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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Pulping of Crustacean Waste Using Ionic Liquids: To Extract or Not To Extract

We present that ionic liquids (ILs), such as hydroxyammonium acetate ([NH 3 OH][OAc]), can reactively demineralize and remove proteins from shrimp shells in an efficient one-pot pulping process, thus allowing the isolation of native chitin with >80% purity and a high degree of acetylation and crystallinity. Compared to a previously reported IL extraction using 1-ethyl-3 methylimidazolium acetate, [C 2 mim][OAc], these less expensive ILs can achieve comparable chitin yields and purity, at up to ten times the biomass loading, although potentially result in lower molecular weight (MW) chitin. Because the IL is not recovered or recycled, the cost can additionally be further reduced by the sequential addition of hydroxylamine and acetic acid (or vice versa) to conduct the pulping process in situ. Though each methodology results in a comparable yields and purity of chitin material, the varying production costs and process safety issues are still unknown. Finally, this work presents a step toward narrowing the choices for chitin isolation technologies that can lead to an economically and environmentally sustainable process replacing the current hazardous, energy consuming, and environmentally unsafe process.

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

Ionic Liquid Platform for Spinning Composite Chitin–Poly(lactic acid) Fibers

In the design of stronger chitin fibers reinforced with poly(lactic acid) (PLA), during this work, an ionic-liquid-based (IL-based) approach was developed in which both polymers were codissolved in an 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]) and wet-jet spun into composite fibers. Chitin, directly extracted from shrimp shell, had a solubility in the IL of 2.75 wt %, while PLA of MW 700 000 g/mol had a solubility of 49 wt %. Keeping the IL saturated in chitin, homogeneous solutions of chitin and PLA could be obtained up to 27 wt % (relative to the IL) PLA. Spinning dopes were prepared by maintaining the chitin concentration relative to the IL at 1.75 wt % and adding PLA in chitin to PLA weight ratios of 1:0.1 through 1:1 (PLA concentrations of 0.175–1.75 wt % relative to the IL). Homogeneous chitin/PLA fibers could be spun when the chitin to PLA ratio was between 1:0.1 and 1:0.3. The tensile strength and plasticity of the fibers depended on the chitin to PLA ratio with the highest plasticity (8.8% vs 3.0% for pure chitin fibers), strength (112 vs 71 MPa), and stiffness (5.9 vs 4.2 GPa) observed for fibers with a chitin to PLA ratio of 1:0.3. Studies of the fracturing surface of the fibers indicated that fracturing occurred through an initial disruption of the interactions between polymer chains, followed by complete fiber breakage. The work not only demonstrates that homogeneous composite fibers can be spun using a biopolymer and PLA additive, but also suggests a versatile platform for preparation of multiple biopolymer–PLA materials using solution processing methods.

1-Ethyl-3-methylimidazolium acetate↗
DOE OSTI2017

Targeted Metabolomics of the Phenylpropanoid Pathway in Arabidopsis thaliana using Reversed Phase Liquid Chromatography Coupled with Tandem Mass Spectrometry: Measuring Lignin Precursors by LC-MS

The phenylpropanoid pathway is a source of a diverse group of compounds derived from phenylalanine, many of which are involved in lignin biosynthesis and serve as precursors for the production of valuable compounds, such as coumarins, flavonoids, and lignans. Consequently, recent efforts have been invested in mechanistically understanding monolignol biosynthesis, making the quantification of these metabolites vital. To develop an improved and comprehensive analytical method for (i) extensively profiling, and (ii) accurately quantifiying intermediates of the monolignol biosynthetic network, using Arabidopsis thaliana as a model system. A liquid chromatography-tandem mass spectrometry with electrospray ionization was developed to quantify phenylpropanoid metabolites in Arabidopsis wildtype and cinnamoyl CoA reductase1 (CCR1) deficient lines (ccr1). Vortexing at high temperatures (65°C) enhanced release of phenylpropanoids, specifically the more hydrophobic compounds. A pH of 5.3 and ammonium acetate buffer concentration of 2.5 mM resulted in an optimal analyte response across standards. Ion suppression was estimated using standard spike recovery studies for accurate quantitation. The optimized method was used to profile Arabidopsis wildtype and ccr1 stems. An increase in hydroxycinnamic acid derivatives and a decrease in the hydroxycinnamyl aldehydes and alcohols in ccr1 lines, supports a shift of flux from lignin synthesis to other secondary metabolites and phenylpropanoid derivatives. Compared to existing targeted profiling techniques, our method is capable of quantifying a wider range of intermediates (15 out of 22 in WT Arabidopsis stems) at low in vivo concentrations (~50 pmol/g-FW for certain compounds), while requiring minimal sample preparation.

