequence is presented in this report.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Hybrid Membrane-based Ionic Liquid Absorption Cycle for Water Heating, Dehumidification, and Cooling

To meet the growing energy consumption and mitigate climate concerns, novel energy efficient technologies need to be developed. Water heating, dehumidification and space cooling form a significant percentage (~24%) of a typical U.S. household energy consumption and a total of 2.6 quad of primary energy consumption. In this paper, we present a novel system for combined water heating, dehumidification, and space cooling. The three processes can be achieved by one device using a novel semi-open absorption based system combined with evaporative cooling. The absorption based system absorbs water vapor from its ambient. The latent heat of absorption, released into the absorbent, is transferred into the process water that cools the absorbent. The water absorbed is later released in the desorber through heating, and the water vapor generated in the desorber is condensed and its heat of phase change is transferred to the process water in the condenser. The condensed water vapor can either be drained if dehumidification is desired or be used in an evaporative cooling process for space cooling. The major innovations that enable such an absorption-based device are demonstrated in this study through an experimental test setup. First, a membrane based absorption system in a compact and scalable platform is used to alleviate the liquid entrainment issue encountered in the conventional packed bed absorbers. Second, architecture reconfigurations, like novel fluid circuits and semi-open absorption system are deployed to enhance performance and lower system cost. Finally, an ionic liquid is implemented to minimize corrosion and eliminate crystallization risks, a major concern with conventional salts. The water heating and dehumidification component of the device are experimentally evaluated and the device is characterized for various system parameters. A water heating COP of 1.4 is achieved in this first generation prototype. These innovations pave the way for a compact, efficient, and low cost absorption based system for residential scale applications.

CHUGH, Devesh↗
DOE OSTI2018

Temperature Dependence of Volumetric and Dynamic Properties of Imidazolium-Based Ionic Liquids

Atomistically detailed molecular dynamics simulations were used to investigate the temperature dependence of the specific volume, dynamic properties, and viscosity of linear alkyl chain ([C n C 1 Im][NTf 2 ], n = 3–7) and branched alkyl chain ([(n – 2)mC n–1 C 1 Im][NTf 2 ]) ionic liquids (ILs). The trend of the glass transition temperature (T g ) values obtained in the simulations as a function of the alkyl chain length of cations was similar to the trend seen in experiments. In addition, the system relaxation behavior as determined from the temperature dependence of the diffusion coefficient, rotational relaxation time, and viscosity close to T g was observed to follow the Vogel–Fulcher–Tammann expression. Furthermore, the reciprocal of the diffusion coefficient of the anion and cation in both linear and branched IL systems showed a linear correlation with viscosity, thus confirming the validity of the Stokes–Einstein relationship for these systems. Similarly, the average rotational relaxation time of the ions was also found to correlate linearly with the viscosity of the ILs over a wide range of temperatures, thereby validating the Debye–Stokes–Einstein relationship for the ILs. These simulation findings suggest that the temperature dependence of the relaxation time of ILs is very similar to that of other glass-forming liquids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