09 BIOMASS FUELS↗
DOE OSTI2024

Evaluation of liquid metal embrittlement of F82H and 4340 steels in liquid lithium

Here, to evaluate the liquid metal embrittlement (LME) susceptibility of F82H, a reduced activation ferritic-martensitic (RAFM) steel, a testing procedure using hollow cylindrical tensile specimens was used. Tensile tests are compared between specimens filled with argon and lithium at 200 °C. To validate the procedure, initial testing was performed on type 4340 steel, which is well-known to exhibit LME. Compared to 4340 steel, F82H only showed minor effects of Li exposure, including pre-testing exposures with Li at 400 °C for 1 h and 500 °C for 500 h. Furthermore, changing the strain rate or tensile test temperature also did not show significant embrittlement.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Liquid and liquid–gas flows at all speeds

All speed flows and in particular low Mach number flow algorithms are addressed for the numerical approximation of the Kapila et al. [1] multiphase flow model. This model is valid for fluid mixtures evolving in mechanical equilibrium but out of temperature equilibrium and is efficient for material interfaces computation separating miscible and non-miscible fluids. In this context, the interface is considered as a numerically diffused zone, captured as well as all present waves (shocks, expansion waves). The same flow model can be used to solve cavitating and boiling flows [2]. Many applications occurring with liquid–gas interfaces and cavitating flows involve a very wide range of Mach number, from 10{sup −3} to supersonic (and even hypersonic) conditions with respect to the mixture sound speed. It is thus important to address numerical methods free of restrictions regarding the Mach number. To do this, a preconditioned Riemann solver is built and embedded into the Godunov explicit scheme. It is shown that this method converges to exact solutions but needs too small time steps to be efficient. An implicit version is then derived, first in one dimension and second in the frame of 2D unstructured meshes. Two-phase flow preconditioning is then addressed in the frame of the Saurel et al. [3] algorithm. Modifications of the preconditioned Riemann solver are needed and detailed. Convergence of both single phase and two-phase numerical solutions are demonstrated with the help of single phase and two-phase steady nozzle flow solutions. Last, the method is illustrated by the computation of real cavitating flows in Venturi nozzles. Vapour pocket size and instability frequencies are reproduced by the model and method without using any adjustable parameter.

42 ENGINEERING↗
DOE OSTI2019

Is more always better? Tribofilm evolution and tribological behavior impacted by the concentration of ZDDP, ionic liquid, and ZDDP-Ionic liquid combination

Anti-wear additives (AWs), like zinc dialkyldithiophosphates (ZDDPs), have been used in lubricants for more than a half-century, and more effective candidate AWs, like oil-soluble ionic liquids (ILs), are emerging. However, there is a lack of fundamental understanding of how the AW concentration impacts the tribochemical activities at the contact interface. This study systematically investigated the friction and wear behavior in correlation to the tribofilm morphology and composition as a function of the concentration of a ZDDP, a phosphonium-alkylphosphate IL, and an IL+ZDDP combination. The ZDDP concentration rising from 0.4 to 6.4 wt% caused a proportionally increased friction coefficient, which was well correlated to a thicker, rougher, and more brittle tribofilm. This was further understood by the decreasing phosphates but increasing sulfur compounds in the ZDDP tribofilm. In contrast, the IL and IL+ZDDP maintained a low and stable friction coefficient at 0.5 wt% or above. There was no sulfur in the IL tribofilm, and the sulfur compounds were maintained at a low level in the tribofilm for IL+ZDDP even at high concentrations. Results suggested minimizing the sulfur content in the tribofilm would be an effective way to control the friction. An interesting V-shape relationship between the AW concentration and the wear loss was observed for both the IL-containing AWs, with an optimum at 2 wt% for the IL alone and 0.46–0.92 wt% for the IL+ZDDP, respectively. A unique heat map was created using the phosphorus binding energy distribution to reveal the phosphate polymerization at different depths of the tribofilms, which provided additional insight for the tribofilm evolution.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Analysis of the Frequency and Diversity of 1,3-Dialkylimidazolium Ionic Liquids Appearing in the Literature

The hypothetical assertion that there are potentially millions of ionic liquids (ILs) can be validated using basic knowledge of IL precursors and simple calculations. While it is an interesting thought exercise to ponder the possibilities of ILs, it is important to investigate how many discrete ILs (i.e., unique cation and anion pairings) have actually been synthesized and reported in the literature. A complete analysis of all ILs is a daunting task, especially if the definition of what constitutes an IL is broad. Nonetheless, insight can be gained into the use of ILs over the past ~20 years from a focused analysis of systematically varied 1,3-dialkylimidazolium-based ILs (i.e., [R 1 R 2 im][X], where R 1 and R 2 are n-alkyl chains and X is either a halide or molecular anion). This family of ILs includes many of the most widely used and most thoroughly studied IL substances, including 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4 mim][PF 6 ]) and 1-ethyl-3-methylimidazolium bistriflimide ([C 2 mim][Tf 2 N]). Using data retrieved from SciFinder searches, we analyzed the variety and frequency of 1,3-dialkylimidazolium-based ILs appearing in the literature. Our analysis reveals that there is a relatively large number of simple 1,3-dialkylimidazolium cations which have not yet been synthesized. Our findings indicate that despite the broad possibilities of IL structures available, there are but a handful of ILs that are commonly used and studied. Within the 1248 [R 1 R 2 im][X] ILs studied, there were only 12 cations extensively used, which included [R 1 R 2 im] + (R 1 = C 1 and R 2 = C 1 –C 12 ). Of the 16 anions studied, only 5, including [BF 4 ] – , [Cl] – , [PF 6 ] – , [Tf 2 N] – , and [Br] – , were used significantly. Thus, it appears that although ILs can be used as designer solvents with task-specific properties, there is a small default subset of ILs, which are “go-to” or “one-size-fits-all.” Here, we rationalize the current state of the IL landscape in terms of the historical perceptions (and misconceptions) around ILs, familiarity, availability and cost of starting materials, commercial availability of ILs, and the motivations from which researchers choose to synthesize and characterize new ILs.

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

Imidazole and 1-Methylimidazole Hydrogen Bonding and Nonhydrogen Bonding Liquid Dynamics: Ultrafast IR Experiments

Dynamics of imidazole (IM) and 1-methylimidazole (1-MeIM) in the liquid phase at 95 °C were studied by IR polarization selective pump-probe (PSPP) and two-dimensional IR (2D IR) spectroscopies. The two molecules are very similar structurally except that IM can be simultaneously a hydrogen bond donor and acceptor and therefore forms extended hydrogen bonded networks. The broader IR absorption spectrum and shorter vibrational lifetime of the vibrational probe, selenocyanate anion (SeCN – ), in IM vs. 1-MeIM indicate that stronger hydrogen bonding exists between SeCN – and IM. Molecular dynamics (MD) simulations support the strong hydrogen bond formation between SeCN – and IM via the HN moiety. SeCN – makes two H-bonds with IM; it is inserted in the IM H-bonded chains rather than being a chain terminator. The strong hydrogen bonding influenced the reorientation dynamics of SeCN – in IM, leading to more restricted short time angular sampling (wobbling-in-a-cone). The complete orientational diffusion time in IM is 1.7 times slower than in 1-MeIM, but the slowdown is less than expected, considering the 3-fold larger viscosity of IM. The jump reorientation mechanism accounts for the anomalously fast orientational relaxation in IM, and the MD simulations determined the average jump angle of the probe between hydrogen bonding sites. Spectral diffusion time constants obtained from the 2D IR experiments are only modestly slower in IM than in 1-MeIM in spite of the significant increase in viscosity. Here, the results indicate that the spectral diffusion sensed by the SeCN – has IM hydrogen bond dynamics contributions not present in 1-MeIM.

14 SOLAR ENERGY↗
DOE OSTI2021

How Do Ionic Liquids “Fold” Ionenes? Computational and Experimental Analysis of Imidazolium Polymers Based on Ether and Alkyl Chain Variations Dissolved in an Ionic Liquid

Molecular dynamics (MD) simulations and complementary experiments are used here to understand the inter- and intramolecular structure and conformational properties of ionenes (i.e., cationic polymers formed from condensation reactions) dissolved in an ionic liquid (IL), 1-ethyl-3-methylimidazolium bistriflimide [C 2 mim + ][Tf 2 N - ]. The simulated structural properties are benchmarked against experimental analyses of these same polymers, mainly using dynamic light scattering (DLS) experiments. Four different imidazolium ionenes are considered, corresponding to variations in the chemistry and structure of the repeat units including: (1) poly (decylimidazolium) (PD 10 ); (2) poly (tetraethyleneglycolimidazolium) (PE 10 ); (3) alternating copolymer (P(ED) 5 ); and (4) a block copolymer (PE 5 D 5 ). Detailed computational analyses of the polymer structure and conformational properties were performed, including the radius of gyration, end-to-end distance, torsional distributions, and site-site and spatial distribution functions. Overall, there is a competition between intramolecular associations between the imidazolium groups and the ether sites in the polymers versus the intermolecular interactions of the polymer imidazolium groups with the surrounding anion molecules. The polymer with only ether linkages (PE 10 ) results in the most intramolecular interactions, leading to significant coiling behavior and chain contraction. These strong interactions reduce chain flexibility, but they also result in much more linear chain configurations and alignment of the imidazolium groups. The polymer structure is strongly affected as the concentration of alkyl groups is increased, and we find that the polymer architecture (alternating versus block copolymer) also has an important influence. Furthermore, these detailed observations are important for understanding the connection between the molecular design of imidazolium polymers and their emergent structural properties, which could lead to unique opportunities for creating polymer composites.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Liquid–Solid Mixtures of Ga Metal Infused with Cu Microparticles and Nanoparticles for Microscale and Nanoscale Patterning of Solid Metals at Room Temperature

This paper demonstrates and characterizes a simple ink for nanopatterning of solid metallic structures under ambient conditions by taking advantage of the low melting point of gallium and its affinity to form intermetallics with other metals. Bare copper micro- and nanoparticles readily mix with liquid gallium near room temperature to form a paste that ultimately amalgamates into a dense solid when mixed at the appropriate concentration ratios. The paste has sufficient shelf life that can be extruded from a nozzle at modest temperatures to form solid three-dimensional (3D) shapes. Additionally, the paste can be molded at room temperature to replicate feature sizes ranging from a few millimeters down to hundreds of nanometers. In situ X-ray diffraction (XRD) and thermo-mechanical analysis (TMA) data show gallium and copper readily interdiffuse to form the thermodynamically expected intermetallic phase. We describe the capabilities and limitations of a simple way to pattern solid metals in an additive fashion (syringe-based extrusion) and with high resolution (molding) at or near room temperature. Here, the use of a paste that solidifies provides a novel route for 3D printing of solid metals at ambient temperatures as well as the creation of micro- and nanostructured metallic surfaces that may be useful for optics, non-wetting surfaces, or electronic microcomponents.

36 MATERIALS SCIENCE↗